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2bis/2014

Vo l u m e 3 0 . N u m be r 2bis . 2014

QUINTESSENZA INTERNAZIONALE & JOMI

Quintessenza Edizioni S.r.l. - Via Ciro Menotti 65 - 20017 Rho (MI) - Poste Italiane Spa - Sped. in A.P. D.L. 353/2003 (conv. in L. 27/02/04 n. 46) art. 1 comma 1, DCB - Milano

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I&J Quintessenza Internazionale

&JOMI

la rivista internazionale di implantologia chirurgia orale e maxillo-facciale Implant & Regenerative Therapy with Digital Dentistry Publication Supported by Zimmer Dental

E R O M R E O R F A T C N Y A T L I P L A M I U E Q H E T L B A D R O AFF

I am the Tapered SwissPlus® Dental Implant, I am designed to achieve excellent primary stability and my performance has been the subject of many studies1 based on 12 years of clinical experience. My all-in-one simplifies the different procedures. Smart and affordable, I have a multi-functional fixture mount managing most of clinical cases. Performance, simplicity and economy … I am Zimmer. Visit www.zimmerdental.com to learn more about SwissPlus Dental Implant. ©2013 Zimmer Dental Inc. All rights reserved for content and images. ZD1208, Rev. 6/13. 1. Rosenlicht JL. SwissPluss Implant System, part 1: surgical aspects and intersystem comparisons. Implant Dent. 2002;11:144-153.- Rosentlich JL. SwissPLus Implant System, part 2 : prostodontic aspects and intersystem comparisons. Implant Dent. 2002;11:249-257. - Gunaseelan R, Rajan M. Overwiew of the SwissPlus Implant System. J Oral Implantol. -2005;31:121-128. - Sunitha R, Ramakrishnan T, Kumar S, Emmadi P. Soft tissue preservation and crestal bone loss around single-tooth implants. J Oral Implantol. - 2008;34:223-229. - Ormanier Z, Palti A, Shifman A. Survival of immediately loaded dental implants in deficient alveolar bone sites augmented with ß-Tricalcium Phosphate. Implant Dent. 2006;15:395-402.

d e n I f e d e r y T I l I T a S Ver

I am building on the tradition of the tried-and-true Tapered Screw-Vent® Implant – with more than a decade of experience and over 2 million units sold, I offer a variety of crestal configurations for optimum flexibility and choice to conveniently meet your clinical needs. Leveraging the proprietary Platform Plus™ Technology to optimize your connection, and provide the highest torque values on the market — I strive for primary stability and immediate function. Versatility, clinical choice, quality, and innovation … I am Zimmer. Visit www.zimmerdental.com to learn more about the Tapered Screw-Vent Implant Family.

www.zimmerdental.com

©2012 Zimmer Dental Inc. All rights reserved. 6547, Rev. 8/12

www.zimmerdental.com

I wish you all a good read Prof. Mariano Sanz

VOLUME 30  •  NUMBER 2bis  •  2014

editorial

Dear Colleagues, I want to thank Quintessence, dr. Horst -Wolfgang Haase and Lauro Dusetti, for an invitation to make a welcome to the readers of this Special Edition of Quintessence International & JOMI. Implant & Regenerative Therapy with Digital Dentistry immediately gives the idea of the topics covered, their multidisciplinary nature, than are current and as such further investigation of which they need it. As always, the use of new medical devices or new therapies need to clinical pioneers with devoted skills have the ability to identify the most appropriate protocols, and then implement them, making them more predictable. I do not want to enter the single item, but the entire article collection confirms that the effort continues in the dental industry, through the development of products, and will allow us to give patients treatments more effective. From our side, we clinicians could have, increasingly, procedures that will allow us to obtain a more repeatable quality in the therapy itself.

ISSN 1723-7793

Publisher Quintessenza Edizioni Horst-Wolfgang Haase Director of Quintessenza Edizioni Lauro Dusetti Director in charge Cristina Reina Marketing & PR Office Lauro Dusetti (Management) Mob. 338 9312741 [email protected] Silvia Fassetti [email protected] Editor Barbara Rossi [email protected] Cristina Reina [email protected] Subscriptions Maria Calabrese [email protected] Marta Vergani [email protected] Administration Maria Calabrese [email protected] Congresses Lauro Dusetti [email protected] Silvia Fassetti [email protected] Marta Vergani [email protected]

Quintessenza Internazionale is an Italian-language quarterly, published by Quintessenza Edizioni s.r.l., Via Ciro Menotti 65 20017 Rho, Milan. Copyright © 2014 Literary ownership and all rights reserved to Quintessence Publishing Co. Inc. No part of the content of this publication may be reproduced or transferred in any form or on any electronic or mechanical support, photocopy, disk or piracy system without the express written authorisation of the Editor. The Editor declines all responsibility for manuscripts submitted without having been expressly requested by the publishers. The opinions published are those of the authors. Termination of subscriptions must be received by registered post, 3 months ahead of the expiry date. Quintessenza Edizioni is not responsible for missed deliveries of the publication due to reasons beyond its control.

Printing: Reggiani S.P.A. Via Dante Alighieri, 50 21010 Brezzo di Bedero (VA) - Italy Registered with the Court of Milan at no. 511 on 16-09-03 Registered for transmission by post: Decree law 353/2003 (converted into law no. 46 of 27/02/04) Art. 1(1) Commercial Business Division - Milan

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Scientific Director

Tiziano Testori Scientific Committee Lilia Bortolotti Antonio Carrassi Enrico Conserva Ugo Covani Massimo De Sanctis Fabio Galli Mauro Fradeani Luca Francetti Luigi Galasso

Enrico Gherlone Stefano Gracis Domenico Massironi Pierfrancesco Nocini Adriano Piattelli Giovan Paolo Pini Prato Giacomo Urbani Francesco Zuffetti Roberto Weinstein

Reading Committee Gianfranco Carnevale

Salvatore Longoni

Raffaele Cavalcanti

Massimiliano Martignoni

Matteo Chiapasco

Marco Morra

Ugo Consolo

Andrea Parenti

Gianpiero Cordioli

Stefano Parma Benfenati

Matteo Deflorian

Roberto Pontoriero

Sergio De Paoli

Loris Prosper

Danilo Di Stefano

Antonio Rocci

Giuseppe Ferronato

Eugenio Romeo

Luca Fumagalli

Massimo Simion

Giovanni Lodi

Giovanni Zucchelli

SUBSCRIPTIONS Subscriptions for 2013: Quintessenza Internazionale & JOMI + JOMI online – English version Full = print + online € 110.00 Online = online version only, € 70.00 Subscription rates include packaging and delivery costs. Form of payment By bank cheque or postal order, to: Quintessenza Edizioni s.r.l. Via Ciro Menotti 65 20017 - Rho, Milan Tel. 02.93.18.08.21

This publication is affiliated to the Italian Union of Periodicals (Unione Stampa Periodica Italiana)

VOLUME 30  •  NUMBER 2bis  •  2014

summary

Z immer 05

RevitaliZe Patient Solutions: preliminary results from a single cohort prospective study using Screw-Vent TSVT implants

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Lateral bone augmentation with a block allograft (Puros®, Zimmer dental) combined with GBR and followed by implant placement in a staged approach: A case report

23

Digital Dentistry meets Implantology The Munich Implant Concept - A case report

31

Surgical recommendations for allograft block grafting

41

Trabecular Metal™ Dental Implants: Overview of design and developmental research

51

Implant therapy with an innovative surface (trabecular metal™) and CAD/CAM restorations – a clinical case

A. Agnini, M. A Salama, A. Mastrorosa Agnini, H. Salama, C. FJ Stappert, D. Romeo

O. Argibay Lorenzo, C. Carral Freire, J. Blanco Carrión

F. Beuer, J. Schweiger, J. F. Güth

O. Blume, O. Richter, M. Back, T. Müller-Hotop

M. Collins, J. Bassett, H. Bo Wen, C. Gervais, M. Lomicka, S. Papanicolaou

K. Fischer, S. Fickl

57

Immediate post-extraction provizionalisation: aesthetic and functional stability after 13 years

63

Simultaneous TM implant placement and horizontal ridge augmentation with IngeniOs HA: A Case Report

69

High resolution histologic and histomorphometric analysis of block allografts in humans: Report of three cases

79

The ortho-perio-prosthodontic team-approach for successful management of the single-tooth implant in the esthetic zone

91

Preliminary outcome in consecutively treated case series with Trabecular Metal implants

97

Surgery All at Once™: Socket preservation and immediate placement of an implant in an infected site in the anterior region – a Case Report

B. Fissore

R. Gómez Meda

W. Gutwerk

G. Pellitteri, U. Schneider-Moser, L. Moser

C. M. Soardi, H-L Wang, E. Clozza, D. Zaffe, L. Checchi

W.P. van der Schoor, A.R.M. van der Schoor

VOLUME 30  •  NUMBER 2bis  •  2014

RevitaliZe Patient Solutions: preliminary results from a single cohort prospective study using Screw-Vent TSVT implants Alessandro Agnini*, Maurice A Salama**, Andrea Mastrorosa Agnini***, Henry Salama****, Christian FJ Stappert*****, Davide Romeo****** Purpose: The aim of this paper was to report preliminary results from a cohort of subjects treated with the RevitaliZe Patient Solutions approach. Clinical and radiographic results of axial and tilted implants up to fourteen months of loading are presented. Material and Methods: From September 2011 to May 2012, 7 patients were recruited and treated with a metal reinforced fixed full-arch prosthesis screw-retained over two axial and two tiled implants within 24 hours from the surgery. Final restorations were placed 6 months later. Follow-up visits were scheduled every 6 months and radiographic evaluation of peri-implant bone level changes was conducted. Results: Seven patients (5 females and 2 males) were followed up for an average of 11,88 months (range 8-16 months). Five subjects received implant treatment in both arches, resulting in 12 restorations. A total of 48 fixtures (Zimmer Screw-Vent TSVT) were placed and no failure was reported during the follow-up period, leading to 100% implant and prosthetic survival rates. Radiographic analysis after 6 months of loading was conducted for all prostheses. No significant difference in marginal bone loss was found between tilted and axial implants in both jaws. Conclusions: The present preliminary data suggests that immediate loading with RevitaliZe Patient Solutions could be considered a predictable and cost- and timeeffective approach for the treatment of total edentulism. Keywords: Dental implants, Fixed implant restoration, Immediate loading, Tilted implants.

* DDS, Private Practice Modena and Sassuolo - Assistant Professor Modena University. ** DMD, Private Practice Atlanta, GA. Asst Clinical Professor of Periodontology Medical College of Georgia, Augusta, GA - USA. *** DDS, Private Practice Modena and Sassuolo, Italy. **** DDM, Private Practice, Atlanta, GA, Asst. Clinical Professor of Periodontology, Medical College of Georgia, Augusta. ***** DDS, M.S., PhD, Professor and director of Implant Periodontal Prosthodontics, Department of Periodontics, University of Maryland schoolf of dentistry, Professor, department of Prosthodontics, Albert Ludwigs University, Freiburg, Germany. ****** DDS, PhD, Research Associate, department of Periodontics, University of Maryland School fo Dentistry, Baltimore, MD, Usa.

Correspondence: Andrea Mastrorosa Agnini Studio Agnini Odontoiatria Corso Canal Grande 3 - 41126 Modena, Italy E-mail: [email protected]

VOLUME 30  •  NUMBER 2bis  •  2014

INTRODUCTION According to the most recent review of the dental literature, immediate loading procedures for total edentulism have reported high percentages of clinical success1,2, therefore an increasing number of clinicians have adopted these protocols in their daily practice. The reduction of total treatment time and the possibility to deliver a functional implant prosthesis a few hours after the surgery represents notable advantages for patients, specially for individuals with a failing dentition because they can avoid the psychological trauma and discomfort of a transitional removable prosthesis3. An essential condition for immediate loading protocols is a minimum amount of fixtures primary stability, quantifiable in 35 Ncm4. Implant design, bone quality and quantity and a proper surgical technique strongly contribute to a fixed implant at the time of placement4-6 and the rigid splinting effect of provisional restoration directs the healing process towards osseointegration7,8.

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A g n i n i A, S a l a m a MA , M as t r o r o sa A g n i n i A , S a l a m a H , S ta p p e r t C FJ, R o m e o D

In the last years, different clinical studies assessed tilted implants as a feasible treatment option, bringing surgical and prosthetic advantages9. The rehabilitation of complete arches with only four implants (two anterior axial and two posterior tilted), supporting a fixed prosthesis with limited distal cantilever was analyzed in recent studies10,11. Encouraging clinical outcomes have been reported in the medium term12 and no difference in implant survival rate and marginal bone loss have been registered between axial and tilted fixtures13. The aim of this paper was to report preliminary results of RevitaliZe Patient Solutions, a new treatment modality that allows clinicians to immediately restore complete arches with a full-arch bridge screw-retained over two straight anterior and two posterior angled fixtures.

MATERIALS AND METHODS Study protocol The study was designed as a prospective singlecohort clinical trial conducted according to the principles of the Helsinki Declaration of 1975, as revised in 2000. Consecutively treated patients were included and scheduled to be followed for up to 10 years after loading. Subjects were explained all potential adverse effects and complications of treatment and they signed an informed consent to be included in the study. Surgical interventions and prosthetic phases were done in two clinical centers by one operator (AA) with experience in immediate loading rehabilitations.

Fig 1 57 year old patient presenting metal crowns from upper canine to contralateral and a partial removable denture to replace posterior teeth. Opposing dentition is composed by metallic crowns. Smile line can be considered average, exposing 10 teeth during maximum smile, while the incisal superior plane is distant from the inferior lip.

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Selection Criteria Patients were enrolled if they were older than 18 years as well as physically and psychologically able to undergo conventional implant surgery and restorative procedures (American Society of Anesthesiologist (ASA) class I or II)14. Further inclusion criteria were: edentulous arch or presence of teeth with unfavorable long-term prognosis; adequate bone volume in the anterior maxilla and anterior mandible for implant placement (10 mm height and 3.7 mm wide), based on the pre-operative CT scan measurements; patients who preferred fixed implant-supported rehabilitation without recurring to any bone grafting procedure. All implants had to reach a minimum insertion torque of 30 Ncm. If one or two implants failed to reach that level but the other fixtures have adequate primary stability, immediate loading was still performed. Main exclusion criteria were: presence of active infection or inflammation in the planned implant area; untreated periodontitis; serious problems of coagulation, disease of the immune system, uncontrolled diabetes and metabolic disease affecting bone; severe bruxism or clenching, heavy smoking (more than 25 cigarettes/day), radiation therapy to the head or neck region in the previous 5 years, alcoholism or use of drugs, pregnancy or lactation at the time of surgery, poor oral hygiene and motivation, and unavailability to attend regular follow-up visits.

Fig 2 Plaque and calculus were observed, as well as gingival recessions on some teeth in both arches. Mismatch in dental midlines is observed as well as disharmony in dental proportion.

VOLUME 30  •  NUMBER 2bis  •  2014

A g n i n i A , S a l a m a MA , M as t r o r o sa A g n i n i A , S a l a m a H , S ta p p e r t C FJ, R o m e o D

Pre-surgical assessment and treatment planning Arch size, bone volume, inter-arch relation and distance were evaluated pre-operatively by means of a clinical examination (Figure 1 and 2) and analysis of panoramic radiographs, periapical radiographs (Figure 3), computerized tomography scans, radiograph of the skull in lateral view and study models mounted in articulator. Before the surgery, a resin transfer plate was made duplicating the patient’s denture or based on a wax-up for partially edentulous patients, with a secure stop on the palate vault or on the retromolar triangle. Subsequently, an opening approximately at the level of the occlusal surface was made to use the plate as a surgical guide, as described by Biscaro15.

Surgical technique All surgical procedures were performed under intravenous sedation and local anesthesia (Figure 4). If some remaining teeth were present, they were extracted and their sockets were debrided with sterile saline solution. A mid-crestal incision was made, always excluding the retromolar triangle or the maxillary tuberosity, and a full thickness flap was reflected. Direct visualization of the mental nerve was made and the anterior loop was estimated with an atraumatic periodontal probe gently placed into the canal. Where necessary, regularization of the crest was performed with bony forceps and rotary instruments before stabilizing the resin transfer plate using the palatal vault or the retromolar area. Bone quality was evaluated based on Lekholm and Zarb classification16 and Tapered Screw-Vent implants (Zimmer Dental Inc., Carlsbad, California) were placed

Fig 3 Peri-apical x-rays show severe bone loss and a scenario of failing dentition, with horizontal resorption and vertical defects around natural teeth and maxillary implants. Pneumatization of maxillary sinuses prevents implants placement without recurring to sinus lift augmentations.

Fig 4 After two sessions of scaling and root planning necessary to reduce the marginal inflammation, some failing roots on the lower jaw were extracted, while the remaining pillars with a minimal stability were maintained to support a provisional acrylic bridge. A soft diet was suggested until the day of the surgery.

Fig 5  A 3.7 mm wide Tapered Screw-Vent implant (TSVT) is inserted with a 30 degreed inclination according to the protocol. Anterior straight fixture is already placed. Fig 6 Tooth extraction and immediate implant placement in the mandible. Post extraction gaps were filled with a mixture of autogenous bone and xenograft.

VOLUME 30  •  NUMBER 2bis  •  2014

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A g n i n i A, S a l a m a MA , M as t r o r o sa A g n i n i A , S a l a m a H , S ta p p e r t C FJ, R o m e o D

according to RevitaliZe Patient Solutions protocol (Figure 5 and 6). Tapered Screw-Vent abutments (Figure 7) and Spectra-Angle abutments (Zimmer Dental Inc., Carlsbad, California, USA) were screw retained to straight and tilted implants, respectively. Immediate provisional restoration Copings for open tray impression were positioned over the abutments and isolated with a sterile piece of rubber dam. Copings were connected to each other by orthodontic wire and acrylic resin (Pattern Resin, GC America) or composite Protemp 4 (3M ESPE, Pioltello, Milan, Italy) and then fixed to the surgical guide with the same material 17. After 5 minutes, the complex of impression copings and guide was removed, healing abutments were placed and flaps were sutured with Gore-Tex 5/0 (WL Gore & Associates, Flagstaff, Arizona, USA). Implant analogs were screwed on the impression copings and the stone was removed from the study

model in the area corresponding to implant placement. The entire complex made by surgical guide, impression copings and analogs were positioned again over the study model. New stone was placed to secure implant analogs, converting the study model in the final master cast 17 (Figure 8). A screw retained metal reinforced provisional was made (Figure 9 and 10) and positioned in the patient’s mouth the same day or within 24 hours after surgery (Figure 11). The immediate restoration contained no more than 12 teeth and distal cantilevers were usually avoided. Full occlusal contacts in centric occlusion were maintained for all teeth, while lateral interferences were removed. Final restoration protocol In absence of pain and inflammatory signs (Figure 12), the final restoration based on a CAD/CAM framework was delivered 6 months after loading. Five patients for a total of 10 arches were treated with a mono-

Fig 7  Spectra-Angle abutments were positioned over posterior implants to correct their inclination and get a favorable access for the prosthetic screw.

Fig 8 The complex made by surgical guide, impression copings and analogs rigidly connected with composite resin were positioned again over the study model to create the master model for the fabrication of the provisional bridge.

Fig 9 A metal framework is glued over 4 titanium cylinders to provide rigidity at the provisional prosthesis.

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Fig 10 Provisional restoration contains 12 teeth, with pink gingiva if necessary.

VOLUME 30  •  NUMBER 2bis  •  2014

A g n i n i A , S a l a m a MA , M as t r o r o sa A g n i n i A , S a l a m a H , S ta p p e r t C FJ, R o m e o D

lithic zirconium-oxide bridge, where just an external layer of 0.6 mm thickness from first premolar to the contralateral was modeled by dental technician to get a natural esthetic appearance (Figure 13-16). The morphology of the occlusal surfaces was entirely created from the monolithic block of zirconia. Two subjects were rehabilitated with titanium frameworks and veneering composite according to their desires.8

Fig 11  Immediate restorations are delivered within 24 hours from the surgery. Contacts in centric occlusion are maintain for all the 12 teeth while distal cantilevers, if present, are under the occlusal plane. Interferences in lateral excursion are removed.

Outcome Measures The main outcome measures for the present study were: 1. Prosthesis success: when the prosthesis was in function, without mobility or pain, even in face of the loss of one or more implants. Prosthesis stability was tested at each follow-up visit by means of two opposing instruments’ pressure.

Fig 12 After six months necessary for osseointegration, hard and soft tissues are stable for the final restorations.

Fig 13  Final bridge consists of a monolithic zirconiumoxided framework with a layer of 0.6 mm of veneering porcelain at the vestibular side of frontal teeth and first premolars. Fig 14 Frontal intra-oral view of final bridges.

Fig 15  A natural smile was obtained thanks to the materials used for the restorations and to the work of the dental technician.

VOLUME 30  •  NUMBER 2bis  •  2014

Fig 16 Final panoramic x-ray showing implant distribution and bone level around implants after 1 year of loading.

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A g n i n i A, S a l a m a MA , M as t r o r o sa A g n i n i A , S a l a m a H , S ta p p e r t C FJ, R o m e o D

Secondary outcomes were: 1. Implant survival: when the implant was in function and stable with no evidence of peri-implant radiolucency, no suppuration or pain at the implant site or ongoing pathologic processes18. 2. Biological and prosthetic complications, such as periimplantitis, fistula or abscess, mechanical or prosthetic complications like fracture of the implant or any prosthetic component19,20. 3. Plaque and Bleeding Indexes at implant level. Each implant was examined on four aspects (mesial, distal, vestibular, palatal/lingual). The percentage of sites in which plaque could be found, regardless of its amount, was recorded. A total of 16 sites per patient were examined, as previously described11. Briefly, any site in which plaque could be detected by naked eye or with a probe accounted for 6.25% (1/16) of the total score (100%). The same was made for bleeding index, considering positive any site that showed bleeding on probing11. 4. Patient satisfaction in term of aesthetics, phonetics and masticatory function was recorded by means of a questionnaire at baseline (before the treatment), at 7 months (after delivering the final prosthesis) and then at the 1-year and 2-year follow-ups21. The answers were based on a 5-point Likert-type scale, with scores ranging from “poor” to “excellent” (1 = poor, 2 = sufficient, 3 = good, 4 = very good, 5 = excellent). Data were statistically analyzed by means of the Fisher’s exact test. 5. Marginal bone level change: Periapical radiographs were performed using a long-cone paralleling technique and an individual x-ray holder at baseline, at 6 and 12 months, and yearly thereafter. Marginal bone level was assessed with an image analysis software (UTHSCSA Image Tool version 3.00 for Windows, University of Texas Health Science Center in San Antonio, TX, USA) by two experienced blinded evaluators. Mesial and distal values were averaged so as to have a single value for each implant. Bone loss around tilted and axial implants was compared by using paired Student’s t-test. Analysis of variance (ANOVA) was used to analyze bone level changes over time and P = 0.05 was considered as the level of significance.

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RESULTS From September 2011 to the same month of 2012, 7 healthy patients (5 women and 2 men; mean age 58 years; range 46-74 years) have been rehabilitated according to the RevitaliZe Patient Solutions. Five subjects were treated in both arches (4 of them during the same day) for a total of 12 immediately loaded fixed prosthesis (7 maxillae and 5 mandibles) supported by four implants. Four patients were smokers with a daily consumption of 4.7 cigarettes. Forty-eight Tapered Screw-Vent TSVT (Zimmer Dental Inc., Carlsbad, California, USA) implants with MTX®surface were placed and all of them were immediately loaded. Forty-four fixtures had a diameter of 3.7 mm, while length ranged from 10 to 16 mm. Posterior implants had a mesio-distal inclination ranging between 20 and 40 degrees according to anatomical limitation and local condition. No complication occurred during surgical or prosthetic phases and no fracture of the final prostheses or any screw loosening have been reported. The mean follow-up duration was 11.88 ± 2.38 months (range 9-16 months) and no implant or prosthetic failure occurred, resulting in 100% survival rates. Peri-implant bone loss after 1-year follow-up could be evaluated for 7 arches (n = 14 implants per group) and this parameter averaged 1.02 ± 0.10 mm and 1.02 ± 0.08 mm for axial and tilted implants, respectively. Such difference was not statistically significant (p > .05). Plaque and bleeding scores were recorded after 6 months of loading for all prosthesis and they were 12.08 ± 5.33 and 9.58 ± 5.03, respectively. All patients completed the questionnaire for satisfaction. Aesthetic, phonetics and masticatory function were judged as excellent or very good by all of them.

DISCUSSION The purpose of this paper was to report preliminary outcomes of immediate implant-supported fixed bridges for edentulous patients or for subjects who will become edentulous due to a failing dentition. Seven patients for a total of 15 arches were treated according to the RevitaliZe Patient Solutions, consisting on a functional screw-retained metal reinforced provisional restoration delivered within 24 hours from the placement of two axial and two tilted fixtures.

VOLUME 30  •  NUMBER 2bis  •  2014

A g n i n i A , S a l a m a MA , M as t r o r o sa A g n i n i A , S a l a m a H , S ta p p e r t C FJ, R o m e o D

The results of 100% implant and prosthetic survival rates after a mean follow-up of 12 months are in line with similar studies with immediate loading protocols9-12,22. Agnini and coworkers17 reported 98.02% implant survival rate for 202 fixtures followed for an average of 44 months. In this study, 1-year marginal bone loss of 1.02 ± 0.10 mm and 1.02 ± 0.08 mm was registered for 14 axial and 14 tilted implants, respectively. These results are similar to the data of a recent study from the same authors where the same implant morphology was used but a variation of the implant collar exists. Tapered Screw-Vent TSV fixtures placed in that study differ from the Tapered Screw-Vent TSVT version used in this investigation for the presence of a 0.5 mm MTX® Microtextured Surface followed by 1.8 mm of Textured Microgrooves. The full textured neck placed in sub-crestal position should increased the amount and stability of the fibrin clot, leading to a major bone formation, while the role of the six microgrooves is to augment fixture primary stability in the most coronal area, specially in soft bone, and to provide more surface for new bone formation. However, a larger number of patients with a longer follow-up is necessary to draw conclusions about a possible role of TSVT implants in marginal bone level maintenance. In this protocol posterior implants are tilted with an inclination ranging between 20 to 40 degrees. A 15 and 30 degrees tapered angulated abutments can correct up to 30 and 45 degrees implants inclination, respectively, thanks to the 15 degrees conical shape of their platform. The use of this abutments results in a most favorable orientation of the prosthetic screw. Great results in terms of esthetics and function were registered from all patients, especially in case of zirconia frameworks. The vestibular part of frontal teeth were left open to dental technician veneering ability for the characterization of every single element. The fact that the occlusal surface was part of the monolithic block decrease the working time for the technician, with a reduction of economic cost.

CONCLUSION The preliminary results of the present prospective study are positive and in agreement with similar studies. No incidence of surgical or prosthetic complications, high implant and prosthesis survival rates and improved hygienic level throughout the study reveal

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that RevitaliZe Patient Solutions is a predictable technique for the rehabilitation of complete arches. However, long-term clinical data are necessary to confirm this statement.

REFERENCES   1. Esposito M, Grusovin MG, Achille H, Coulthard P, Worthington HV. Interventions for replacing missing teeth: different times for loading dental implants. Cochrane Database of Systematic Reviews 2009 Jan 21 CD003878. Chichester, UK: John Wiley & Sons Ltd.   2. Papaspyridakos P, Mokti M, Chen GJ, Benic GI, Gallucci GO, Chronopoulos V. Implant and prosthodontic survival rates with implant fixed complete dental prostheses in the edentulous mandible after at least 5 years: a systematic review. Clin Implant Dent Relat Res 2013, Jan 11. doi:10.1111/cid.12036   3. Gallucci GO, Morton D, Weber H-P. Loading protocols for dental implants in edentulous patients. Int J Oral Maxillofac Implants 2009;24:132-146.   4. Javed F, Romanos GE. The role of primary stability for successful immediate loading of dental implants. A literature review. Journal of Dentistry 2010;38:612-620.   5. Marquezan M, Osòrio A, Sant’Anna E, Souza MM, Maia L. Does bone mineral density influence the primary stability of dental implants ? A systematic review. Clin Oral Implants Res 2012;23:767-774.   6. Bahat O, Sullivan RM. Parameters for successful implant integration revisited part I: immediate loading considered in light of the original prerequisites for osseointegration. Clin Implant Dent Relat Res 2010;12(Suppl 1):e2-12.   7. Ghoul WE, Chidiac JJ. Prosthetic requirements for immediate implant loading: a review. J Prosthodont 2012;21(2):141-154.   8. Strub JR, Jurdzik BA, Tuna T. Prognosis of immediately loaded implants and their restorations: a systematic literature review. J Oral Rahabilitation 2012;39:704-717.   9. Del Fabbro M, Bellini CM, Romeo D, Francetti L. Tilted implants for the rehabilitation of edentulous jaws. A systematic review. Clin Implant Dent Relat Res 2010, May 13 doi: 10.1111/j.1708-8208.2010.00288.x. 10. Agliardi E, Panigatti S, Clericò M, Villa C, Malò P. Immediate rehabilitation of the edentulous jaws with full prostheses supported by four implants: interim results of a single cohort prospective study. Clinical Oral Implant Research 2010;21:459-465. 11. Weinstein R, Agliardi E, Del Fabbro M, Romeo D, Francetti L. Immediate rehabilitation of the extremely mandible with fixed full-prosthesis supported by four implants. Clin Implant Dent Relat Res 2012;14:434441. 12. Malò P, de Araújo Nobre M, Lopes A, Moss SM, Molina GJ. A Longitudinal study of the survival of All-on-Four implants in the mandible with up to 10 years of follow-up. Journal of American Dental Association 2011;142:310-320. 13. Francetti L, Romeo D, Corbella S, Taschieri S, Del Fabbro M. Bone level changes around axial and tilted implants in full arch fixed immediate restorations. A 5-year prospective study. Clin Implant Dent Relat Res 2012;14:646-654. 14. Keats AS. The ASA classification of physical status – A Recapitulation. Anestesiology 1978;4:233-236. 15. Biscaro L, Becattelli A, Poggio PM, Soattin M, Rossini F. The one-model technique: a new method for immediate loading with fixed prostheses in edentulous or potentially edentulous jaws. Int J Periodontics Restorative Dent 2009; 29: 307-313. 16. Lekholm U, Zarb GA. Patient selection and preparation. In: Brånemark P-I, Zarb GA, Albrektsson T, eds. Tissue-integrated prostheses: osseontegration in clinical dentistry. Chicago, IL:Quintessence,1985:199-209. 17. Agnini A, Agnini AM, Romeo D, Chiesi M, PAriente L, Stappert CF. Clinical investigation on axial versus tilted implants for immediate fixed rehabilitation of edentulous arches: preliminary results of a single cohort study. Clinical Implant Detn Relat Res 2012, Nov 21 doi:10.1111/ cid.12020

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18. Sacca S, Coulthard P. Implant failure: etiology and complications. Med Oral Patol Oral Cir Bucal 2011;16:42-44. 19. Esposito M, Hirsch JM, Lekholm U, Thomsen P. Biological factors contributing to failures of osseointegrated oral implants. (II). Etiopathogenesis. Eur J Oral Sci 1998;106:721-764. 20. Zurdo J, Romão C, Wennström JL. Survival and complication rates of implant-supported fixed partial dentures with cantilevers: a systematic review. Clin Oral Implants Res 2009;20:59-66.

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21. Dierens M, Collaert B, Deschepper E, Browaeys H, Klinge B, De Bruyn H (2009). Patient-centered outcome of immediately loaded implants in the rehabilitation of fully edentulous jaws. Clin Oral Implants Res 2009;20:1070-7. 22. Agliardi E, Pozzi A, Stappert CFJ, Benzi R, Romeo D, Gherlone E. Immediate fixed rehabilitation of the edentulous maxilla: a prospective clinical and radiological study after 3 years of loading. Clinical Implant Dent Relat Res 2012, Aug 9. Doi:10.1111/j.1708-8208.2012.00482.x.

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Augmentation osseuse latérale à l’aide d’un bloc cortico-spongieux allogénique (Puros®, Zimmer dental) et régénération osseuse guidée (ROG) suivie de la pose d’un implant selon une approche étagée : cas cliniques Argibay Lorenzo Olalla*, Carral Freire Cristina**, Blanco Carrión Juan*** Objectif : illustrer, d’un point de vue clinique et radiographique, deux cas cliniques d’augmentation de crête latérale à l’aide d’un nouveau matériau de greffe osseuse, Puros®(Zimmer Dental, Inc, Carlsbad, CA). Ce matériau a été préalablement préparé par un nouveau procédé de traitement et de stérilisation, Tutoplast (Tutogen Medical, Inc, Alachua, Fl), l’augmentation étant suivie de la pose d’implants selon une approche étagée. Matériels et méthodes : Deux patients ont été traités. Les procédures d’augmentation de crête latérale alvéolaire ont été réalisées dans une zone édentée au moyen d’un nouveau matériau de greffe osseuse, Puros®(Zimmer Dental, Inc, Carlsbad, CA). Les implants ont été posés en position prothétiquement idéale au bout de 6 mois de cicatrisation. 3 mois plus tard, les restaurations définitives ont été posées. Des clichés radiographiques ont été obtenus immédiatement avant la chirurgie, puis 6 mois et 1 an après celle-ci. Résultats : après six mois de cicatrisation, le matériau greffé était parfaitement intégré dans le site receveur, aussi bien d’un point de vue clinique que radiographique. Les implants ont été posés sans complications, en position prothétiquement idéale. Au bout d’un an de cicatrisation, et 6 mois après la pose des implants et de la prothèse, les résultats étaient stables. Aucun signe de changements structurels ou de résorption osseuse n’était constaté. Conclusions : 6 mois après la mise en charge, les résultats esthétiques et fonctionnels de ces cas cliniques où les implants avaient été posés après régénération de crête latérale par le matériau d’allogreffe Puros® (Zimmer Dental, Inc, Carlsbad, CA) et la membrane en péricarde CopiOs étaient excellents, ce qui était par ailleurs confirmé par les résultats cliniques et radiologiques. N’empêche que l’évidence scientifique est encore insuffisante pour valider cette technique. Dès lors, il faudra réaliser des essais cliniques randomisés. Mots-clés : Augmentation osseuse latérale, Allogreffe, Régénération osseuse, Implants dentaires, Substituts osseux.

INTRODUCTION Les implants en titane sont considérés comme un traitement efficace et prévisible de l’édentement partiel et total1.

* Master en Parodontologie. Université de Saint-Jacques-deCompostelle. ** Master en Parodontologie. Université de Saint-Jacques-deCompostelle. *** MD, DDS, PhD, Professeur. Université de Saint-Jacques-deCompostelle. Coordonnées de l’auteur : Argibay Lorenzo, Olalla C/Entrerrios sn 15702 Santiago de Compostela, A Coruña, Espagne. Tél. 0034 981 571 826

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En implantologie, il est désormais pratique courante de poser les implants selon les besoins anticipés de la restauration plutôt qu’en fonction de l’os disponible. Pour que l’implant soit posé en position prothétiquement idéale, il faut aussi que le site receveur dispose d’une largeur de la crête et d’une hauteur osseuse répondant à des exigences minimales. Il existe de nombreuses techniques qui permettent d’obtenir une augmentation osseuse latérale, soit en même temps que la pose d’implants, soit avant celle-ci, au bout d’une période de cicatrisation. Ces procédures impliquaient le recours à la greffe osseuse avec différents types de greffons (autogreffes, allogreffes, xénogreffes ou substituts osseux), seuls ou en combinaison avec des procédures de régénération osseuse guidée (ROG) et des techniques d’expansion crestale.

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L’os allogénique a des caractéristiques ostéoconductrices semblables à celles des greffons autologues. Dès lors, il a été utilisé comme alternative à l’os autologue dans les greffes osseuses2. Les particules spongieuses allogéniques minéralisées (MCBA) ont été utilisées comme matériau de greffe dans le traitement des défauts de l’os parodontal, mais également en chirurgie bucco-dentaire pour les sites post-extractionnels et pour les procédures d’augmentation de crête, avant la pose d’implants ou simultanément à celle-ci. Le MCBA est produit osseux d’origine humaine prélevé sur donneur décédé, puis traité et stérilisé. Cet article vise à illustrer, d’un point de vue clinique et radiographique, deux cas cliniques d’augmentation de crête latérale à l’aide d’une nouvelle forme de ce matériau de greffe osseuse, Puros®(Zimmer Dental, Inc, Carlsbad, CA). Ce matériau a été préalablement préparé par un nouveau procédé de traitement et de stérilisation, Tutoplast (Tutogen Medical, Inc, Alachua, Fl), l’augmentation étant suivie de la pose secondaire d’implants dentaires.

MATÉRIELS ET MÉTHODES 1er CAS Patient : une femme de 56 ans, non fumeuse, en bonne santé systémique, présentant à l’examen de nombreux éléments manquants perdus essentiellement pour des raisons parodontales, au début de l’adolescence. L’examen clinique et les radiographies ont montré une perte osseuse sévère dans les zones édentées (Fig. 1). Toutes les différentes alternatives de traitement ont été discutées de façon approfondie. Un guide chirurgical a été réalisé pour pouvoir poser les implants en position prothétiquement idéale. Lors de la première procédure chirurgicale, cce guide a été utilisé pour identifier les zones qui devaient être régénérées, alors que dans le deuxième temps chirurgical il a servi à la pose des implants. La greffe osseuse étant nécessaire pour développer un volume osseux suffisant pour la pose d’implants, la patiente a préféré une allogreffe, pour s’épargner un

Fig. 1 Vue clinique intrabuccale. Zones édentées.

a

b

Figg. 2a,b Vue clinique intrabuccale. Zones édentées, vue occlusale. Evaluation radiographique initiale.

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deuxième acte chirurgical pour le prélèvement d’un greffon d’os autogène. Procédure chirurgicale : après avoir anesthésié la patiente par des infiltrations locales, il a été pratiqué une incision médio-crestale. Un lambeau mucopériosté a été soulevé pour exposer la crête alvéolaire résiduelle, qui mesurait 3 mm de large (Fig. 3). L’allogreffe stérile (Puros Block Allograft®, Zimmer Dental, Inc, Carlsbad, CA) a été hydratée. Elle a été retirée de son emballage et placée dans le cylindre d’une seringue sans embout. Après avoir extrait le piston, la seringue a été remplie de solution stérile jusqu’à couvrir entièrement le greffon. L’air excédentaire a été évacué, en bouchant l’embout du cylindre. Puis, par un mouvement de retrait du piston, l’hydratation par la solution stérile du greffon allogénique a été optimisée. L’air excédentaire a été évacué encore une fois, et cette opération a été répétée pendant 3 à 5 minutes avant de passer à la phase de préparation (Fig. 4). L’allogreffe a été modelée sous irrigation, avec une pièce à main haute vitesse (Ti-Max Z, NSK) et une fraise, de façon à assurer la stabilité du greffon et à maximiser

le contact avec l’os. Les angles corticaux tranchants du greffon ont été arrondis pour minimiser le traumatisme des tissus mous. La couche de particules spongieuses a été adaptée au site receveur (Fig. 5). Nous avons essayé de préserver la surface de la corticale autant que possible, afin de pouvoir disposer d’une surface dense pour la fixation du greffon. Des micro-perforations ont été réalisées dans la corticale du site receveur, afin de provoquer un saignement. Ce saignement pourrait contribuer à la prolifération des facteurs de croissance et des plaquettes, qui jouent un rôle essentiel dans la cicatrisation et dans la revascularisation (Fig. 6). Des trous d’accès ont été préparés au travers du greffon par un foret de 1,5 mm de diamètre (Straumann AG, Bâle, Suisse), jusqu’à l’os receveur sous-jacent, afin d’y loger les vis de fixation. Ceci fait, le bloc a été placé dans le site chirurgical, où il a été stabilisé à l’aide de deux mini-vis de 12 mm (Straumann AG, Bâle, Suisse) pour prévenir la rotation du greffon (Fig. 7).

Fig. 3 La crête alvéolaire résiduelle.

Fig. 4 Le bloc d’allogreffe Puros® dans le cylindre de la seringue avec la solution.

Fig. 5  L’allogreffe a été modelée de façon à assurer la stabilité du greffon et à maximiser le contact osseux.

Fig. 6 Des trous sont transpercés dans l’os cortical receveur afin de provoquer un saignement.

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a

b

c

d

Figg. 7a-d Le bloc préparé est placé dans le site chirurgical et stabilisé par des mini-vis. Fig. 8 Le site greffé est entièrement couvert d’une membrane en péricarde (CopiOs®).

a

b

Figg. 9a,b Dissection du périoste et suture des lambeaux.

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Fig. 11 Deuxième chirurgie. Pose de l’implant.

Fig. 12 Sutures.

Fig. 10 Évaluation radiologique du greffon à 6 mois.

Le greffon a été ensuite soigneusement détouré dans la cavité buccale, afin d’éliminer tous les bords ou les angles tranchants qui pourraient contribuer aux complications des tissus mous. Autour du bloc, les espaces vides ont été remplis avec des particules osseuses (particules

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corticales Puros, Zimmer Dental, Inc, Carlsbad, CA). Le site greffé a été entièrement recouvert d’une membrane en péricarde (membrane CopiOs Pericardium, Zimmer Dental, Inc, Carlsbad, CA.) (Fig. 8). Nous avons réalisé une fermeture sans tension des tissus mous (Fig. 9). En post-opératoire, la patiente a reçu des antibiotiques, des bains de bouche antimicrobiens et un traitement antalgique. La cicatrisation post-opératoire s’est déroulée sans histoire et sans signes cliniques d’infection, déhiscence ou problèmes cliniques. La séance de pose d’implants a été prévue 6 mois plus tard. Avant d’exposer le site, une radiographie a été réalisée afin d’évaluer l’incorporation du bloc cortico-spongieux (I-CAT, système d’imagerie dentaire Cone Beam en 3-D) (Fig. 10). Le site a été exposé sous anesthésie locale, ce qui a permis de découvrir un bloc bien intégré, désormais incorporé dans l’os environnant. Les vis de fixation ont été retirées. Après la procédure d’augmentation, la largeur de la crête avait atteint les 9 mm. Le site implantaire a été préparé par un forage séquentiel sous irrigation selon le

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a

Fig. 14  Crête alvéolaire résiduelle.

b Figg. 13a,b Examen clinique et radiologique initial.

protocole standard (Straumann Dental Implant System, Bâle, Suisse) (Fig. 11). 2e CAS Patient : dans ce cas, nous avons traité une femme de 55 ans, en bonne santé systémique et totalement édentée. L’examen clinique et les radiographies ont montré une perte osseuse sévère dans les zones édentées. Toutes les différentes alternatives de traitement ont été discutées de façon approfondie. Une greffe

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Fig. 15  Stabilisation du greffon et contact osseux.

osseuse était nécessaire pour pouvoir placer correctement les implants (sur la base de considérations prothétiques) (Fig. 13). Nous avons décidé de réaliser une greffe d’os autogène sur le côté droit, et une allogreffe sur le côté gauche (Puros Block Allograft®, Zimmer Dental, Inc, Carlsbad, CA). Procédure chirurgicale  : après avoir anesthésié la patiente par des infiltrations locales, il a été pratiqué une incision médio-crestale. Un lambeau mucopériosté a été soulevé pour exposer la crête alvéolaire résiduelle, qui mesurait de 2 à 3 mm de large (Fig. 14). L’allogreffe stérile (Puros Block Allograft®, Zimmer Dental, Inc, Carlsbad, CA) a été hydratée selon la procédure décrite dans le cas précédent. Des trous d’accès ont été préparés au travers du greffon par un foret de 1,5 mm de diamètre (Straumann AG, Bâle, Suisse), jusqu’à l’os receveur sous-jacent, afin d’y loger les vis de fixation. Ceci fait, le bloc a été placé dans le site chirurgical, où il a été stabilisé à l’aide de deux mini-vis (Straumann AG, Bâle, Suisse) pour prévenir la rotation du greffon (Fig. 7). Du côté controlatéral, nous avons utilisé la zone postérieure de la mandibule comme deuxième site chirurgical, afin d’y prélever un greffon d’os autogène. Ce greffon a été d’abord préparé, puis fixé, également avec des mini-vis (Fig.16). Le modelage final du greffon a été réalisé dans la cavité buccale. Autour du bloc, les espaces vides ont été remplis avec des particules osseuses (particules corti-

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a

b

Figg. 16a,b Greffon autologue provenant de la mandibule.

Fig. 17 Particules osseuses dans les espaces autour du matériau greffé et du greffon autologue.

Fig. 18 Sutures.

Fig. 19 Examen radiologique à 6 mois (greffon autologue).

Fig. 20 Examen radiologique à 6 mois (Allogreffe).

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Fig. 22 Sutures. Fig. 21 Pose des implants (deuxième chirurgie).

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Fig. 23 Résultat final.

Fig. 24 Restauration finale (vue clinique).

cales Puros®, Zimmer Dental, Inc, Carlsbad, CA) (Fig.17). Le tout a été couvert d’une membrane en péricarde (membrane CopiOs Pericardium Zimmer Dental, Inc, Carlsbad, CA.) Après la fermeture des tissus mous sans tension, nous avons enfin suturé les lambeaux (Fig. 18). En post-opératoire, la patiente a reçu des antibiotiques, des bains de bouche antimicrobiens et un traitement antalgique. La cicatrisation post-opératoire s’est déroulée sans histoire et sans signes cliniques d’infection, déhiscence ou problèmes cliniques. La séance de pose d’implants a été prévue 6 mois plus tard. Avant d’exposer le site, des radiographies ont été réalisées afin d’évaluer l’incorporation des greffons (I-CAT, système d’imagerie dentaire Cone Beam en 3-D) (Fig. 19-20). Le site a été exposé sous anesthésie locale, ce qui a permis de découvrir un bloc bien intégré, désormais incorporé dans l’os environnant. Après avoir retiré les vis de fixation, l’étape suivante a été la pose guidée d’implants, à l’aide du guide chirurgical (Straumann® Dental Implant System, Bâle, Suisse) (Fig. 21)

Pendant la pose des implants, il n’y a pas eu de complications chirurgicales au niveau de l’os régénéré. Ceci fait, les lambeaux ont été suturés (Fig. 22) Quatre semaines plus tard, la patiente a reçu son provisoire, et 10 mois plus tard la prothèse définitive, qui a pu être posée de façon optimale (Fig. 23).

RÉSULTATS Ces cas décrivent la réponse de cicatrisation après une procédure d’augmentation de crête latérale par les particules d’os spongieux minéralisé Puros®(Zimmer Dental, Inc, Carlsbad, CA), suivie par la pose secondaire d’implants et par la pose d’une prothèse. Après six mois de cicatrisation, le matériau greffé était parfaitement intégré dans le site receveur, aussi bien d’un point de vue clinique que radiographique. Les implants ont été posés sans complications, en position prothétiquement idéale. Au bout d’un an de cicatrisation, et 6 mois après la pose des implants et de la prothèse, les résultats étaient

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stables. Aucun signe de changements structurels ou de résorption osseuse n’était constaté.

DISCUSSION 6 mois après la mise en charge, les résultats esthétiques et fonctionnels de ces cas cliniques où les implants ont été posés après régénération de crête latérale par le matériau d’allogreffe Puros® (Zimmer Dental, Inc, Carlsbad, CA) et la membrane en péricarde CopiOs étaient excellents, ce qui était par ailleurs confirmé par les résultats cliniques et radiologiques. Une greffe réussie implique un processus de revascularisation concomitante et le remplacement du greffon par l’os de l’hôte, sans pertes significatives en termes de force et de volume. Le volume osseux est important pour de nombreux facteurs liés à la santé buccale et au traitement de restauration potentiel, y compris la position et la localisation des implants posés, leur succès ou leur échec, et l’esthétique des restaurations définitives. L’utilisation des allogreffes a des avantages, dont notamment l’absence de limites quant au nombre de greffons disponibles, l’élimination du deuxième site chirurgical pour le prélèvement d’os autologue et la possibilité d’éviter la morbidité du site donneur. L’os des donneurs décédés utilisé dans Puros est fourni par une banque des tissus certifiée (selon législation en vigueur du pays). Le matériau allogénique, qui consiste en de l’os cortical provenant de donneurs humains, a été soumis à un procédé breveté en 5 étapes (Tutoplast) afin d’assurer sa sécurité biologique. Les phases de ce procédé sont les suivantes  : délipidation (élimination des graisses), traitement osmotique, oxydation au péroxyde d’hydrogène, déshydratation par solvant et irradiation par rayonnement gamma à faible dose. Ce traitement inactive le virus du VIH et l’agent responsable de la maladie

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de Creutzfeldt-Jakob. Dans une étude expérimentale des tissus prélevés chez des sujets décédés de SIDA et d’hépatite C, ne présentaient plus aucun signe infectieux à l’issue du traitement5. Le site greffé a été entièrement recouvert d’une membrane en péricarde (membrane CopiOs Pericardium, Zimmer Dental, Inc, Carlsbad, CA.) La membrane en péricarde CopiOs assure une barrière à long terme. Selon une étude animale de Rothamel et ses coll.6, le temps de résorption de la membrane est 20 à 24 semaines. Selon ces Auteurs, la membrane en péricarde favorise l’adhésion et la prolifération des fibroblastes du ligament parodontal humain, ainsi que celles des ostéoblastes humains. La membrane en péricarde CopiOs est également traitée selon les différentes étapes du procédé breveté Tutoplast. Néanmoins les critères scientifiques sont encore insuffisants pour valider cette technique. Dès lors, il faudra réaliser des essais cliniques randomisés.

Bibliographie   1. Alberktsson T, Zarb G, Whortington P &Ericsson A R. the long term efficacy of currently use dental implants: a review and proposed criteria of success. International Journal of Oral and Maxillofacial Implants. 1986; 1:11-25.   2. Becker W, Urist M, Becker BE. Clinical and histological observations of the sites implanted with intraoral autologous bone grafts or allografts. 15 human case reports. J Periodontol 1996; 67: 1025-33.   3. Keith DJ, Petrungaro SS, ELwell CW, Caputo C, Scopf C. Clinical and histological evaluation of a mineralized block allograft: results from the development period (2001-2004). Int J Periodontics and Restorative Dent 2006; 26: 321-27.   4. Froum SJ, Tarnow DP, Wallace SS. The use of a mineralized allograft for sinus augmentation: an interim histological case report from a prospective clinical study. Compend Contin Educ Dent 2005; 26:81-86.   5. Schopf C, Diaber W, Tadiz D. Tutoplast poocessed allografts and xenografts. 3D Block technique from image diagnostics to block graft bone regeneration. Milano, Italy: RC Libri SRL 2005; 53-75.   6. Rothamel D, Schwarz F, Sager M, Herten M, Sculean A, Becker J. Biodegradation of differently cross linked collagen membranes. An experimental study in the rat. Clin Oral Impl Res 2005; 16: 369-78.

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Digital Dentistry meets Implantology The Munich Implant Concept - A case report Florian Beuer*, Josef Schweiger*, Jan-Frederik Güth* The digital fabrication of dental restorations has become a standard procedure during the last decade. Intraoral scanning devices are about to be established in general dental offices. However, up until now, digital fabrication has solely concerned the replacing of analogue workflows without further benefits. The presented concept for implant-supported single crowns describes a digital approach without a physical model from implant placement to delivery of the final restoration in 2 appointments. Here, the benefits of digital fabrication and the unique way to scan the implant right after placement give an additional value that would not be achieved by analogue techniques. In addition to financial benefits, it represents the biologically advantageous, one-abutment, on-time approach with customized screw-retained, full-contour crowns made from lithium-disilicate. Key Words: Dental implant, Digital dentistry, One-abutment one-time, Biological.

Introduction During the last decades, implant supported restorations have significantly changed prosthetic treatment concepts and their reliability could be proved scientifically.1-4 In particular, single implants help to avoid sacrificing natural tooth structure when fixed dental prostheses (FDPs) supported from adjacent teeth can be avoided. However, to achieve a functional, esthetic, and biological long-term success, several clinical considerations have to be taken into account, of which the soft tissue conditions around the implant can be considered as one of the most important factors.5 The interface, which is established during soft tissue healing between the peri-implant mucosa and the * Dental School of the Ludwig-Maximilian University of Munich. Department of Prosthodontics - Goethestr 70 - 80336 Munich, Germany. Correspondence: Priv. Doz. Dr. Florian Beuer Dental School of the Ludwig-Maximilian University of Munich Department of Prosthodontics Goethestr 70 - 80336 Munich Tel. +49 89 5160 9558 - Fax +49 89 5160 9502 E-mail: [email protected]

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implant/abutment, consists of an epithelium and a connective tissue component.6 Berglundh et al. reported a length of approximately 2 mm for the junctional epithelium and a height of 1-2 mm for the connective tissue zone, resulting in a total transmucosal attachment of 3-4 mm.7 Several technical factors might possibly influence the condition of this critical peri-implant mucosa, such as the material of the abutment, the veneering material, the fit of the abutment or a platform-switch.8,9 For example, different abutment materials lead to different histological findings of the peri-implant mucosa. Thus, titanium and zirconia were reported to show favorable quality of the attachment between implant and mucosa compared to gold-alloys. In particular, an apical shift of the mucosal barrier and the marginal bone was shown for gold-alloy abutments after 5 months in an animal study.10 On the other hand, veneering porcelain failed to establish a stable barrier resulting in recessions of the mucosa and bone resorption.11 Unfortunately, the influence of the match of the implant and the abutment on soft tissue stability and bone remodeling remains unclear at the moment. However, no negative effects of platform switching have been published. Furthermore, the clinical impact of the implant abutment connection cannot be stated clearly.12

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In contrast, some clinical procedures are known to influence the soft tissue around dental implants. For example, frequent probing at dental implants was shown to increase the pocket probing depths and markedly disrupted the epithelial and connective tissue attachment.13 Additionally, an elevation of a full flap (periosteum) leads to a substantial loss of hard tissues and therefore influences the soft tissue behavior.14 Furthermore, the prosthetic treatment concept was reported to influence the stability of the soft tissues. Repeated abutment change was associated with a disruption of the mucosal seal and an increase of the dimension of the transmucosal barrier in an animal study. If zirconia was used as abutment material, the effect was even stronger. As such, from a histological point of view, abutments should not be changed after once they have been placed.15 In this context, interesting concepts – e.g., the “one abutment-one time concept” – have been already described. Against a control group using provisional abutments, the “one abutment-one time” group showed significantly less bone loss at the 18 months and 3 years recall after implant placement.16 Today, the computer-aided design (CAD)/computer aided manufacturing (CAM) of implant abutments has become a new standard for customized abutments. However, using digital technology for fabrication of dental restorations requires the digitalization of the oral situation. This can be done either by direct digitalization, using an intraoral scanning device, or by indirect digitalization of a plaster model in the dental laboratory.17 Because of the multiple potential sources of error during the conventional way, including conventional impression, plaster model, and indirect digi-

talization, the direct digitalization using an intraoral scanner seems to be the most logical way to access the digital workflow and CAD/CAM.18-20 As a whole, the digital workflow offers the possibility to facilitate the daily procedures and offers new, innovative treatment strategies that provide advantages for dentists, dental technicians, and patients. Against this background, this report introduces the Munich Implant concept (MIC®) that describes the treatment of a patient with an implant-supported, fullcontour crown within two appointments without any physical model, using intraoral scanning and CAD/CAM technology.

CASE REPORT Anamnesis and Preoperative Procedure A 44-year old male patient was referred to the Department of Prosthodontics with a periapical ostitis after endodontical treatment of his mandibulary right first molar (FDI 46, Fig. 1). The severe destruction and heavy inflammation made the extraction of the tooth necessary. After discussing the alternative treatments, the patient decided to have a single-tooth implant and gave his informed consent. Ten weeks after extraction, the soft tissue was healed (Fig. 2) and a cone-beam computer tomography (CT) of the site was made to receive three-dimensional information about the soft and hard tissues (CS 9300, Carestream Dental, Rochester, NY, USA) at the desired implant position.

Fig 2 Pre-operative situation 10 weeks after extraction of tooth FDI 46.

Fig 1 X-ray of the preoperative findings: Apical ostitis at tooth 46 after root canal treatment and severe coronal destruction lead to the extraction of tooth.

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Fig 3 Datasets (maxilla, mandible and bite-registration) of the preoperative situation after intraoral scanning using the Zfx Intrascan.

Fig 4 Insertion of the implant during the first appointment (Trabecular Metal Implant, Zimmer Dental, Freiburg).

Fig 6 Dataset of the Scan body and adjacent teeth, that is to be superimposed with the preoperative scan-dataset. Fig 5 Scan body placed on the implant immediately after insertion. The Scan body and adjacent teeth were scanned by a powder-free Intraoral-Scanner (Zfx Intrascan, Zfx, Dachau) to register the implant position.

Appointment 1: Implant Surgery and Scanning The intraoral situation was digitized using an intraoral scanning device (Intrascan, Zfx, Dachau, Germany) to receive a dataset of the clinical situation (Fig. 3). This scan involved the mandible (gap and adjacent teeth), the maxilla, and a vestibular scan for bite-registration. The patient was instructed to take antibiotics (Amoxicillin, 1.000 mg t.i.d.) and 400 mg of Ibuprofen one hour before surgery to prevent inflammation and swelling. Ibuprofen was continued for 2 days. Right before surgery, the patient rinsed his mouth with a 0.2% chlorhexidine solution for 3 minutes21. A crestal incision in region 46 was followed by a sulcular incision at tooth 45 and tooth 47. A full-thickness flap was elevated, and all inflammatory and granulation tissue was debrided with a curette. For a tension-free wound closure, the periosteum was slitted at the basal of the flap, right at beginning of the surgery, to prevent bleeding by the time of the membrane placement at the end of the pro-

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cedure. An implant (length 10 mm, diameter 4.7 mm, Trabecular Metal, Zimmer Dental, Freiburg, Germany) was placed at the planned position (Fig. 4). After placement, a scan-body (experimental design, Zfx) was screwed to the primary stable implant to enable the direct digitalization of the implant position (Fig. 5). The precise fit of the scan-body could be controlled easily, and the scan was conducted within the “gingiva-extra” scan-mode. During scanning, it was of paramount importance to also scan the adjacent teeth to enable a superimposition of the scan-body-dataset with the situation scan, which was conducted prior to surgery (Fig. 6). After scanning, the scan body was removed, a covering screw was placed, and the wound was closed with a deep horizontal mattress and interrupted sutures (Prolene 6.0; Ethicon, Johnson & Johnson Medical, Norderstedt, Germany). A control x-ray was made (Fig. 7), and the patient was instructed on adequate behavior for the next days.

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Wound healing was uneventful; the sutures were removed 8 days after implant placement. Subsequently, the scandata was transferred online to the dental laboratory of the Department of Prosthodontics of the LMU Munich, where the crown was manufactured during the healing period. Laboratory The scan data were imported into a CAD-Software (Zfx-CAD-Software, Zfx) to design the final restoration (Fig. 8, 9). For the final restoration, the restorative team decided to deliver a full-contour crown made from lithium-disilicate (IPS e.max CAD, Ivoclar Vivadent, Schaan, FL), which was stained and glazed.22 The finalized crown was adhesively bonded (Multilink Implant, Ivoclar Vivadent, Schaan, FL) to a titanium insert (Fig. 10) in accordance to the manufacturer’s recommendations.23,24 Appointment 2: Re-entry and Delivery After 12 weeks of healing, the reentry of the implant took place, and the final crown was inserted. Therefore, only a mucosal flap was necessary, and the peri-

Fig 7 Post-surgery x-ray.

Fig 9 CAD of the full-contour crown.

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osteum could remain on the bone. The covering screw was removed; the implant was rinsed with isotonic sodium chloride solution and dried. The screw-retained crown was tried in, occlusal and proximal contacts were checked and adapted. The crown was polished in the dental laboratory according to the manufacturer’s recommendations and was cleaned in an ultrasonic bath. Before placing, the restoration was disinfected in 0.2% chlorhexidine solution. The crown was placed, and the screw was fixed with a torque moment of 20 Ncm. The soft-tissue was adapted to the crown with 2 papilla sutures (Prolene 6.0, Ethicon, Johnson & Johnson Medical, Norderstedt, Germany). Sutures were removed after uneventful healing after 6 days (Fig. 11). 18-month Recall At the 18-month follow-up, stable soft and hard tissue-conditions were found (Fig. 12, 13). The treatment outcome was met with full satisfaction of the patient. Unfortunately, the replacement of the adjacent crowns had to be postponed due to financial reasons.

Fig 8 Dataset after online-transfer to the dental laboratory and import to the dental CAD-Software (Zfx CAD Software, Zfx Dachau).

Fig 10  Milled full-contour crown from Lithium-Disilicate (IPS e.max CAD) in a pre-crystallized stage. After staining and glazing, the crown was adhesively bonded to the titanium insert, before delivery to the dental office.

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Fig 11  Inserted crown one week in situ before sutureremoval. Fig 12 18 month recall: The x-ray shows stable conditions of the bone around the implant and adjacent teeth.

Fig 13 18 month recall: Stable conditions of the soft-tissue around the implant-supported crown could be observed.

DISCUSSION Today, the CAD/CAM-supported fabrication of abutments and implant-supported restorations can be considered as the new standard.25,26 In consideration of the industrial quality of the applied materials and the almost unlimited design-opportunities regarding the emergence profile, the dimensions and angulation of the restorations have to be mentioned as the major advantage of this digital procedure. In addition to higher mechanical stability that can be achieved by CAD/CAM-fabricated restorations22, concepts that offer additional value to patients and practitioners mean further advantages of digital implant-supported prosthodontics.

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Regarding the MIC®, the fabrication of the restoration during the (closed) healing-phase of the implant rationalizes the treatment-procedure. The accuracy of the transfer of the implant position by an intraoral scan seems to be sufficient for single tooth implants.27 Also, the adjacent teeth and antagonists are directly digitized, which facilitates the transfer of the situation to the dental laboratory. Based on the authors’ experience, physical models are not necessary for that kind of single tooth-restoration. When using a transfer-post after the healing-period, the correct fit is often controlled by an x-ray. When optical scanning is carried out immediately after surgery, before the wound is closed, the fit of the scan-body can be easily controlled visually without radiation exposure. After placement of the restoration at the time of uncovering the implant, the healing of the soft-tissue takes place at the definitive restoration instead of at a healing abutment. Consequently, the emergence profile heals immediately toward an optimal shape. In contrast, standard healing abutments exhibit a round profile, which means that the cross section of the emergence profile has to be modified from round-shaped toward root-shaped before placement of the definitive restoration. This is achieved by repeated change of provisional restorations or continuously individualized healing-abutments to apply gentle pressure on the emergence profile.28 However, too much high pressure might cause a change of the mucosa that can lead to a loss of attached gingiva and recessions.29 Additionally, the immediate placement of the definitive restoration enables the formation of a long junctional epithelium between the restoration and softtissues that should not be separated again6,10,15,30. This sealing between the oral environment and the alveolar

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bone is an important factor for the long-term success of implant-supported restorations.9,30,31 In consideration of these findings less peri-implant inflammation can be expected when the junctional epithelium is not detached and injured. However, this has to be proven in animal experiments and clinical studies. Observed from Seen from the economic standpoint, the concept offers clear advantages for dentists and patients. On the one hand, the concept saves treatment time, yet the healing period does not have to be abbreviated. On the other hand, the MIC®-concept offers saving-potential regarding additional implant parts, as there is no need for transfer posts and healing-abutments. A screw-retained full contour crown from lithiumdisilicate on a titanium insert seems to be the perfect restorative approach for the presented concept. Even in cases where the soft-tissue-level might heal more apical from the planned level, there will be no aesthetical or functional disadvantages due to the continuous color and form of the restoration. However, the concept is also possible for cemented restorations with an abutment and a cemented crown.9 Overall, the Munich Implant Concept represents a concept with economical and biological advantages for practitioners and patients, and the ongoing integration of the digital workflow offers the potential of further enhancements and simplifications.

References   1. Akca K, Uysal S, Cehreli MC. Implant-tooth-supported fixed partial prostheses: correlations between in vivo occlusal bite forces and marginal bone reactions. Clin Oral Implants Res 2006; 17: 331-336.   2. Buser D, Mericske-Stern R, Bernard JP, et al. Long-term evaluation of non-submerged ITI implants. Part 1: 8-year life table analysis of a prospective multi-center study with 2359 implants. Clin Oral Implants Res 1997; 8: 161-172.   3. Kopp KC, Koslow AH, Abdo OS. Predictable implant placement with a diagnostic/surgical template and advanced radiographic imaging. J Prosthet Dent 2003; 89: 611-615.   4. Krennmair G, Krainhofner M, Waldenberger O, Piehslinger E. Dental implants as strategic supplementary abutments for implanttooth-supported telescopic crown-retained maxillary dentures: a retrospective follow-up study for up to 9 years. Int J Prosthodont 2007; 20: 617-622.   5. Happe A, Stimmelmayr M, Schlee M, Rothamel D. Surgical management of peri-implant soft tissue color mismatch caused by shinethrough effects of restorative materials: one-year follow-up. Int J Periodontics Restorative Dent 2013; 33: 81-88.   6. Zucchelli G, Mazzotti C, Mounssif I, Mele M, Stefanini M, Montebugnoli L. A novel surgical-prosthetic approach for soft tissue dehiscence coverage around single implant. Clin Oral Implants Res 2013; 24: 957-962.   7. Berglundh T, Lindhe J, Ericsson I, Marinello CP, Liljenberg B, Thomsen P. The soft tissue barrier at implants and teeth. Clin Oral Implants Res 1991; 2: 81-90.

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  8. Rodriguez AM, Rosenstiel SF. Esthetic considerations related to bone and soft tissue maintenance and development around dental implants: report of the Committee on Research in Fixed Prosthodontics of the American Academy of Fixed Prosthodontics. J Prosthet Dent 2012; 108: 259-267.   9. Esposito M, Maghaireh H, Grusovin MG, Ziounas I, Worthington HV. Soft tissue management for dental implants: what are the most effective techniques? A Cochrane systematic review. Eur J Oral Implantol 2012; 5: 221-238. 10. Welander M, Abrahamsson I, Berglundh T. The mucosal barrier at implant abutments of different materials. Clin Oral Implants Res 2008; 19: 635-641. 11. Abrahamsson I, Berglundh T, Glantz PO, Lindhe J. The mucosal attachment at different abutments. An experimental study in dogs. J Clin Periodontol 1998; 25: 721-727. 12. Schwarz F, Alcoforado G, Nelson K, et al. Impact of implant-abutment connection, positioning of the machined collar/MIC®rogap, and platform switching on crestal bone level changes. Camlog Foundation Consensus Report. Clin Oral Implants Res 2013. 13. Schwarz F, Mihatovic I, Ferrari D, Wieland M, Becker J. Influence of frequent clinical probing during the healing phase on healthy periimplant soft tissue formed at different titanium implant surfaces: a histomorphometrical study in dogs. J Clin Periodontol 2010; 37: 551-562. 14. Araujo MG, Lindhe J. Ridge alterations following tooth extraction with and without flap elevation: an experimental study in the dog. Clin Oral Implants Res 2009; 20: 545-549. 15. Becker K, Mihatovic I, Golubovic V, Schwarz F. Impact of abutment material and dis-/re-connection on soft and hard tissue changes at implants with platform-switching. J Clin Periodontol 2012; 39: 774780. 16. Canullo L, Bignozzi I, Cocchetto R, Cristalli MP, Iannello G. Immediate positioning of a definitive abutment versus repeated abutment replacements in post-extractive implants: 3-year follow-up of a randomised multicentre clinical trial. Eur J Oral Implantol 2010; 3: 285-296. 17. DIN13995:2010-02. Dentistry - Terminology of process chain for CAD/CAM-systems. 2010. 18. Christensen GJ. The challenge to conventional impressions. J Am Dent Assoc 2008; 139: 347-349. 19. Christensen GJ. The state of fixed prosthodontic impressions: room for improvement. J Am Dent Assoc 2005; 136: 343-346. 20. Christensen GJ. Laboratories want better impressions. J Am Dent Assoc 2007; 138: 527-529. 21. Stimmelmayr M, Stangl M, Edelhoff D, Beuer F. Clinical prospective study of a modified technique to extend the keratinized gingiva around implants in combination with ridge augmentation: oneyear results. Int J Oral Maxillofac Implants 2011; 26: 1094-1101. 22. Guess PC, Zavanelli RA, Silva NR, Bonfante EA, Coelho PG, Thompson VP. Monolithic CAD/CAM lithium disilicate versus veneered Y-TZP crowns: comparison of failure modes and reliability after fatigue. Int J Prosthodont 2010; 23: 434-442. 23. Stimmelmayr M, Edelhoff D, Guth JF, Erdelt K, Happe A, Beuer F. Wear at the titanium-titanium and the titanium-zirconia implantabutment interface: a comparative in vitro study. Dent Mater 2012; 28: 1215-1220. 24. Stimmelmayr M, Sagerer S, Erdelt K, Beuer F. In vitro fatigue and fracture strength testing of one-piece zirconia implant abutments and zirconia implant abutments connected to titanium cores. Int J Oral Maxillofac Implants 2013; 28: 488-493. 25. Beuer F, Schweiger J, Edelhoff D, Sorensen JA. Reconstruction of esthetics with a digital approach. Int J Periodontics Restorative Dent 2011; 31: 185-193. 26. Beuer F, Schweiger J, Edelhoff D. Digital dentistry: an overview of recent developments for CAD/CAM generated restorations. Br Dent J 2008; 204: 505-511. 27. Syrek A, Reich G, Ranftl D, Klein C, Cerny B, Brodesser J. Clinical evaluation of all-ceraMIC® crowns fabricated from intraoral digital impressions based on the principle of active wavefront sampling. J Dent 2010; 38: 553-559.

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28. Khoury F, Happe A. Soft tissue management in oral implantology: a review of surgical techniques for shaping an esthetic and functional peri-implant soft tissue structure. Quintessence Int 2000; 31: 483-499. 29. Stimmelmayr M, Allen EP, Reichert TE, Iglhaut G. Use of a combination epithelized-subepithelial connective tissue graft for closure and soft tissue augmentation of an extraction site following ridge preservation or implant placement: description of a technique. Int J Periodontics Restorative Dent 2010; 30: 375-381.

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30. Cochran DL, Mau LP, Higginbottom FL, et al. Soft and hard tissue histologic dimensions around dental implants in the canine restored with smaller-diameter abutments: a paradigm shift in periimplant biology. Int J Oral Maxillofac Implants 2013; 28: 494-502. 31. Cutrim ES, Peruzzo DC, Benatti B. Evaluation of soft tissues around single tooth implants in the anterior maxilla restored with cemented and screw-retained crowns. J Oral Implantol 2012; 38: 700-705.

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Surgical recommendations for allograft block grafting Oliver Blume*, Ole Richter**, Michael Back*, Thomas Müller-Hotop* Aim: Severe alveolar ridge deficiencies i.e. as a result of trauma and edentulism require bone augmentation before implant placement. Many different techniques and materials are available and have been investigated in the last 3 decades. One promising material group are block grafts for onlay block augmentation to reconstruct larger deficiencies of the jaw. Besides this, allogeneic block grafting becomes more and more attractive since allogeneic materials offers some advantages compared to autogenous bone blocks. However, there was still no surgical guide described in the literature to achieve predictable results with allograft blocks. This article discusses material properties, surgical recommendations and the influence of different treatment steps on the outcome of allogeneic block grafting. Key Words: Bone allograft, Block augmentation, Puros, Augmentations recommendations.

Introduction Dental implants are widely used in oral reconstruction for the replacement of missing teeth. In many cases pre-implant augmentative surgeries are necessary due to loss of bone volume followed by second stage implant placement. Bone regeneration of minor defects can be done according the the guided bone regeneration procedure with different bone graft materials in combination with resorbable or non-resorbable membranes1,2. For vertical and lateral augmentations of the jaw autogenous bone block have been harvested from different intra and extra-oral origins i.e. chin, ramus or iliac crest to reconstruct the ridge3-5. Despite autogenous bone is considered as the “gold standard”, harvesting of autogenous bone brings with several drawbacks. Clinical concerns are donor site morbidity, * Private practice, Tal 13, D 80331 Munich, Germany. ** Private practice, Johannisbollwerk 20, D 20459 Hamburg, Germany. Correspondence: Oliver Blume Tal 13, D 80331 Munich, Germany E-mail: [email protected]

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pain, swelling, bone quality and quantity depending on the donor site as well as graft resorption during healing and increased chair time6-9. For this reasons block grafts of synthetic10,11, xenogenic12,13 and allogeneic14-17 origin have been investigated. The most successful results have been obtained by choosing allogeneic bone blocks since allogeneic bone is similar to autogenous bone and possess a great biological quality18,19. It was shown earlier that performance of autogenous and allogeneic onlay grafts for ridge augmentation is comparable20. Today allogeneic block grafts have the advantages of unlimited supply and can be ordered in different packagings and compositions (cancellous or cortico-cancellous blocks). Different kinds of allogeneic materials are available depending on the harvesting and processing of the donor material. Going through this fresh-frozen21,22, freeze-dried23,24, mineralized25, demineralized 26 and solvent-preserved, gamma sterilized15,17,27 allogeneic materials have been investigated for their use in clinical dentistry. From a safety point of view allogeneic materials are sometimes considered as highly risky since reports were published describing disease transmissions28-30. Looking deeper in these articles shows that in the cases of disease transmissions non-purified, non-tested donor material was used.

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Today, harvesting and processing of allogeneic bone blocks is regulated by different government and industry entities depending of the national law31-33 and are considered as safe. Different surgeons chose different treatments steps while using autogenous or allogeneic blocks to rebuild defects of the jaw. Up to know no surgical protocol has been published dealing with the needs and risks of allograft block grafting in dental surgery to obtain predictable results. The aim of this article is to review and discuss different surgical steps reg. to their impact of the surgical outcome of block grafting with Puros® Allograft blocks.

Materials and Methods Puros Allograft Block Puros® Allograft blocks are processed by the Tutoplast® process. The process gently removes unwanted material such as fats, cells, antigens and inactivates pathogens, while preserving the bone mineral and collagen matrix34. The processing consists of six consecutive steps as shown in Fig 1. and was described in detail previously34. A key benefit of the Tutoplast process is the preservation of the natural composition of the collagen and bone mineral. Since the donated tissue is handled during processing at max. 37 °C there are no structural and chemical changes in the collagen and bone mineral structure as well as composition. Further the gentle solvent dehydration and the low dose gamma irradiation (dose < 25 kGy) ensure

that the natural cross links of the collagen fibers will be maintained 35-37 resulting in a sterile allograft with great biological and mechanical performances. The mechanical properties of the processed tissue are comparable with the non-processed raw material allowing an easy handling and shaping of the bone blocks38,39. Moreover the preserved collagen/mineral structure will be remodeled and revascularized into new, vital bone within 6–12 month by osteoclastic and osteoblastic activities17, 40. Block grafting – surgical procedure 1. Allograft block preparation During processing the bone blocks have been dehydrated resulting in a white, brittle bone block which could fracture during shaping. Based on this the bone blocks have to re-wetted prior shaping in sterile saline or water. An easy and effective way doing this is to place the bone block into a syringe and draw sterile saline into the syringe until the block graft is completely covered. By pulling on the plunger of the syringe a negative pressure will be applied and air trapped in the trabecular structure of the graft begins to expel. This procedure has to be repeated several times till all bubbles have been removed (Fig 2). The block should be placed in saline solution for additional 10 – 15 min to get fully saturated. The fully wetted block is hydrophilic allowing easy penetration of blood if placed at the recipient site.

2. Preparation of recipient site and block shaping The recipient site has to be evaluated for hard and soft tissue deficiencies, aesthetic concerns and health

Fig 1  Tutoplast processing of Puros Allografts.

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Fig 3 Midcrestal inscision with one vertical releasing incision to raise a full thickness flap.

Fig 2 Rehydration of an allograft block in saline.

Fig 4 Shaping of the rehydrated allograft block.

status of the adjacent teeth - if there are any. An adequate incision design should be chosen to raise a flap allowing access to the surgical field and to ensure a tension-free closure after grafting. In fact flap design is a critical aspect in the entire grafting procedure since esthetic aspects play a decisive role, especially in the anterior maxilla. The surgeon should know biotype, soft tissue thickness, soft tissue amount and consider that larger hard tissue volumes have to be covered after bone grafting to decide which incision technique ensures a complete covering. Several types of incisions are known to raise either full thickness or split-flaps such as midcrestal, lingual, vestibular incisions with/ without vertical releasing incisions41,42. By choosing a midcrestal incision extension of the incision at least one tooth mesial and distal of the recipient site is recommended (Fig 3). If scoring of the periosteum is considered to ensure a tension-free adaption of the flap some colleagues

incise periosteum immediately after raising the flap to allow time for hemostasis enabling good visibility of the surgical field, easier placement of particulate graft material and a membrane. However, since incision and flap design can impact the vascularization of the flap an appropriate technique is recommended to avoid flap necrosis if blood supply becomes diminished43. Both the recipient site and the block graft should be shaped to achieve close approximation of their surfaces since intimidate contact is mandatory for incorporation of the graft and success of the entire grafting procedure. (1) The wetted allograft block can be shaped with different rotating or cutting instruments with minimum risk of fracture. Care has to be taken that shaping will be done under saline solution to avoid heating of the block and denaturation of the collagen matrix (Fig 4). (2) At the recipient sites preparation includes decortication and perforation of the host bone to promote blood supply to the graft. If sufficient host bone is pres-

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ent decortication can be continued in a more aggressive way to prepare a definitive inlay site. The inlay technique provides a higher contact surface between graft and host bone supporting infiltration and ingrowth of blood, growth factors, capillaries and blood vessels. The authors of this article always decorticate and perforate the host bone with a small diameter drill (Ø0.8 – 1.2 mm) when using allograft blocks. 3. Preparation of recipient site and block shaping The prepared allograft block and recipient site should ensure intimate contact without wiggling of the block. To ensure intimate contact with the recipient site, it is sometimes useful to line gaps between block graft and host bone with bone graft particles or autogenous bone. Once stability has been achieved, the block should be fixed to prevent any motion and rotation i.e. with screws (Fig 5). The user can choose from different types and brands of bone screws. To avoid block fracture during fixation a lag screw technique should be applied. The screws should be placed at least 1 mm from block edges and 3 mm from each other to minimize potential stress fracture. Avoid over torque and fracture of the block. Sharp corners or edges of the blocks have to be rounded (i.e. with a diamond bur) minimizing the risk of soft tissue perforations during healing44. After block fixation any gaps between block graft and host bone is filled with remaining crushed pieces of the block or a particulate bone graft. The augmented site should be completely covered with a resorbable barrier membrane to prevent epithelial and connective tissue ingrowth into the integrating new bone. The use of titanium tacks to stabilize the membrane depends on the membrane type as well on the dimensions of

Fig 5 Screw fixed bone block in place.

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the surgical site. In the cases where tacks are necessary they are mostly placed apical on the buccal site allowing easy removal during implant placement. The resorbable membrane should be adaptable, conformable and lie flat on the block. Collagen membranes with resorption times of 8 – 12 weeks are recommended. 4. Flap closure, suturing and interim prosthesis Closure of the surgical site is critical reg. the outcome of the block grafting procedure. Periosteal releasing incisions (as described above.) are mostly necessary to ensure a tension-free closure of the flap. Suturing should be done with 5/0 or 6/0 monofilament utilizing an atraumatic needle with an appropriate technique (continuous or interrupted horizontal mattress sutures, interrupted sutures etc.) and ensure tension-free primary closure. Sutures should be retained in place as long as wound closure is not complete. To prevent wound dehiscence, it is highly recommended to not load the surgical area with prostheses for at least 8 weeks after surgery. After that removable prostheses relined with soft materials can be used with care. For evaluation of healing postsurgery appointments at 1, 2, 4, 6 and 8 weeks are recommended. 5. Implant placement After healing without adverse events (infection, dehiscence etc.) implants can be placed after 5 to 6 months healing time for horizontal augmentations. For vertical augmentations the healing time should be 6 months at least15,44,45. During this time the allograft blocks become integrated and partially remodeled into new bone as shown earlier in histological and histomorphometric investigations25,46-50 ensuring to achieve implant primary stability (Fig 6, 7).

Fig 6 Implant (Tapered Screw Vent 3.7 x 11.5 mm, Zimmer Dental Inc. Carlsbad, CA) placed after six months healing time: No signs of resorption.

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Fig 7 CT scan of the placed implant at the reconstructed site.

Discussion The use of different kind of bone grafts is widely performed for ridge reconstruction. Allograft block grafting becomes more and more focused because allografts are free of many of the limitations associated with autogenous block grafts i.e. limited amount of available bone, no need for intra or extra-oral harvesting,lower patient morbidity. The available literature provide clear evidence that allogeneic block grafts undergo incorporation followed with new bone formation and nearly complete remodeling of the block graft. Nevertheless, a successful result can only be achieved by following the principles of guided bone regeneration. The influence of decortication/perforation on guided bone regeneration has been studied in animal models previously by different researchers51-57. The results of this studies show that decortications may accelerate revascularization and new bone formation during the first weeks of healing58-61 however after healing time of three or four month no advantage of decortications on bone formation has been found51,52,54. In a review article of Greenstein et al. published 2009 the authors concluded that there is no clear evidence about the usefulness of performing decortication to enhance GBR and successful results can be attained without decortications62. Other studies show that graft volume will be better maintained if the recipient site is decorticated and perforated57,63. It might be speculated by the authors of the present article if decortications/perforation has the same impact while using autogenous or allogeneic bone blocks since both materials are strongly different reg. composition and biology. Autogenous bone is claimed to include - depending on the donor site

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-living cells and growth factors which may stimulate and accelerate the healing process. After transplantation to the recipient site the autogenous bone has to be revascularized within the first stages (up to two weeks64) of healing65. During the first days there is no vascularization of the bone block. As a result, possible living cells trapped in the bone block will die as well blood within the block will be clotted provoking an inflammatory reaction and resorptive processes. Early revascularization of autogenous bone grafts has been suggested as an explanation for the improved maintenance of graft volume previously64,65. Therefore for an autogenous bone block early revascularization is mandatory and decortication of the recipient bed should be done. Allogeneic bone blocks (i.e. Puros Allograft) does not contain living cells after processing and inflammatory reactions and resorptive processes initiated by cell death are not likely. Based on this early revascularization supported by decortications might be not strongly necessary when using allogeneic bone blocks. Up to know there is a discussion between surgeons and scientists if membranes are necessary or covering of the block graft with periosteoum is sufficient concerning of minimizing graft resorption. In a systematic review of 14 controlled studies (animal and human) published by Gielkens et al. in 200766 no clear evidence was found that use of a membrane can minimize the resorption of autogenous bone grafts. However, several authors have shown that less bone resorption occurs when barrier membranes are used67-69 reporting up to 7 times greater resorption without a membrane as compared with sites with membrane placement70. On the other side human studies have been published showing no significant differences reg. resorption of periosteoum covered compared to membrane covered intraoral71 and iliac crest bone blocks72. In both studies no periosteal releasing incisions have been prepared to ensure tensionfree closure. In the prospective, randomized study of Antoun et al.70 periosteoum was scored in the control group (no membrane coverage) as well as the test group (membrane coverage) before closing the flap. After six months healing time they found significantly less bone resorption in the membrane group than in the periosteoum group. In the best of our knowledge no human or animal study about the influence of scoring the periosteum on the resorption of autogenous and/or allogeneic bone blocks has been published. Besides this, Weng et al. have shown in a monkey model that periosteum of adult animals which has been completely elevated from the recipient site does not seem

35

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to support new bone formation. It should therefore be regarded as soft connective tissue which possibly invades the grafted area and impacts new bone formation73. The authors of this article always use a resorbable collagen membrane to cover allogeneic bone blocks independently of scoring the periosteoum or not. Published data support this strategy since the determined resorption of collagen membrane covered cancellous and cortico-cancellous block grafts is negligible after healing period of 4 to 7 months15,23,24,44,74,75. The surgeon should choose a membrane with a resorption time up to 3 to 4 months to safely prevent soft tissue ingrowth in the cancellous structure of the block grafts allowing a sufficient bony regeneration. There were some articles published describing implant placement after 4 month of healing time76. Since the revascularization, integration and remodeling of the allograft block depends on different aspects (i.e. block dimensions, patient age and compliance, host bone quality and quantity) the risk of block fracture or dislocation of the block from host bone can be minimized by allowing a longer healing time. Recently Hawthorne et al. have shown in an animal model that integration of an allogeneic bone block needs more time than autogenous bone blocks but finally but types show predictable results after healing time 49. Reg. adverse events the most common problems are soft tissue dehicsences and infections resulting from improper contouring or inappropriate flap closures as well suture techniques15,77. However, long term results of implants placed in allograft reconstructed jaws have shown survival rates between 93 – 95 %15,23,24,78,79. Further studies are needed to clearly state the performance and long term results of allograft block grafting.

Discussion The use of different kind of bone grafts is widely performed for ridge reconstruction. Allograft block grafting becomes more and more focused because allografts are free of many of the limitations associated with autogenous block grafts i.e. limited amount of available bone, no need for intra or extra-oral harvesting,lower patient morbidity. The available literature provide clear evidence that allogeneic block grafts undergo incorporation followed with new bone formation and nearly complete remodeling of the block graft. Nevertheless, a successful result can only be achieved by following the principles of guided bone regeneration. The influence

36

of decortication/perforation on guided bone regeneration has been studied in animal models previously by different researchers51-57. The results of this studies show that decortications may accelerate revascularization and new bone formation during the first weeks of healing58-61 however after healing time of three or four month no advantage of decortications on bone formation has been found51,52,54. In a review article of Greenstein et al. published 2009 the authors concluded that there is no clear evidence about the usefulness of performing decortication to enhance GBR and successful results can be attained without decortications62. Other studies show that graft volume will be better maintained if the recipient site is decorticated and perforated57,63. It might be speculated by the authors of the present article if decortications/perforation has the same impact while using autogenous or allogeneic bone blocks since both materials are strongly different reg. composition and biology. Autogenous bone is claimed to include - depending on the donor site -living cells and growth factors which may stimulate and accelerate the healing process. After transplantation to the recipient site the autogenous bone has to be revascularized within the first stages (up to two weeks 64) of healing65. During the first days there is no vascularization of the bone block. As a result, possible living cells trapped in the bone block will die as well blood within the block will be clotted provoking an inflammatory reaction and resorptive processes. Early revascularization of autogenous bone grafts has been suggested as an explanation for the improved maintenance of graft volume previously64,65. Therefore for an autogenous bone block early revascularization is mandatory and decortication of the recipient bed should be done. Allogeneic bone blocks (i.e. Puros Allograft) does not contain living cells after processing and inflammatory reactions and resorptive processes initiated by cell death are not likely. Based on this early revascularization supported by decortications might be not strongly necessary when using allogeneic bone blocks. Up to know there is a discussion between surgeons and scientists if membranes are necessary or covering of the block graft with periosteoum is sufficient concerning of minimizing graft resorption. In a systematic review of 14 controlled studies (animal and human) published by Gielkens et al. in 200766 no clear evidence was found that use of a membrane can minimize the resorption of autogenous bone grafts. However, several authors have shown that less bone resorption occurs when barrier membranes are used67-69 reporting up to 7 times great-

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er resorption without a membrane as compared with sites with membrane placement70. On the other side human studies have been published showing no significant differences reg. resorption of periosteoum covered compared to membrane covered intraoral71 and iliac crest bone blocks72. In both studies no periosteal releasing incisions have been prepared to ensure tension-free closure. In the prospective, randomized study of Antoun et al.70 periosteoum was scored in the control group (no membrane coverage) as well as the test group (membrane coverage) before closing the flap. After six months healing time they found significantly less bone resorption in the membrane group than in the periosteoum group. In the best of our knowledge no human or animal study about the influence of scoring the periosteum on the resorption of autogenous and/or allogeneic bone blocks has been published. Besides this, Weng et al. have shown in a monkey model that periosteum of adult animals which has been completely elevated from the recipient site does not seem to support new bone formation. It should therefore be regarded as soft connective tissue which possibly invades the grafted area and impacts new bone formation73. The authors of this article always use a resorbable collagen membrane to cover allogeneic bone blocks independently of scoring the periosteoum or not. Published data support this strategy since the determined resorption of collagen membrane covered cancellous and cortico-cancellous block grafts is negligible after healing period of 4 to 7 months15,23,24,44,74,75. The surgeon should choose a membrane with a resorption time up to 3 to 4 months to safely prevent soft tissue ingrowth in the cancellous structure of the block grafts allowing a sufficient bony regeneration. There were some articles published describing implant placement after 4 month of healing time76. Since the revascularization, integration and remodeling of the allograft block depends on different aspects (i.e. block dimensions, patient age and compliance, host bone quality and quantity) the risk of block fracture or dislocation of the block from host bone can be minimized by allowing a longer healing time. Recently Hawthorne et al. have shown in an animal model that integration of an allogeneic bone block needs more time than autogenous bone blocks but finally but types show predictable results after healing time49. Reg. adverse events the most common problems are soft tissue dehicsences and infections resulting from improper contouring or inappropriate flap closures as well suture techniques15,77. However, long term results of implants placed in allograft recon-

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structed jaws have shown survival rates between 93 – 95 %15,23,24,78,79. Further studies are needed to clearly state the performance and long term results of allograft block grafting.

Conclusion Based on the recent literature and experiences of the authors the described surgical technique indicates that allograft block grafting can result in successful implant placement and can serve as an alternative to conventional autogenous bone blocks.

References   1. Aghaloo TL, Moy PK. Which hard tissue augmentation techniques are the most successful in furnishing bony support for implant placement? Int J Oral Maxillofac Implants 2007;22 Suppl:49-70.   2. Wang HL, Carroll MJ. Guided bone regeneration using bone grafts and collagen membranes. Quintessence Int 2001;32:504-515.   3. Cordaro L, Torsello F, Accorsi Ribeiro C, Liberatore M, Mirisola di Torresanto V. Inlay-onlay grafting for three-dimensional reconstruction of the posterior atrophic maxilla with mandibular bone. Int J Oral Maxillofac Surg 2010;39:350-357.   4. Proussaefs P, Lozada J. The use of intraorally harvested autogenous block grafts for vertical alveolar ridge augmentation: a human study. Int J Periodontics Restorative Dent 2005;25:351-363.   5. Schwartz-Arad D, Levin L. Intraoral autogenous block onlay bone grafting for extensive reconstruction of atrophic maxillary alveolar ridges. J Periodontol 2005;76:636-641.   6. Nkenke E, Radespiel-Troger M, Wiltfang J, Schultze-Mosgau S, Winkler G, Neukam FW. Morbidity of harvesting of retromolar bone grafts: a prospective study. Clin Oral Implants Res 2002;13:514-521.   7. Nkenke E, Schultze-Mosgau S, Radespiel-Troger M, Kloss F, Neukam FW. Morbidity of harvesting of chin grafts: a prospective study. Clin Oral Implants Res 2001;12:495-502.   8. Misch CM. Comparison of intraoral donor sites for onlay grafting prior to implant placement. Int J Oral Maxillofac Implants 1997;12:767-776.   9. Raghoebar GM, Meijndert L, Kalk WW, Vissink A. Morbidity of mandibular bone harvesting: a comparative study. Int J Oral Maxillofac Implants 2007;22:359-365. 10. Mertens C, Steveling HG. Use of Synthetic Bone Blocks as an Alternative to Autologous Bone Block Grafts. Implants - international magazine of oral implantology 2009;4. 11. Yamauchi K, Takahashi T, Funaki K, Hamada Y, Yamashita Y. Histological and histomorphometrical comparative study of [beta]-tricalcium phosphate block grafts and periosteal expansion osteogenesis for alveolar bone augmentation. Int J Oral Maxillofac Surg 2010;39:1000-1006. 12. Zecha PJ, Schortinghuis J, van der Wal JE, Nagursky H, van den Broek KC, Sauerbier S, Vissink A, Raghoebar GM. Applicability of equine hydroxyapatite collagen (eHAC) bone blocks for lateral augmentation of the alveolar crest. A histological and histomorphometric analysis in rats. Int J Oral Maxillofac Surg 2011;40:533-542. 13. Schultheiss M, Sarkar M, Arand M, Kramer M, Wilke H-J, Kinzl L, Hartwig E. Solvent-preserved, bovine cancellous bone blocks used for reconstruction of thoracolumbar fractures in minimally invasive spinal surgery—first clinical results. European Spine Journal 2005;14:192-196. 14. Waasdorp J, Reynolds MA. Allogeneic bone onlay grafts for alveolar ridge augmentation: a systematic review. Int J Oral Maxillofac Implants 2010;25:525-531.

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15. Keith JD, Petrungaro P, Leonetti JA, Elwell CW, Zeren KJ, Caputo C, Nikitakis NG, Schopf C, Warner MM. Clinical and histologic evaluation of a mineralized block allograft: Results from the developmental period (2001-2004). Int J Periodont Rest 2006;26:321-327. 16. Orsini G, Stacchi C, Visintini E, Di Iorio D, Putignano A, Breschi L, Di Lenarda R. Clinical and histologic evaluation of fresh frozen human bone grafts for horizontal reconstruction of maxillary alveolar ridges. Int J Periodontics Restorative Dent 2011;31:535-544. 17. Morelli T, Neiva R, Wang HL. Human histology of allogeneic block grafts for alveolar ridge augmentation: case report. Int J Periodont Rest 2009;29:649-656. 18. Bianchini MA, Buttendorf AR, Benfatti CAM, Bez LV, Ferreira CF, de Andrade RF. The Use of Freeze-Dried Bone Allograft as an Alternative to Autogenous Bone Graft in the Atrophic Maxilla: A 3-Year Clinical Follow-up. Int J Periodont Rest 2009;29:643-647. 19. Tudor C, Srour S, Thorwarth M, Stockmann P, Neukam FW, Nkenke E, Schlegel KA, Felszeghy E. Bone regeneration in osseous defects - application of particulated human and bovine materials. Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontology 2008;105:430-436. 20. Maletta JA, Gasser JA, Fonseca RJ, Nelson JA. Comparison of the healing and revascularization of onlayed autologous and lyophilized allogeneic rib grafts to the edentulous maxilla. J Oral Maxillofac Surg 1983;41:487-499. 21. Carinci F, Brunelli G, Zollino I, Franco M, Viscioni A, Rigo L, Guidi R, Strohmenger L. Mandibles Grafted With Fresh-Frozen Bone: An Evaluation of Implant Outcome. Implant Dent 2009;18:86-90. 22. Contar CMM, Sarot JR, da Costa MB, Bordini J, de Lima AAS, Alanis LRA, Trevilatto PC, Machado MAN. Fresh-Frozen Bone Allografts in Maxillary Ridge Augmentation: Histologic Analysis. J Oral Implantol 2011;37:223-231. 23. Nissan J, Ghelfan O, Mardinger O, Calderon S, Chaushu G. Efficacy of Cancellous Block Allograft Augmentation Prior to Implant Placement in the Posterior Atrophic Mandible. Clinical Implant Dentistry and Related Research 2011;13:279-285. 24. Nissan J, Mardinger O, Calderon S, Romanos GE, Chaushu G. Cancellous bone block allografts for the augmentation of the anterior atrophic maxilla. Clinical Implant Dentistry and Related Research 2011;13:104-111. 25. Leonetti JA, Koup R. Localized maxillary ridge augmentation with a block allograft for dental implant placement: case reports. Implant Dent 2003;12:217-226. 26. Schwarz N, Schlag G, Thurnher M, Eschberger J, Zeng L. Decalcified and undecalcified cancellous bone block implants do not heal diaphyseal defects in dogs. Arch Orthop Trauma Surg 1991;111:47-50. 27. Keith JD. Localized ridge augmentation with a block allograft followed by secondary implant placement: A case report. Int J Periodont Rest 2004;24:11-17. 28. Kappe T, Cakir B, Mattes T, Reichel H, Floren M. Infections after bone allograft surgery: a prospective study by a hospital bone bank using frozen femoral heads from living donors. Cell and Tissue Banking 2010;11:253-259. 29. Mellonig JT. Donor selection, testing, and inactivation of the HIV virus in freeze-dried bone allografts. Pract Periodontics Aesthet Dent 1995;7:13-22; quiz 23. 30. Conrad EU, Gretch DR, Obermeyer KR, Moogk MS, Sayers M, Wilson JJ, Strong DM. Transmission of the hepatitis-C virus by tissue transplantation. Journal of Bone and Joint Surgery-American Volume 1995;77:214-224. 31. Holtzclaw D, Toscano N, Eisenlohr L, Callan D. The safety of bone allografts used in dentistry - A review. J Am Dent Assoc 2008;139:1192-1199. 32. Katthagen BD, Pruß A. Transplantation allogenen Knochens. Der Orthopäde 2008;37:764-771. 33. Katthagen BD, Scheffler S, Becker R, Willkomm D, Mayr HO, Pruß A. Gewinnung, Prozessierung und Transplantation allogener muskuloskelettaler Gewebe. Transfusion Medicine and Hemotherapy 2008;35:438-445. 34. Schoepf C. Allograft Safety: The efficacy of the Tutoplast Process. International Magazine of Oral Implantology 2006;1:10-15. 35. Nguyen H, Morgan DA, Forwood MR. Sterilization of allograft bone: effects of gamma irradiation on allograft biology and biomechanics. Cell and Tissue Banking 2007;8:93-105.

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36. Anderson M, Keyak J, Skinner H. Compressive mechanical properties of human cancellous bone after gamma irradiation. Journal of Bone and Joint Surgery-American Volume 1992;74:747-752. 37. Hinton R, Jinnah RH, Johnson C, Warden K, Clarke HJ. A biomechanical analysis of solvent-dehydrated and freeze-dried human fascia lata allografts. A preliminary report. Am J Sports Med 1992;20:607-612. 38. Thull R, Sturm A, Pesch H-J. Mechanische Eigenschaften nativer und präparierter Spongiosa. In: Pesch H-J, Stoess H, Kummer Bs (eds). Proceedings of the Osteologie aktuell VII. Spinger, 1993: 157-163. 39. Marashdeh MQM. Characterization and Development of Optimization Strategy for the Processing of Allogenic and Xenogenic Bone and Pericardium. Universitätsbibliothek der Universität ErlangenNürnberg, 2007. 40. Froum SJ, Wallace SS, Elian N, Cho SC, Tarnow DP. Comparison of mineralized cancellous bone allograft (Puros) and anorganic bovine bone matrix (Bio-Oss) for sinus augmentation: histomorphometry at 26 to 32 weeks after grafting. Int J Periodont Rest 2006;26:543-551. 41. Buser D, Cho JY, Yeo A. Surgical manual of implant dentistry: stepby-step procedures. Quintessence Berlin 42. Pikos MA. Mandibular Block Autografts for Alveolar Ridge Augmentation. Atlas of the Oral and Maxillofacial Surgery Clinics 2005;13:91-107. 43. Kleinheinz J, Buchter A, Kruse-Losler B, Weingart D, Joos U. Incision design in implant dentistry based on vascularization of the mucosa. Clin Oral Implants Res 2005;16:518-523. 44. Wallace S, Gellin R. Clinical evaluation of freeze-dried cancellous block allografts for ridge augmentation and implant placement in the maxilla. Implant Dent 2010;19:272-279. 45. Wallace S, Gellin R. Clinical evaluation of a cancellous block allograft for ridge augmentation and implant placement: a case report. Implant Dent 2008;17:151-158. 46. Minichetti JC, D’Amore JC, Hong AY, Cleveland DB. Human histologic analysis of mineralized bone allograft (Puros) placement before implant surgery. J Oral Implantol 2004;30:74-82. 47. Nissan J, Marilena V, Gross O, Mardinger O, Chaushu G. Histomorphometric analysis following augmentation of the posterior mandible using cancellous bone-block allograft. Journal of Biomedical Materials Research Part A 2011;97A:509-513. 48. Nissan J, Marilena V, Gross O, Mardinger O, Chaushu G. Histomorphometric analysis following augmentation of the anterior atrophic maxilla with cancellous bone block allograft. Int J Oral Maxillofac Implants 2012;27:84-89. 49. Hawthorne AC, Xavier SP, Okamoto R, Salvador SL, Antunes AA, Salata LA. Immunohistochemical, tomographic, and histological study on onlay bone graft remodeling. Part III: allografts. Clin Oral Implants Res 2012:n/a-n/a. 50. Shand JM, Heggie AAC, Holmes AD, Holmes W. Allogeneic bone grafting of calvarial defects: an experimental study in the rabbit. Int J Oral Maxillofac Surg 2002;31:525-531. 51. Lundgren AK, Lundgren D, Hammerle CH, Nyman S, Sennerby L. Influence of decortication of the donor bone on guided bone augmentation. An experimental study in the rabbit skull bone. Clin Oral Implants Res 2000;11:99-106. 52. Slotte C, Lundgren D. Impact of Cortical Perforations of Contiguous Donor Bone in a Guided Bone Augmentation Procedure: An Experimental Study in the Rabbit Skull. Clinical Implant Dentistry and Related Research 2002;4:1-10. 53. Nishimura I, Shimizu Y, Ooya K. Effects of cortical bone perforation on experimental guided bone regeneration. Clin Oral Implants Res 2004;15:293-300. 54. Adeyemo WL, Reuther T, Bloch W, Korkmaz Y, Fischer JH, Zoller JE, Kuebler AC. Influence of host periosteum and recipient bed perforation on the healing of onlay mandibular bone graft: an experimental pilot study in the sheep. Oral Maxillofac Surg 2008;12:19-28. 55. Sebaoun J-D, Kantarci A, Turner JW, Carvalho RS, Van Dyke TE, Ferguson DJ. Modeling of Trabecular Bone and Lamina Dura Following Selective Alveolar Decortication in Rats. J Periodontol 2008;79:1679-1688. 56. Oda T, Kinoshita K, Ueda M. Effects of Cortical Bone Perforation on Periosteal Distraction: An Experimental Study in the Rabbit Mandible. J Oral Maxillofac Surg 2009;67:1478-1485.

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57. Pedrosa WF, Okamoto R, Faria PEP, Arnez MFM, Xavier SP, Salata LA. Immunohistochemical, tomographic and histological study on onlay bone graft remodeling. Part II: calvarial bone. Clin Oral Implants Res 2009;20:1254-1264. 58. Rompen EH, Biewer R, Vanheusden A, Zahedi S, Nusgens B. The influence of cortical perforations and of space filling with peripheral blood on the kinetics of guided bone generation. A comparative histometric study in the rat. Clin Oral Implants Res 1999;10:85-94. 59. Cha JK, Kim CS, Choi SH, Cho KS, Chai JK, Jung UW. The influence of perforating the autogenous block bone and the recipient bed in dogs. Part II: histologic analysis. Clin Oral Implants Res 2012;23:987-992. 60. Seol KY, Kim SG, Kim HK, Moon SY, Kim BO, Ahn JM, Jang HS, Kim HJ, Min JB, Lee BJ, Lim SC. Effects of decortication in the treatment of bone defect around particulate dentin-coated implants: an experimental pilot study. Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontology 2009;108:529-536. 61. Faria PEP, Okamoto R, Bonilha-Neto RM, Xavier SP, Santos AC, Salata LA. Immunohistochemical, tomographic and histological study on onlay iliac grafts remodeling. Clin Oral Implants Res 2008;19:393-401. 62. Greenstein G, Greenstein B, Cavallaro J, Tarnow D. The Role of Bone Decortication in Enhancing the Results of Guided Bone Regeneration: A Literature Review. J Periodontol 2009;80:175-189. 63. Oh KC, Cha JK, Kim CS, Choi SH, Chai JK, Jung UW. The influence of perforating the autogenous block bone and the recipient bed in dogs. Part I: a radiographic analysis. Clin Oral Implants Res 2011;22:1298-1302. 64. Pinholt EM, Solheim E, Talsnes O, Larsen TB, Bang G, Kirkeby OJ. Revascularization of calvarial, mandibular, tibial, and iliac bone grafts in rats. Ann Plast Surg 1994;33:193-197. 65. Kusiak JF, Zins JE, Whitaker LA. The early revascularization of membranous bone. Plastic and Reconstructive Surgery 1985;76:510-516. 66. Gielkens PF, Bos RR, Raghoebar GM, Stegenga B. Is there evidence that barrier membranes prevent bone resorption in autologous bone grafts during the healing period? A systematic review. The International journal of oral & maxillofacial implants 2007;22:390-398. 67. Toscano N, Shumaker N, Holtzclaw D. The Art of Block Grafting: A review of the surgical protocol for reconstruction of alveolar ridge deficiency. The Journal of Implant & Advanced Clinical Dentistry 2010;2:45-66. 68. Kim S-H, Kim D-Y, Kim K-H, Ku Y, Rhyu I-C, Lee Y-M. The efficacy of a double-layer collagen membrane technique for overlaying block grafts in a rabbit calvarium model. Clin Oral Implants Res 2009;20:1124-1132.

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69. Jensen OT, Greer RO, Jr., Johnson L, Kassebaum D. Vertical guided bone-graft augmentation in a new canine mandibular model. Int J Oral Maxillofac Implants 1995;10:335-344. 70. Antoun H, Sitbon JM, Martinez H, Missika P. A prospective randomized study comparing two techniques of bone augmentation: onlay graft alone or associated with a membrane. Clin Oral Implants Res 2001;12:632-639. 71. Verdugo F, D’Addona A, Ponton J. Clinical, Tomographic, and Histological Assessment of Periosteal Guided Bone Regeneration with Cortical Perforations in Advanced Human Critical Size Defects. Clinical Implant Dentistry and Related Research 2012;14:112-120. 72. Heberer S, Ruhe B, Krekeler L, Schink T, Nelson JJ, Nelson K. A prospective randomized split-mouth study comparing iliac onlay grafts in atrophied edentulous patients: covered with periosteum or a bioresorbable membrane. Clin Oral Implants Res 2009;20:319-326. 73. Weng D, Hurzeler MB, Quinones CR, Ohlms A, Caffesse RG. Contribution of the periosteum to bone formation in guided bone regeneration - A study in monkeys. Clin Oral Implants Res 2000;11:546-554. 74. Peleg M, Sawatari Y, Marx RN, Santoro J, Cohen J, Bejarano P, Malinin T. Use of corticocancellous allogeneic bone blocks for augmentation of alveolar bone defects. Int J Oral Maxillofac Implants 2010;25:153-162. 75. Pendarvis WT, Sandifer JB. Localized Ridge Augmentation Using a Block Allograft with Subsequent Implant Placement: A Case Series. Int J Periodont Rest 2008;28:509-516. 76. Kim SG, Park JS, Lim SC. Placement of implant after bone graft using J block allograft. Implant Dent 2010;19:21-28. 77. Chaushu G, Mardinger O, Peleg M, Ghelfan O, Nissan J. Analysis of Complications Following Augmentation With Cancellous Block Allografts. J Periodontol 2010;81:1759-1764. 78. Novell J, Novell-Costa F, Ivorra C, Fariñas O, Munilla A, Martinez C. Five-Year Results of Implants Inserted Into Freeze-Dried Block Allografts. Implant Dent 2012;21:129-135 110.1097/ ID.1090b1013e31824bf31899f. 79. Franco M, Tropina E, De Santis B, Viscioni A, Rigo L, Guidi R, Carinci F. A 2-year follow-up study on standard length implants inserted into alveolar bone sites augmented with homografts. Stomatologija 2008;10:127-132.

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Trabecular Metal™ Dental Implants: Overview of design and developmental research Michael Collins*, Jeff Bassett**, Hai Bo Wen***, Chris Gervais****, Matt Lomicka*****, Savvas Papanicolaou****** Research in implant biomaterials and surface technologies over the past three decades has led to development of a porous tantalum biomaterial with a structure and elasticity similar to trabecular bone. This material has been used extensively in orthopedic reconstructions for over a decade. Recent advancements have led to the development of a new Trabecular Metal Dental Implant (Zimmer Dental Inc., Carlsbad, CA, USA). This article presents an overview of the implant design, and discusses some of the underlying research that led to its development. Keywords: Tantalum, Trabecular Metal, Dental Implant, Biomaterial.

INTRODUCTION Attempts to replace missing teeth with implanted materials have been observed in ancient human remains,1 and documented experimentally and clinically in the dental literature since the 19th century.2,3 Over the past 3 decades, dental implant systems have been commercialized in a variety of materials, including tantalum,2,4,5 vitreous carbon,6-8 single-crystal sapphire,9,10 stainless steel,2,3 titanium,3,11-14 and other substances. The era of modern implant dentistry, however, is primarily built on orthopedic titanium research subsequently adapted for dental implant applications. In 1940, orthopedic surgeons15 first experimented with *  MSBME, MBA,Vice President, Research, Development and Education. ** BS, Director, Engineering. *** PhD, Associate Director, Dental Research and Clinical Affairs. **** BS, Associate Director, Engineering. ***** MS, Senior Design Engineer. ****** MS, Design Engineer. Correspondence: Michael Collins Zimmer Dental 1900 Aston Avenue - Carlsbad, CA 92008 - US E-mail: [email protected]

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the surgical use of titanium and reported its extreme biocompatibility. In the 1950s, other orthopedic surgeons16,17 documented titanium’s superior ability to withstand corrosion and remain relatively inert in the body.18-20 In 1977, orthopedic surgeon Per-Ingvar Brånemark and colleagues11-14 published results of their monumental 10-year dental implant study. The Brånemark team documented11-14 the processes and conditions in which ordered, living bone could form a direct structural and functional connection with a load-carrying titanium dental implant. The researchers11 coined the term “osseointegration” to describe the natural phenomenon first reported more than three decades earlier by their predecessors.15-17 In the three decades since the seminal Brånemark study11 was published, continuing dental and orthopedic research has focused on various techniques for enhancing bone apposition to implanted titanium surfaces. Despite differences in anatomical locations and bone structures, a variety of surface modification techniques developed in orthopedics have since been successfully adapted for dental implant use. Among these are hydroxylapatite (HA), titanium plasma spray (TPS), and porous surface coatings, such as porous bead surfaces and cancellous-structured titanium (CSTi™) Coating.

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Fig 1  SEM view of trabecular bone (left) and Trabecular Metal Material (right).

Fig 2  SEM cross-section of Trabecular Metal Material struts shows the (a) tantalum coating over (b) the vitreous carbon skeleton.

Trabecular Metal Material (Zimmer Dental Inc., Carlsbad, CA, USA) is a porous biomaterial with a structure and stiffness similar to trabecular bone (Fig. 1).21-26 It is fabricated by coating a vitreous carbon skeleton with tantalum (Fig. 2) through a proprietary chemical vapor deposition coating process. The tantalum exhibits a crystallographic growth pattern26,27 on the vitreous carbon surface of the interconnecting struts23,27-31 (Fig. 1) that form the material. Trabecular Metal Technology significantly differs from sintered bead surfaces, titanium plasma-sprayed surfaces, titanium fiber mesh and titanium foam in the high degree of its interconnected porosity (up to 80%) and the regularity of its pore size and shape.23,27,28,30,31 In contrast to conventional bone-to-implant contact achieved by non-porous surfaces, Trabecular Metal Technology’s geometrical network of interconnected pores is designed for biological ingrowth through the pores.20,24-27,30-32 This Trabecular Metal Material has been used extensively in orthopedic reconstructions for more than a decade.23-25,28,31,33,34 The present article will present an overview of a new Trabecular Metal Dental Implant and its developmental research.

Preliminary experiments with Trabecular Metal Technology as a biomaterial Trabecular Metal Technology was originally commercialized as Hedrocel® Material, and envisioned as a 3-dimensional bone augmentation material. Commencing in the early 1990s, a series of in vivo canine evalua-

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tions30,35-37 in the canine model and mechanical testing38 experimentally evaluated Trabecular Metal Material’s 3-dimensional, open-cell structure as a potential implant for cancellous bone ingrowth and support of a dental implant in the alveolar ridge. National Institutes of Health Research Grant (DE09781) Under a research grant from the National Institutes of Health, Kaplan et al.30,35-37 created 18 mm, fullthickness mandibular resections from the right hemimandibles of 6 dogs. A Trabecular Metal Implant was placed in the site and stabilized with a 10-hole reconstruction plate.30,35-37 In the left (opposite) hemi- mandibles, a 17 mm, full-thickness resection was made and then augmented with the bone resected from the right side of the jaw, and stabilized with a 10-hole reconstruction plate.30,35-37 Animals were subjected to daily examination and monthly ventrodorsal radiographs for a period of 6 months to assess healing of the defect sites.30,35-37 Reconstruction plates were removed after 3 months in animals that exhibited mandibular stability in radiographic and physical examinations.30,35-37 Animals that did not demonstrate stability after 3 months were allowed to continue healing and monthly evaluations until stability was confirmed and the plate could be removed.30,35-37 After 6 months, all dogs were sacrificed and the entire mandible was harvested from each animal.30,35-37 Any remaining compression plates were removed from the dogs at the time of sacrifice.30,35-37 Each mandible was sectioned in left (control group) and right (test group) halves.30,35-37

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Fig 3 Mineralized bone ingrowth into porous Trabecular Metal Material (seen as black in the photograph).37 Osteoid matrix conversion to mineralized bone is shown37 (MIBS stain).

Mandible halves were then sectioned and prepared for histologic analysis.30,35-37 A total of 6 mandibles were obtained.30,35-37 In 2 of these, the test implant had fallen out secondary to resorption of the adjacent bone caused by infection.30,35-37 In all surviving samples, the Trabecular Metal Material side was compared with the contralateral control side.30,35-37 All 4 surviving samples had osteoid crossing through the Trabecular Metal Implant, and 3 out of 4 samples had mineralized bone in the center of the material (Fig. 3).30,35-37 One sample had mineralized bone at the edges, but the center was not yet mineralized (Figgs 4 and 5).30,35-37 The majority of the mineralization appeared at the edges of the (osteotomy) cut.30,35-37 There seemed to be more bone forming at the caudal, superior and the lingual aspects of the implants as opposed to the cranial, inferior and buccal sides.30,35-37 Most of the new bone was woven (Fig. 4), however small foci of lamellar bone were seen mostly at the edges of the implant bone interface.30,35-37 Marrow elements were not seen in any sample.36 Cellular elements (osteoblasts) were identified in the woven bone in the implant; however, these were quantitatively more prevalent at the edges.30,35-37 Control samples exhibited good evidence of union in all cases, including the cases that were infected.30,35-37 In comparison to the control cases, the 4 surviving test samples exhibited greater new bone formation in 1 case, less new bone formation in 1 case, and more area of bone formation in 2 cases, but the degree of mineralization was slightly less than that of the control samples.30,35-37 The researchers30,35-37 concluded that Trabecular Metal Technology and autogenous bone were equally success-

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Fig 4 Woven bone ingrowth into Trabecular Metal Material pores37 (trichrome stain, semi-polarized light).

Fig 5  Lamellar bone formation inside porous Trabecular Metal Material.37 According to the researchers, “the maturation of woven bone into lamellar bone is indicative of normal bone and permanency”37 (trichrome stain, semipolarized light).

ful in treating mandibular discontinuity defects. Bone grew into Trabecular Metal Material, mineralized and developed cellular components.30,35-37 United States Patent No. 5,282,861 Issued in 1994 The inventor of United States Patent No. 5,282,861 was also involved in research conducted under the National Institutes of Health Research Grant (DE09781-03) cited above.35 This patent stated that Trabecular Metal Technology could be potentially used for “alveolar ridge augmentation, periodontics, and orthognathic reconstruction,” and that it was “useful in orthopedic applications as well.” Although Trabecular Metal Technology’s actual

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commercialization has been strictly limited to orthopedic applications to date, the 1994 patent (U.S. 5,282,861) further stated that the “present invention may also be used for tooth replacement because of the ability to induce tissue and bone growth even in the face of mildly infectious conditions. For example, an artificial tooth can be joined to an open cell tantalum stem and positioned in an appropriately sized hole in the jaw. The gum is allowed to rest against the artificial tooth and some of the stem to form a seal.” While this proposed dental implant design was never developed with Trabecular Metal Material a similar design made with titanium fiber mesh had been previously launched during the 1970s, but the fibro-osseous interface that it developed limited its success.39-46 Mechanical integrity between Trabecular Metal Material and a single-tooth implant Dillion et al.38 conducted a mechanical experiment to determine the ability of a 3-dimensional Trabecular Metal Material bone graft to support an implant-supported, single-tooth restoration. A 3.7 mm-diameter threaded titanium implant (Screw- Vent® Implant, Zimmer Dental Inc.) was placed in a 10 x 20 x 25 mm Trabecular Metal Material porous tantalum block, which was currently under investigation for use as a bone substitute for large segmental defects.38 The system was evaluated in single-cycle and fatigue in axial compression and cantilever bending. Compression samples were loaded at 25N/sec in air to a maximum of 300N, and bending samples were loaded at 25N/sec in air to failure.38 Fatigue samples were tested in Ringers at 37ºC at 5Hz to 2.5 x 106 cycles.38 Compressive fatigue failure was defined as 0.03 mm of permanent deformation.38 Results showed a mean single-cycle bending strength of 1.04 ± 0.13kN. mm and a mean displacement of 2.47 ± 0.61 mm using a lever arm of 7.5 mm.38 Axial compression tests showed a mean displacement of 0.17 ± 0.01 mm at the maximum 300N load and the average load value at which the sample began to yield was 0.07kN (± .028kN).38 A cantilever bending S/N curve was generated from 80% of yield to run-out at 2.5 x 106 cycles.38 No failure of the Trabecular Metal Material or at the interface was detected.38 All samples failed due to deformation of the abutment screw.38 Axial compressive fatigue was performed to a maximum load of 600N, which was approximately four times normal biting force with no failure.38 Both

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single- cycle and fatigue tests indicated that the implant/Trabecular Metal Material system was able to withstand loads that were significantly greater than those found in vivo.38 Failure of the system occurred in the screw attaching the abutment rather than at the implant/Trabecular Metal Material interface or within the Trabecular Metal Material itself.38 Mechanical feasibility study on the potential use of Trabecular Metal Technology as a dental implant material (ZRR-ZD-00011-07) Cylindrical and hexagonal blocks of Trabecular Metal Material were evaluated for push-in/push-out force, removal torque, and static compression evaluations in a polyether polyurethane surrogate bone material to determine how the material might function during placement into bone, and how it might withstand direct loading. Large-diameter (6.0 mm) Trabecular Metal Material blocks showed good initial stability and were strong enough to resist compressive loading forces that exceeded those documented for the oral environment. Smaller diameter (3.7, 3.0 mm) Trabecular Metal Material blocks would benefit from an anti-rotational feature, such as external threads, to improve initial stability and internal reinforcement to resist compressive forces in the oral environment. For example, an implant made of both titanium and Trabecular Metal Material would be significantly stronger than solid Trabecular Metal Material blocks alone. Results from these experiments indicate that a combination of Trabecular Metal Material and titanium will provide acceptable mechanical characteristics for a dental implant.

Development of Trabecular Metal Technology as a dental implant The implant is a tapered, multi-threaded, endosseous design similar to its predicate, the Tapered ScrewVent® Implant (Zimmer Dental Inc.), but modified with a Trabecular Metal Material midsection (Fig. 6). The coronal, apical and internal implant structures are made of titanium alloy (Ti-6Al-4V grade 5) with a microtextured surface created by grit-blasting with hydroxylapatite (MTX® Surface). The coronal section features cervical micro-grooves and Zimmer Dental’s internal hex, friction- fit connection, and the apical section features selftapping threads. In the midsection of the implant, the Trabecular Metal Material is made of tantalum (98%) over a vitreous carbon substrate (2%) (Fig. 2).

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of its internal vitreous carbon core) (Fig. 2) might have in the osseous environment. Long-term use as a dental implant material in humans,6-8 and short-64,65 and long-term66 animal studies have demonstrated that vitreous carbon is well-tolerated in the oral environment.6 A five-year systemic, toxicological, carcinogenic study in dogs reported that vitreous carbon implants exhibited no systemic responses in the major organs, tissues, blood or urine, and no evidence of inflammatory response or foreign body reactions in the adjacent tissues.6,66 Large-scale hard- and soft-tissue ingrowth into the macroscopic grooves and other surface architecture of vitreous carbon has been extensively documented.6,67,68

Fig 6 Trabecular Metal Dental Implant.

Tantalum This highly biocompatible47-49 metal has been widely used for over half a century in implanted medical devices for humans: dental implants,2,4-5 orthopedic implants,24-26,29,32-34,49-50 surgical ligation clips,47,51 plates, nets and wires used in neurosurgery, cranioplasty, and oral and maxillofacial reconstructions,47,52-56 electrodes for pacemakers,47,57 and many other clinical applications.47,58-59 It has been reported that tantalum does not elicit the cytotoxicity levels associated with some other metals, such as nickel, cobalt and chromium,47,60 and that it exhibits strong resistance to oxidation, corrosion and concomitant ion production.47,41,60-63 Tantalum was initially Brånemark’s13 biomaterial of choice for his early bone growth research. The high cost of tantalum, however, made titanium a more feasible material at the time. Vitreous carbon One early clinical concern in the development of a Trabecular Metal Implant was the effect that exposure

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Mechanical evaluation of 4.7mm-diameter Trabecular Metal Dental Implants (ZRR-ZD-00065-00) The purpose of this experiment was to determine if Trabecular Metal Implants would exhibit an adequate fatigue endurance limit that was equal to or greater than 90 lbs (400N), when subjected to cyclic compressive loading. This strength limitation was based on expected bite force ranges reported in the molar region.69 Other important data collected for investigative purposes included ultimate strength during static compression loading and failure modes under static and fatigue loading. Evaluations were performed with Trabecular Metal Dental Implants, 4.7 mm in diameter, in accordance with corporate requirements (ZRP-ZD-00065-00 and TP-307, Zimmer Dental Inc.), good manufacturing practices, and international standards.70 The 4.7 mm diameter Trabecular Metal Implants had an endurance limit of 100 lbs (445N); therefore, it was concluded that both the 4.7mm and 6.0 mm diameter Trabecular Metal Implants could withstand the forces anticipated in the molar region. Abrasion evaluations of dental implants with porous surfaces (ZRM-ZD-00028-00) This experiment was conducted to evaluate whether the friction caused by implant placement into an osteotomy was capable of damaging porous implant surfaces. Implants with two different porous surfaces were evaluated: Trabecular Metal Dental Implants and CancellousStructured Titanium (CSTi) dental implants. Test samples were microscopically examined at various magnifications, and compared before and after placement into two substrates: • a synthetic surrogate bone material made of rigid, polyether polyurethane with a fine, closed-cell structure (density = 0.32g/cm3; 20 lb/ft3) (Last-A-Foam®,

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General Plastics Manufacturing Co., Tacoma, WA) (bone foam) and bovine condyle. Abrasion leading to subsequent release of metal debris from the implant surfaces was not expected because of differences in shear strengths between porous metal implants and bone. In this study, the Trabecular Metal Material and CSTi dental implants showed no evidence • of abrasion or subsequent release of metal debris into the osteotomy. This was identified under 24X magnification, and was more evident under 65X and 137X magnification levels, where porous sections oriented both parallel and perpendicular to the long axis of the implants showed no deformation after implant placement. Insertion torque analysis of Zimmer Trabecular Metal Dental Implants in simulated dense bone (ZRR-ZD-00060-00 Add 1, ZRM-ZD-00034-00, ZRM-ZD-00035-00) Implant insertion torque values for Trabecular Metal Technology test implants and titanium control implants (Tapered Screw-Vent Implant, Zimmer Dental Inc.; NobelReplace® and NobelActive® Implants, Nobel Biocare, Yorba Linda, CA; SLActive® Bone Level Implant, Straumann, Basel, Switzerland) were evaluated in bone foam. The composition of the bone foam consisted of a dense outer layer (50 lb/ft3) analogous to cortical bone, and a solid, rigid foam core (30 lb/ft3) analogous to trabecular bone. This experiment was conducted to determine if the insertion torque required to place the Trabecular Metal Implant in simulated dense bone was comparable to that of the control implants, which were selected because of their high documented success rates under delayed and immediate loading conditions.71-74 Con-

trol implant average insertion torque values were 119.9 Ncm for the Tapered Screw-Vent 4.7 x 13 mm implant, 93.0 Ncm for the NobelActive 5.0 x 13 mm implant, 89.5 Ncm for the NobelReplace 5.0 x 13mm implant, and 60.5 Ncm for the Straumann Bone Level 4.8 x 12mm implant (Chart 1). Acceptance criteria for this experiment required that the average insertion torque value for Trabecular Metal Implants was between the maximum and minimum torque values exhibited by the control implants. The average insertion torque value of the Trabecular Metal test implants was measured at 104.1 Ncm for 4.7 x 1mm implants (Chart 1). Differences between the test and control implants were statistically significant. Trabecular Metal Dental Implants exhibited insertion torque values within the range exhibited by the commercially available control implants. Numerous studies73-77 have used insertion torque values as stability guidelines for determining whether a dental implant can sustain immediate loading, although there is no clinical consensus on what should constitute a minimum insertion torque level. In general, however, many clinicians73-77 have selected an approximate insertion torque value of 35Ncm or greater as a determining guideline for immediate loading. The average insertion torque values of Trabecular Metal test implants in this study significantly exceeded this threshold (Chart 1). Press-fit analysis of Trabecular Metal Dental Implants (ZRR-ZD-00064-00) As compared to conventionally threaded implants, Trabecular Metal Implants have fewer external threads for primary stabilization, and a porous surface that forms a frictional interface with bone. This experiment evalu-

Chart 1 Insertion torque results* (Ncm). Average Insertion Torque (Ncm)

119.9 104.1

93.0

89.5

Data on file with Zimmer Dental Inc.

60.5

Tapered Screw-Vent Implant 4.7 x 13 mm

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*Average insertion torque in 50/30 bone foam block simulating a dense bone ZRM ZD 00034-00 ZRM ZD 00035-00 ZRR ZD 00060-00 addendum 1

Trabecular Metal Implant 4.7 x 13 mm

NobelActive™ Implant 5.0 x 13 mm

NobelActive™ Implant 5.0 x 13 mm

Straumann® Bone Level Implant 4.8 x 12 mm

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ated the effect of torsional forces on the structural integrity of Trabecular Metal Dental Implants during and after placement in bone. Previous corporate experiments (ZRR-ZD-00060-00) assessed the amount of torque required to place solid Trabecular Metal Material cylinders into bone, and the result frictional placement had on the structural integrity of the material. Results provided baseline data for comparing results obtained when Trabecular Metal Material is incorporated into a threaded implant design. The amount of torque required to compromise the structural integrity of a Trabecular Metal Dental Implant was found to be significantly greater than the amount of torque actually placed on the Trabecular Metal Material itself during implant insertion into bone. Furthermore, a fully integrated implant was found to withstand a rotational force of greater than 355Ncm, which is more than 3-times greater than the anticipated worst- case torsional forces on molars during immediate occlusal loading (110Ncm, per Engineering Analysis, Lab notebook ZDI-269 pp. 28-31). These findings suggest that the Trabecular Metal Material region of the dental implant will not be structurally compromised by torsional forces during placement or immediate loading. Trabecular Metal Dental Implant placement utilizing soft bone and dense bone surgical protocols (ZRR-ZD-00076-00) Implant placement in bone with moderate to high density (types 1 to 3)78 utilizes a final step-drill that prepares a narrower diameter in the apical region of the osteotomy. This technique enables approximately onethird of a tapered implant design to enter the osteotomy before the self-tapping implant threads engage the walls of the receptor site, which may facilitate implant placement in sites with limited vertical access.79 In low-density (type 4)78 bone, final osteotomy preparation is performed with a straight drill that is 0.2 to 0.3 mm smaller than the apical end of a tapered implant, depending on the implant diameter.79 This soft-bone surgical technique is designed to enable the tapered, apical end of an implant to laterally engage the osteotomy walls and gradually compress the surrounding bone to a maximum of 0.6 or 0.7 mm at the crest of the ridge, depending on the implant diameter.79 When the diameter of an osteotomy is a minimum of 100 µm smaller than that of the implant, force-fitting stresses generated during placement have been reported to increase placement torque and implant stability, as compared to implants not placed into smaller diameter osteotomies in low-density bone.79-81 The present experiment was primarily designed to determine if Trabecular Metal Dental Implants could be

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successfully placed in a surrogate soft bone substrate utilizing a soft bone surgical protocol. A second part to this experiment evaluated whether Trabecular Metal Dental Implants could also be placed into dense bone when a soft bone protocol was used. In this case, a successful test was classified as either full placement with a soft bone protocol, or subsequent dense bone protocol, if needed. Experiments showed that Trabecular Metal Implants could be optimally placed if the soft bone surgical protocol was used in soft bone, and the dense bone surgical protocol was used in all other bone densities. Material analysis of Trabecular Metal Dental Implants following exposure to surface cleaning solutions (ZRR-ZD-00054-00) This experiment evaluated the effect of cleaning materials used to remove hydroxylapatite residue following secondary grit-blasting. The contact materials consisted of 5% hydrochloride (HCl), distilled water, acetone, isopropyl alcohol (IPA), and sustained heat on Trabecular Metal Material cylinders. The impact of the contact materials on Trabecular Metal Material was analyzed by mechanical/chemical methods. Results of the analysis indicated that the Trabecular Metal Material cylinders did not suffer adverse effects from the production cleaning methods used in this experiment. Evaluation of Trabecular Metal Dental Implants in the canine model In 2009, researchers82 from The Ohio State University and Zimmer Dental collaborated on the first in vivo study of a Trabecular Metal Dental Implant design. The objectives of the study were to investigate whether Trabecular Metal Material applied to a dental implant would osseointegrate.82 A total of 24 experimental Trabecular Metal Implants were placed in mandibles of 8 dogs (3 implants per dog).82 Additionally 24 control implants (Tapered Screw-Vent Implant, Zimmer Dental Inc.) were placed in the mandibles of the same 8 dogs (3 implants per dog).82 Two (2) animals each were euthanized at2,4,8 and 12 weeks after implantation.82 Calcein was injected prior to necropsy to label newly mineralizing bone tissue.82 Two histological sections from each implant were prepared: one section was used to assess the calceinlabeled tissue and the other was stained by Goldner’s Trichrome to assess osteoid and matured bone.82 Effects of healing time on the histomorphometric analysis measurements were statistically analyzed.82 Histomorphometric analyses of bone in Trabecular Metal Material pores indicated rapid bone fill and re-

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modeling: 1) the highest amount of newly mineralizing tissue was observed at week 2 (36.08%) and significantly lower at later weeks (17.69%, 22.40% and 19.95% respectively, p < 0.05) and 2) osteoid was highest at week 2 (63.53%) and significantly lower at weeks 8 and 12 (35.97% and 41.94%, respectively, p < 0.05).82 Matured bone significantly increased during the same time intervals (3.32%, 9.01% and 18.69% at 2, 8 and 12 weeks, respectively, p < 0.05).82 Active bone formation into the porous surface of Trabecular Metal Implants observed at the early healing stage supports its potential use in dental implant applications.82 Unlike the experimental titanium fiber mesh implants previously cited,39-46 the Trabecular Metal Implants in the present study did not exhibit fibrous tissue anywhere along the bone-implant interface or inside the Trabecular Metal Material pores. At all time periods, average bone-to-implant contact (BIC) on the titanium alloy (i.e. non-Trabecular Metal Material) portions of the implants exceeded 70%. New bone formation inside Trabecular Metal Material pores was evident at 2 weeks and bone ingrowth across the full thickness of the porous surface was observed at 4 weeks.82

Discussion Early development and evaluations of Trabecular Metal Dental Implants have demonstrated their ability to adequately meet the biomechanical demands encountered in the dental environment and to biologically integrate in the canine model. How the material will function in human dental patients, especially when immediately loaded, will be the next research phase of Trabecular Metal Dental Implants. In 2010, Zimmer Dental established a prospective pilot clinical study of Trabecular Metal Dental Implants, and a multi-national Trabecular Metal Implant Longitudinal Data Collection Program that will continue to monitor and gather data on the implants over the coming years. New data will be published as it is accrued.

References   1. Ring ME. A thousand years of dental implants: a definitive history — part 1. Compend Contin Educ Dent. 1995;16:1060,1062,1064 passim.   2. Ring ME. A thousand years of dental implants: a definitive history — part 2. Compend Contin Educ Dent. 1995;16:1132,1134,1136 passim.   3. Greenfield, EJ. Implantation of artificial crown and bridge abutments. Dental Cosmos. 1913;55:364-369.

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  4. Linkow LI, Rinaldi AW. Evolution of the Vent-Plant osseointegrated compatible implant system. Int J Oral Maxillofac Implants. 1988;3:109-122.   5. Grundschober F, Kellner G, Eschberger J, Plenk H Jr. Long term osseous anchorage of endosseous dental implants made of tantalum and titanium. In: Winter GB, Gibbons DF, Plenk H Jr (Eds.). Biomaterials 1980. Chichester: John Wiley & Sons, 1982:365-370.   6. Grenoble DE, Voss R. Analysis of five years of study of vitreous carbon endosseous implants in humans. Oral Implantol. 1977;6:509-525.   7. Grenoble DE, Voss R. Case studies with carbon endosseous implants. Alpha Omegan. 1975;68:16-19.   8. Lemons JE. Biomaterials science protocols for clinical investigations on porous alumina ceramic and vitreous carbon implant. J Biomed Mater Res Symposium. 1975;6:9-16.   9. Kawahara H, Hirabayashi M, Shikita T. Single crystal alumina for dental implants and bone screws. J Biomed Mater Res. 1980;14:597-605. 10. Arvidson K, Fartash B, Moberg L-E, Grafström R, Ericsson I. In vitro and in vivo experimental studies on single crystal sapphire dental implants. Clin Oral Impl Res. 1991;2:47-55. 11. Brånemark PI, Hansson BO, Adell R, Breine U, Lindström J, Hallén O, Öhman A. Osseointegrated implants in the treatment of the edentulous jaw. Experience from a 10-year period. Scand J Plast Reconstr Surg. 1977;111 (Suppl 16):1-132. 12. Brånemark PI. Osseointegration and its experimental background. J Prosthet Dent. 1983;50:399-410. 13. Brånemark PI. Introduction to osseointegration. In Brånemark PI, Zarb GA, and Albrektsson T (Eds.): Tissue-Integrated Prostheses. Osseointegration in Clinical Dentistry. Chicago, IL: Quintessence Publishing Co, Inc, 1985:11-76. 14. Brånemark PI. Tooth replacement by oral endoprostheses: Clinical aspects. J Dent Educat. 1988;52:821-823. 15. Bothe RT, Beaton LE, Davenport HA. Reaction of bone to multiple metallic implants. Surg, Gynecology, and Obstetrics. 1940;71:598-602. 16. Leventhal GS. Titanium, a metal for surgery. J Bone Joint Surg. 1951;33(A):473-474. 17. Clarke EGC, Hickman J. An investigation into the correlation between the electric and potential of metals and their behaviour in biological fluids. J Bone Joint Surg. 1953;35(B):467-473. 18. Brunski JB. Biomaterials and biomechanics in dental implant design. Int J Oral Maxillofac Implants. 1988;3(2):85-97. 19. Clark AE. Principles of tissue implant material interactions. In Caswell CW, Clark Jr. AE (Eds.): Dental Implant Prosthodontics. Philadelphia: JB Lippincott Co, 1991:317-322. 20. Williams DF. Titanium as a metal for implantation. Part 1: Physical properties. J Med Engineer Tech. 1977;7:195-198, 202. 21. Wigfield C, Robertson J, Gill S, Nelson R. Clinical experience with porous tantalum cervical interbody implants in a prospective randomized controlled trial. Br J Neurosurg. 2003;17:418-425. 22. Hacking SA, Bobyn JD, Toh KK, Tanzer M, Krygier JJ. Fibrous tissue ingrowth and attachment to porous tantalum. J Biomed Mater Res. 2000;52:631-638. 23. Shimko DA, Shimko VF, Sander EA, Dickson KF, Nauman EA. Effect of porosity on the fluid flow characteristics and mechanical properties of tantalum scaffolds. J Biomed Mater Res. Part B: Appl Biomater. 2005;73B:315-325. 24. Nasser S, Poggie RA. Revision and salvage patellar arthroplasty using a porous tantalum implant. J Arthroplasty. 2004;19:562-572. 25. Tsao AK, Roberson JR, Christie MJ, Dore DD, Heck DA, Robertson DD, Poggie RA. Biomechanical and clinical evaluations of a porous tantalum implant for the treatment of early-stage osteonecrosis. J Bone Joint Surg. 2005;87-A(Suppl 2):22-27. 26. Unger AS, Lewis RJ, Gruen T. Evaluation of a porous tantalum uncemented acetabular cup in revision total hip arthroplasty. Clinical and radiological results of 60 hips. J Arthroplasty. 2005;20:1002-1009. 27. Zardiackas LD, Parsell DE, Dillion LD, Mitchell DW, Nunnery LA, Poggie R. Structure, metallurgy, and mechanical properties of a porous tantalum foam. J Biomed Mater Res (Appl Biomater). 2001;58:180-187. 28. Bobyn JD, Stackpool GJ, Hacking SA, Tanser M, Krygier JJ. Characteristics of bone ingrowth and interface mechanics of a new porous tantalum biomaterial. J Bone Joint Surg (Br). 1999;81-B:907-914. 29. Bobyn JD. UHMWPE: the good, bad & ugly. Fixation and bearing surfaces for the next millennium. Orthop. 1999;22:810-812.

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30. Khurana JS, Fordyce H, Sidebotham C, Smith G. Bone growth in a novel osteoconductive material for artificial bone replacement. Submitted to the 45th Annual Meeting of the Orthopaedic Research Society, Anaheim, CA, USA, February 1-4, 1999. 31. Bobyn JD, Toh KK, Hacking A, Tanzer M, Krygier JJ. Tissue response to porous tantalum acetabular cups. J Arthroplasty. 1999;14:347-354. 32. Bobyn JD, Poggie RA, Krygier JJ, Lewallen DF, Hanssen AD, Lewis RJ, Unger AS, O’Keefe TJ, Christie MH, Nasser S, Wood JE, Stulberg SD, Tanzer M. A structural porous tantalum biomaterial for adult reconstruction. J Bone Joint Surg. 2004;86-A(Suppl 2):123-129. 33. Gruen TA, Poggie RA, Lewallen DF, Hanssen Ad, Lewis RJ, O’Keefe TJ, Stulberg SD, Suthreland CJ. Radiographic evaluation of a monoblock acetabular component. J Arthroplasty. 2005;20:369-378. 34. Nehme A, Lewallen DF, Hanssen AD. Modular porous metal augments for treatment of severe acetabular bone loss during revision hip arthroplasty. Clin Orthop Relat Res. 2004;429:201-208. 35. Kaplan RB, Smith GK, Khurana JS, Puerto DA, LaFond E, Sidebotham C. Mandibular reconstruction with a porous tantalum implant in a canine model. National Institutes of Health, Grant No. DE09781-03, 1997. 36. Smith GK, Fordyce HH, Puerto DA, Khurana J, Cohen R. Bone ingrowth and remodeling associated with Hedrocel canine mandibular reconstruction implant. Submitted to the 46th Annual Meeting of the Orthopaedic Research Society, Orlando, FL, USA, March 12-15, 2000. 37. Smith G, Poggie R, Fordyce H, Hosalkar H, Khurana J, Scherbel U, Schultz P, Sidepotham C, Cohen R. Characterization of bone ingrowth and remodeling in a canine mandibular defect model. Submitted to the 47th Annual Meeting of the Orthopaedic Research Society, San Francisco, CA, USA, February 25-28, 2001. 38. Dillion LD, Zardiackas LD. Mechanical integrity between Hedrocel and a single tooth implant. Presented at the Annual Research Meeting of the American Association for Dental Research, Chicago, Illinois, USA, March 2001. 39. Weiss MB. Development of an endosseous dental implant (I). Quintessence Int Dent Dig. 1977;8:87-91. 40. Weiss MB, Rostoker W. Development of an endosseous dental implant (II). Quintessence Int Dent Dig. 1977;8:107-112. 41. Weiss MB, Rostoker W. Development of an endosseous dental implant (III). Quintessence Int Dent Dig. 1977;8:77-84. 42. Weiss MB, Rostoker W. Development of an endosseous dental implant (IV). Quintessence Int Dent Dig. 1977;8:75-80. 43. Weiss MB, Rostoker W. Development of a new endosseous dental implant. Part I: animal studies. J Prosthet Dent. 1981;46:646-651. 44. Weiss MB, Rostoker W. Development of a new endosseous dental implant. Part II: human studies. J Prosthet Dent. 1982;47:633-645. 45. Weiss MB, Gutman D, Rostoker W. A new fiber metal dental implant. Compend Contin Educ Dent. 1984;5:383-388. 46. Weiss MB. Titanium fiber-mesh metal implant. J Oral Implantol. 1986;12:498-507. 47. Black J. Biological performance of tantalum. Clin Mater. 1994;16:167173. 48. American Society for Testing and Materials. Standard specification for unalloyed tantalum for surgical implant applications (ASTM F 560-98). In: Annual Book of ASTM Standards, ASTM, 1998;13.01:63-65. 49. Koutsostathis SD, Tsakotos GA, Papakostas I, Macheras GA. Biological process at bone-porous tantalum interface. A review article. J Orthopaedics. 2009;6(4)e3. Available online at http://www.jortho. org/2009/6/4/e3. Accessed 31 March 2010. 50. Plenk H Jr, Pfluger G, Schider S, Bohler N, Grundschober F. The current status of uncemented tantalum and niobium femoral endoprostheses. In: Morscher E (Ed.): The Cementless Fixation of Hip Endoprostheses. Berlin: Springer-Verlag, 1984:174-177. 51. Brown MA, Carden JA, Coleman RE, McKinney R Jr., Spicer LD. Magnetic field effects on surgical ligation clips. Magn Reson Imaging. 1987;5:443-453. 52. Pudenz RH. The repair of cranial defects with tantalum: an experimental study. J Amer Med Assoc. 1943;121:478-481. 53. Echols DH, Colclough JA. Cranioplasty with tantalum plate. Report of eight cases. Surgery. A Monthly Journal Devoted to the Art and Science of Surgery. 1945;17:304-414. 54. Bellinger DH. Preliminary report on the use of tantalum maxillofacial and oral surgery. J Oral Surg. 1947;5:108-122. 55. Spurling RG. The use of tantalum wire and foil in the repair of peripheral nerves. Surg Clin North Am. 1943;23:1491-1504.

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56. McFadden JT. Tissue reactions to standard neurosurgical metallic implants. J Neurosurg. 1972;36:598-603. 57. Johnson PF, Bernstein JJ, Hunter G, Dawson WW, Hench LL. An in vitro and in vivo analysis of anodized tantalum capacitive electrodes: corrosion response, physiology and histology. J Biomed Mater Res. 1977;11:637-656. 58. McClung EJ, Chipps JE. Tantalum foil used in closing antro-oral fistulas. US Armed Forces Med J. 1951;2:1183-1186. 59. Aronson AS, Jonsson N, Alberius P. Tantalum markers in radiography: an assessment of tissue reactions. Skeletal Radiol. 1985;14:207-211. 60. Burke GL. The corrosion of metals in tissues and an introduction to tantalum. Can Med Assoc J. 1940;43:125-128. 61. Kokubo T. Metallic materials stimulating bone formation. Med J Malaysia. 2004;59(Suppl B):91-92. 62. Findlay DM, Welldon K, Atkins GJ, Howie DW, Zannettino AC, Bobyn D. The proliferation and phenotypic expression of human osteoblasts on tantalum metal. Biomaterials. 2004;25:2215-2227. 63. Welldon KJ, Atkins GJ,Howie DW, Findlay DM. Primary human osteoblasts grow into porous tantalum and maintain an osteoblastic phenotype. J Biomed Mater Res A. 2008;84(3):691-701. 64. Benson J. Elemental carbon as a bio-material. J Biomed Mater Res. 1971;5:41-47. 65. Kadefors R, Martin RI, Reswick JB. A percutaneous electrode for longterm monitoring of bio-electrical signals in humans. Med Biol Eng. 1970;8:129-135. 66. Markle DH, Grenoble DE, Melrose RJ. Histologic evaluation of vitreous carbon endosteal implants in dogs. Biomater Med Devices Artif Organs. 1975;3:97-114. 67. Cowland FC, Lewis JC. Vitreous carbon—a new form of carbon. J Mat Sci. 1967;2:507-512. 68. Stanitski CL, Mooney V. Osseous attachment to vitreous carbons. J Biomed Mater Res Symposium. 1973;4:97-108. 69 Anusavice KJ. Phillips’ Science of Dental Materials (Anusavice Phillip’s Science of Dental Materials). 11th ed. Philadelphia: Saunders Publishing, 2003. 70. International Organization for Standardization. Dentistry – Implants – Dynamic Fatigue Test for Endosseous Dental Implants (ISO 14801). Available online at: http://www.iso.org/iso/iso_catalogue.htm. Accessed 1 April 2010. 71. Ormianer Z, Palti A. Retrospective clinical evaluation of Tapered ScrewVent implants: results after up to eight years of clinical function. J Oral Implantol. 2008;34:150-160. 72. Lee CYS, Rohrer MD, Prasad HA. Immediate loading of the grafted maxillary sinus using platelet rich plasma and autogenous bone: a preliminary study with histologic and histomorphometric analysis. Implant Dent. 2008;17:59-73. 73. Ostman PO, Hellman M, Sennerby L. Direct implant loading in the edentulous maxilla using a bone density-adapted surgical protocol and primary implant stability criteria for inclusion. Clin Implant Dent Relat Res. 2005;7:S60-S69. 74. Fischer K, Bäckström M, Sennerby L. Immediate and early loading of oxidized tapered implants in the partially edentulous maxilla: a 1-year prospective, clinical, radiographic, and resonance frequency analysis tudy. Clin Implant Dent Relat Res. 2009;11:69-80. 75. Neugebauer J, Weinländer M, Lekovic V, von Berg KH, Zoeller JE. Mechanical stability of immediately loaded implants with various surfaces and designs: a pilot study in dogs. Int J Oral Maxillofac Implants. 2009;24:1083-1092. 76. Hui E, Chow J, Li D, Liu J, Wat P, Law H. Immediate provisional for single-tooth implant replacement with a Brånemark system: preliminary report. Clin Implant Dent Relat Res. 2001;3:79-82. 77. Achilli A, Tura F, Euwe E. Immediate/early function with tapered implants supporting maxillary and mandibular posterior fixed partial dentures: preliminary results of a prospective multicenter study. J Prosthet Dent. 2007;97:S52-S58. 78 Calandriello R, Tomatis M, Rangert B. Immediate functional loading of Brånemark System implants with enhanced initial stability: a prospective 1- to 2-year clinical and radiographic study. Clin Implant Dent Relat Res. 2003;5:10-20. 79 Cannizzaro G, Torchio C, Leone M, Esposito M. Immediate versus early loading of flapless-placed implants supporting maxillary full-arch prostheses: a randomised controlled clinical trial. Eur J Oral Implantol. 2008;1:127-139.

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80. Anusavice KJ. Phillips’ Science of Dental Materials (Anusavice Phillip’s Science of Dental Materials). 11th ed. Philadelphia: Saunders Publishing, 2003. 81. International Organization for Standardization. Dentistry – Implants – Dynamic Fatigue Test for Endosseous Dental Implants (ISO 14801). Available online at: http://www.iso.org/iso/iso_catalogue.htm. Accessed 1 April 2010. 82. Lekholm U, Zarb GA. Patient selection and preparation. In: Brånemark PI, Zarb GA, Albrektsson T (Eds.): Tissue-Integrated Prostheses. Osseointegration in Clinical Dentistry. Chapter 12. Chicago: Quintessence Books, 1985:199-209. 83. Le Gall MG. Localized sinus elevation and osteocompression with single-stage tapered dental implants: technical note. Int J Oral Maxillofac Implants. 2004;19:431-437. 84. Skalak R, Zhao Y. Interaction of force-fitting and surface roughness of implants. Clin Implant Dent Relat Res. 2000;2:219-234. 85. Callan DP, Hahn J, Hebel K, Kwong-Hing A, Smiler D, Vassos DM, Wöhrle P, Zosky J. Retrospective multicenter study of an anodized, tapered, diminishing thread implant: success rate at exposure. Implant Dent. 2000;9:329-336.

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86. Kim D-G, Huja SS, Larsen PE, Kreuter KS, Chien H-H, Joo W, Wen HB. Trabecular Metal dental implants in an animal model. Abstract No. 1511. Presented at the Annual Meeting of the American Association for Dental Research, Washington, DC, USA, March 3-6, 2010.

© 2012 Zimmer Dental Inc. All rights reserved. 2096, Rev. 12/11. Last-AFoam® is a registered trademark of General Plastics Manufacturing Company. NobelReplace® and NobelActive® are registered trademarks of Nobel Biocare AB. SLActive® is a registered trademark of Straumann Holding AG.

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Implant therapy with an innovative surface (trabecular metal™) and CAD/CAM restorations – a clinical case Kai Fischer*, Stefan Fickl** In the past, just as today, the success and progressive spread of dental implants have been underpinned by multiple innovations and ongoing development. These include, for example, the development of rough surfaces, various lifting techniques and digital technology in the sphere of planning and rehabilitation. These milestones have determined the success of dental implantology. Given that various prospective studies actually show implant survival rates of over 95%, it is clear that there is now little room for innovation. Despite this, through the development of innovative surfaces and designs, it is nevertheless possible to reduce healing times, promote bone regeneration and allow more predictable therapies even in high-risk groups were bone healing is slowed or reduced. This case describes an operation conducted on a patient to whom a new implant design with internal sinus lift and computerised restoration was applied. More specifically, it describes the possible advantages of the surface, any indications and goals for new investigations. Key Words: Implant design, Trabecular metal, Sinus lift via a crestal approach, Osseointegration, CAD/CAM technology.

Introduction Nowadays, ongoing developments and study into surfaces, abutment connections, lift techniques and prosthetic restoration options make it possible for missing dental elements to be replaced by implants with few contraindications. The implant survival rate in various prospective studies is greater than 95%1-4 and this therefore represents a highly successful therapeutic option. From a clinical viewpoint, when faced with the evidence of such statistics, a question mark arises over the benefits an implant producer could gain in terms of achieving even more predictable results through new developments or presumed innovations, and whether switching to a new system could offer * Dr. med. dent., Department of Periodontology at the Würzburg University Clinic Conservative Dentistry and Periodontology Polyclinic Pleicherwall 2 - 97070 Würzburg. **  PD Dr. med. dent., Department of Periodontology at the Würzburg University Clinic Conservative Dentistry and Periodontology Polyclinic Pleicherwall 2 - 97070 Würzburg. Correspondence: Kai Fischer Department of Periodontology at the Würzburg University Clinic Conservative Dentistry and Periodontology Polyclinic Pleicherwall 2 - 97070 Würzburg T: +49-931/20172570 • E-mail: [email protected]

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any benefits. The spread of new and modified surfaces nevertheless shows that, particularly in limit situations (implants with lift, immediate implants, patients with systemic diseases) there is still always room for potential improvement5-7. For example, the transfer of trabecular metal™ technology from orthopaedics to dentistry represents an interesting shift away from conventional surfaces that must be confirmed by clinical studies in coming years.

Case presentation Medical history & report The following case describes the treatment of a 70-year-old patient without severe systemic diseases, who only suffers from slight controlled hypertonia. The patient also follows regular maintenance therapy against periodontitis and has never been a smoker. Tooth 24 had been rehabilitated with endodontic and prosthetic treatment but was nevertheless subsequently extracted due to a crown fracture. To overcome natural resorption of the bone ridge8-10, the root was extracted by means of a non-traumatic technique and a socket preservation method was applied with allergen-

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ic bone substitute (KEM; Puros®, Zimmer Dental GmbH, Frieburg, Germany). The implant therapy described below was carried out after a six-month healing period. Implant with sinus lift via a crestal approach Based on a digital panoramic dental x-ray (PSA; Fig. 1) insertion of an implant (Zimmer trabecular metal™, 4.1 x 11.5 mm) was planned and carried out in zone 24 after lifting the sinus via a crestal approach. One hour before the operation was carried out on the patient, 2g of amoxicillin was administered for anti-infective prophylaxis11. After local anaesthesia (4% Articaine, 1:100.000 Epinephrine), work began on exposing the implant site and good consolidation of the bone lift was noted with only marginal buccal resorption (Fig. 2, 3). After preparing the implant site up to the cortical margin of the maxillary sinus, the floor of the sinus was fractured using an osteotome and Schneider’s membrane (Fig. 4, 5) was slightly lifted, without

inserting KEM replacement bone material. It was possible to insert the implant with high primary stability (> 50 N/cm) in the correct three-dimensional position (Fig. 6, 7). A near multi-layer suture was applied by means of double sling suturing12 and a non-resorbable suture material (5-0 PTFE, Cytoplast™ Suture, Osteogenics Biomedical, Lubbock, USA) (Fig. 8). After the operation a follow-up OPT was performed with the typical implant configuration used in the X-ray (Fig. 9). This also showed that the implant was inserted by approximately 2 mm mesially and 4 mm distally into the maxillary sinus. Ten days after the operation, the suture stitches were removed and remodelling was found to be primary and without complications (Fig. 10). Prosthetic rehabilitation After a healing stage of ten weeks, prosthetic rehabilitation of the implants was performed. The roll flap technique was used to improve buccal soft tissue

Fig 2 Clinical image prior to implementation; slight buccal invagination.

Fig 1 OPT following socket preservation & implementation technique in zone 24; contained vertical bone deficit.

Fig 3 Situation of the bone ridge; sufficient horizontal bone availability and good integration of the allogeneic KEM.

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Fig 4 Implant site preparation by means of a twist drill with internal cooling.

Fig 5 Fracture of the maxillary sinus floor using an osteotome; no additional KEM inserted.

Fig 7 Occlusal aspect of the correctly housed implant.

Fig 6 Insertion of the implant (Zimmer Trabecular Metal™, 4.1 x 11.5 mm).

Fig 8 Primary suture by means of double sling suturing.

Fig 9  Post-implant OPT; the implant penetrates 2-4 mm into the maxillary sinus. Fig 10 Wound remodelling without complications and removal of suture stitches after 10 days.

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Fig 11 Roll flap technique for adding bulk to the buccal soft tissues.

Fig 12  Thickening of the buccal tissue and insertion of healing screw.

Fig 13 Digital prosthetic manufacture with abutment and crown.

Fig 14 Abutment in zirconium based on titanium in situ.

Fig 15 Integrated e.max restoration.

Fig 16 OPT after prosthetic application; bone regeneration around the implant in the maxillary sinus area; vertical fracture of dental element 15 and radiotransparent halo in zone 48.

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bulk13. For this purpose, the gum above the implant was initially detached, incised and rotated in a buccal direction (Fig. 11, 12). The implant had taken root and was osseointegrated. Since the patient is easily subject to the gag reflex, two weeks after exposure, an impression was taken of the implant by means of an intraoral scanner (Zfx Intrascan, Zfx GmbH, Dachau). The digital impression made it possible to produce an abutment in zirconium oxide with adhesive basic titanium and to design and produce an e.max crown (Fig. 13). Only 14 weeks after inserting the implant, it was possible to insert the prosthetic product (Fig. 14, 15), while an x-ray check showed good bone regeneration around the implant in the area of the surface that was previously free (Fig. 16).

Conclusion Implants represent a successful therapeutic option for the replacement of missing dental elements, with a survival rate of approximately 95% for over five years1-4. It is nevertheless also necessary to consider technical complications (loosening of screws, chipping etc.) and biological complications (perimucositis, peri-implantitis). Given the high advertised survival rate, a question inevitably arises over the extent to which innovations in the implant surface can allow an additional increase in predictability. The development of implant surfaces has shown that the nanostructure of an implant as well as its microstructure has an effect on bone remodelling and that moderately rough surfaces take root better than smooth surfaces or extremely rough implants.14 By modifying the micro and macrostructures of dental implants, it also appears to be possible to achieve progress, above all with regard to loading protocols, bone lifting and operations on high-risk patients, The application or rather the transfer of trabecular metal™ technology from orthopaedics to dental implant dentistry constitutes an interesting development in the field of surface structure. This technology has been successfully applied for many years in orthopaedics within the endoprosthetic field and is characterised by high stability, biocompatibility, porosity and friction15-17, which are also properties required in dental implantology. As with spongy tissue, the three-dimensional structure allows osseointegration – in other words bone adhesion – and also bone interpenetration (Hrst.: “osseoincorporation”) with the implant. In this

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way, stabilisation of the blood coagulum is improved during the bedding-in stage in other words distribution of the masticatory load subsequent to osseointegration. The cells that promote bone growth, or bone fragments can also remain during implant insertion and thus contribute to more rapid bone regeneration starting from the implant. Apart from this, the greater volume may also be an advantage, particularly in implants of reduced diameter or in short implants. We nevertheless also need to clarify whether the need for an open implant could affect the success of this technique. To conclude, the case presented shows successful implant treatment with maxillary sinus lift and restoration supported by CAD/CAM technology in a seventy year-old patient. The extent to which trabecular metal™ technology contributed to the success must be examined by means of randomised prospective studies in order to definitely demonstrate the long-term success and advantage of this technology.

Literature   1. Jung RE, Pjetursson BE, Glauser R, Zembic A, Zwahlen M, Lang NP. A systematic review of the 5-year survival and complication rates of implant-supported single crowns. Clin Oral Implants Res. 2008;19(2):11930. Epub 2007/12/11.   2. Pjetursson BE, Bragger U, Lang NP, Zwahlen M. Comparison of survival and complication rates of tooth-supported fixed dental prostheses (FDPs) and implant-supported FDPs and single crowns (SCs). Clin Oral Implants Res. 2007;18 Suppl 3:97-113. Epub 2007/06/28.   3. Pjetursson BE, Tan WC, Zwahlen M, Lang NP. A systematic review of the success of sinus floor elevation and survival of implants inserted in combination with sinus floor elevation. J Clin Periodontol. 2008;35(8 Suppl):216-40. Epub 2008/09/09.   4. Clementini M, Morlupi A, Canullo L, Agrestini C, Barlattani A. Success rate of dental implants inserted in horizontal and vertical guided bone regenerated areas: a systematic review. International journal of oral and maxillofacial surgery. 2012;41(7):847-52. Epub 2012/05/01.   5. Calvo-Guirado JL, Ortiz-Ruiz AJ, Negri B, Lopez-Mari L, RodriguezBarba C, Schlottig F. Histological and histomorphometric evaluation of immediate implant placement on a dog model with a new implant surface treatment. Clin Oral Implants Res. 2010;21(3):308-15. Epub 2010/01/16.   6. Schwarz F, Herten M, Sager M, Wieland M, Dard M, Becker J. Bone regeneration in dehiscence-type defects at chemically modified (SLActive) and conventional SLA titanium implants: a pilot study in dogs. J Clin Periodontol. 2007;34(1):78-86. Epub 2006/12/02.   7. Mardas N, Schwarz F, Petrie A, Hakimi AR, Donos N. The effect of SLActive surface in guided bone formation in osteoporotic-like conditions. Clin Oral Implants Res. 2011;22(4):406-15. Epub 2011/02/10.   8. Schropp L, Wenzel A, Kostopoulos L, Karring T. Bone healing and soft tissue contour changes following single-tooth extraction: a clinical and radiographic 12-month prospective study. Int J Periodontics Restorative Dent. 2003;23(4):313-23. Epub 2003/09/06.   9. Fickl S, Zuhr O, Wachtel H, Stappert CF, Stein JM, Hurzeler MB. Dimensional changes of the alveolar ridge contour after different socket preservation techniques. J Clin Periodontol. 2008;35(10):906-13. Epub 2008/08/21. 10. Tan WL, Wong TL, Wong MC, Lang NP. A systematic review of postextractional alveolar hard and soft tissue dimensional changes in humans. Clin Oral Implants Res. 2012;23 Suppl 5:1-21. Epub 2012/01/11.

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11. Esposito M, Worthington HV, Loli V, Coulthard P, Grusovin MG. Interventions for replacing missing teeth: antibiotics at dental implant placement to prevent complications. Cochrane Database Syst Rev. 2010(7):CD004152. Epub 2010/07/09. 12. Wachtel H, Fickl S, Zuhr O, Hurzeler MB. The double-sling suture: a modified technique for primary wound closure. Eur J Esthet Dent. 2006;1(4):314-24. Epub 2006/01/01. 13. Hurzeler MB, von Mohrenschildt S, Zuhr O. Stage-two implant surgery in the esthetic zone: a new technique. Int J Periodontics Restorative Dent. 2010;30(2):187-93. Epub 2010/03/17.

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14. Wennerberg A, Albrektsson T. Effects of titanium surface topography on bone integration: a systematic review. Clin Oral Implants Res. 2009;20 Suppl 4:172-84. Epub 2009/08/12. 15. Levine B, Della Valle CJ, Jacobs JJ. Applications of porous tantalum in total hip arthroplasty. The Journal of the American Academy of Orthopaedic Surgeons. 2006;14(12):646-55. Epub 2006/11/02. 16. Levine B, Sporer S, Della Valle CJ, Jacobs JJ, Paprosky W. Porous tantalum in reconstructive surgery of the knee: a review. The journal of knee surgery. 2007;20(3):185-94. Epub 2007/08/02. 17. Cohen R. A porous tantalum trabecular metal: basic science. Am J Orthop (Belle Mead NJ). 2002;31(4):216-7. Epub 2002/05/15.

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Immediate post-extraction provizionalisation: aesthetic and functional stability after 13 years Bruno Fissore* Extractions and immediate implants with temporary crowns provide many benefits for patients. Treatment times are simplified and shortened, and the issue of temporary prosthetic replacement is solved. The monitoring of a maxillary central incisor, carried out over 13 years following its replacement, showcases the results of this technique after several years. Its success is due particularly to excellent implant primary stability and to the presence of bone. This clinical case confirms that gingival recession is one of the most frequent long-term complications. The provision of substitute bone filling as well as the placement of a connective graft can contribute to reducing the risk of gingival recession. Keywords: Extraction, Dental implant, Immediate implant, Immediate provizionalisation, Immediate temporary crown, Aesthetic, Gingival recession, Clinical case, Long-term.

Introduction Extraction site management is a recurring theme in scientific literature. Wohrle was one of the first clinicians to present extraction, implant and immediate temporary restoration cases in 19981. There are many benefits to immediate post-extraction provizionalisation. This technique provides simpler and shorter treatment times. It also constitutes a very interesting approach to the issue of temporary prosthetic replacement and to post-extraction tissue preservation. Grutter published a literature review on the implant loading protocol for partially toothless aesthetic areas2. In the 21 studies representing 758 implants inserted in *  Docteur en chirurgie dentaire, DDS, MSD, Private practice, Monte-Carlo, Monaco. Correspondence: Bruno Fissore Avenue Saint Michel, Monte-Carlo Principauté de Monaco MC98000 E-mail: [email protected]

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recent and immediately restored extraction sites, a general survival rate of 96,6% for a maximum period of 60 months was reported. Observation periods in these types of studies are still quite short, and little information is available regarding these cases’ longterm outcome. This article aims to present the treatment and evolution pertaining to the replacement of a female patient’s maxillary central incisors over 13 years in order to assess this technique’s short-term, but also long-term aesthetic and functional benefits.

Case presentation This 64 year-old female patient, with a low smile line, features an upper central incisor with a large parodontal lesion, a 2 mm gingival recession (Fig. 1 and 2) as well as class III mobility and sensitivity during chewing. The observation of the periapical x-ray shows that the root is short and that the vertical bone loss is limited to the tooth’s mesial area. Over 5 millimeters of bone are available at the top of the tooth to be ex-

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tracted. This patient features a class I angle occlusion and isn’t subject to bruxism. An observation of the diagnosis elements shows it is possible to obtain excellent primary stability through the use of a long implant. On the other hand, the vestibular gingival situation is not very favorable, due to gingival level discrepancies between both central incisors (Fig. 1). The patient’s smile doesn’t uncover the tooth neck area, her aesthetic expectations are reasonable and she wishes above all to avoid wearing a transitional removable prosthesis. In order to meet her expectations and following the observation of all parameters, the decision was made to proceed with an immediate post-extraction implant, with an immediate placement of a temporary crown. This way, the patient undergoes less surgery and the treatment period is reduced.

A wide, 16-millimetre long, cylindrical and selftapping screwed implant (Zimmer Dental) is placed in parallel to the adjacent teeth and against the palatine bone wall in order to increase the distance between the implant and the vestibular bone wall (Fig. 3). The temporary restoration is sealed using strong temporary cement (IRM, Caulk) on a machined screw-retained abutment (Fig. 4). The final restoration is carried out via a ceramic metallic screw-retained one-piece part (Fig. 5 and 6). The restoration features good soft tissue stability (Fig. 7), and 3 years later, the x-ray shows good implant osseointegration (Fig. 8) After six and a half years, the vestibular clinical view shows a 1 mm gingival recession on the implant, as well as on the left adjacent incisor (Fig. 9). The palatine view shows an 11 mm distal parodontal pocket on the right central incisor (Fig. 10). The bone situation re-

Fig 2 Periapical x-ray showing this tooth’s bone loss.

Fig 1 Initial clinical situation of left central incisor 21. Note the gingival recession on the left central incisor.

Fig 3  Occlusal view of the implant placed with no flap immediately after extraction.

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Fig 4 Immediate temporary crown.

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Fig 6 Periapical x-ray with permanent restoration at the end of the treatment.

Fig 5 One-piece ceramic metallic restoration at the end of the treatment.

Fig 7 Permanent restoration after three months in operation.

Fig 8  Vestibular view of the permanent restoration after six and a half years.

Fig 9 Periapical x-ray after three years.

Fig 10 Occlusal view of the permanent restoration with the parodontal lesion shown on right central incisor 11.

Fig 11 Vestibular view after the flap is lifted and extraction of 11. Note there is no bone at vestibular level for 21.

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mains favorable and allows a similar treatment to the one carried out on the left central incisor. The procedure shall be carried out using a flap allowing access to the adjacent implant’s vestibular aspect. A 3 mm wide bone dehiscence spreads over the first three implant threads (Fig. 11). A wide, 13 mm long, conical self-screwed implant (Zimmer Dental) is

placed (Fig. 12). The implant site is prepared against the socket’s palatine wall and doesn’t follow its angulation as this would lead to outer bone perforation. The drilling is of smaller dimension than the implant’s diameter. The space separating the implant and the socket’s inner wall is filled using a xenograft (Bio-Oss®, Geistlich). The temporary restoration is sealed (Fig. 13)

Fig 12 Implant placement on 11.

Fig 13  Immediate temporary crown on the implant and filling of the residual space between the implant and the vestibular bone with a xenograft.

Fig 14 Flaps are sutured on 21 with a connective graft on the vestibular.

Fig 15 Vestibular view after the ceramic metallic crown is placed on 11.

Fig 16  X-ray of both central teeth after the ceramic metallic crown is placed on 11.

Fig 17 Vestibular view of 21 after 13 years and of 11 after six and a half years.

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Fig 18  Periapical xray of 21 after 13 years and of 11 after six and a half years.

and a connective tissue graft is placed on implant 21 before suturing (Fig. 14). The final restoration carried out on implant 11 is also a ceramic metallic screw-retained one-piece crown (Fig. 15 and 16). Checks carried out after 13 years for implant 21 and after six and a half years for implant 11 showed excellent soft tissue stability (Fig. 17). A radiological examination also showed an excellent bone level for both implants (Fig. 18).

Discussion Successive periapical x-rays carried out for both implants showed almost perfect bone stability. The patient was completely satisfied with both restorations; however, a 1 mm gingival recession was observed after six years on implant 21. Kan observed in a prospective study running over two to eight years that such gingival recession is very common3. The assessment of our implants’ success can’t only be based on periapical x-rays. Indeed, stable radiological bone levels don’t always entail soft tissue stability. Periapical x-rays don’t provide information regarding vestibular or palatine bone levels. Nowadays, the use of tridimensional radiological techniques should provide more accurate information on the implants’ bone situation4. Longterm soft tissue stability should also be acknowledged as a key contributor to the success of our implants. Soft tissue instability is a multifactorial phenomenon. Inappropriate handling of soft or hard tissue, or an excessively vestibular implant position are among these factors. The implant was placed with a palatine

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angulation, allowing for the use of a one-piece ceramic metallic crown with a palatine access to the screw. However, no filling material was used to fill the space between the implant and the socket’s bone wall. The implant’s placement doesn’t prevent the post-extraction bone reduction, and a ridge vestibular palatine reduction is observed as demonstrated by Covani5. A bone lysis, on a small part of the implant’s vestibular face, may have contributed to this gingival recession. Implant 11, placed six and a half years later, is associated with residual vestibular hiatus filling, and during this procedure, a connective tissue graft was placed on implant 21. During the six and a half years following this procedure, excellent hard tissue stability was observed, as well as soft tissue stability on both implants. This confirms the need to fill the space between the implant and the socket’s vestibular wall6, as well as to thicken soft tissue in order to increase its stability3,7. In such a clinical space, the gingival graft was carried out post factum in a less favorable vestibular bone dehiscence situation, threads exposed, which didn’t prevent clinical success.

Conclusion The clinical case presented features excellent bone and gingival stability over 13 years for one implant, and 6 and a half years for the other. This technique’s success is due to compliance with fundamental criteria such as high primary stability and the presence of the vestibular bone. The vestibular gingival level may vary over time. Should a recession occur, regular check-ups allow for monitoring and early intervention. These recession risks are mitigated by the use of filling material to fill the space between the implant and the outer alveolar wall, as well as by the implementation of connective tissue grafts.

BIBLIOGRAPHY   1. Wohrle P S: Single-tooth replacement in the aesthetic zone with immediate provizionalisation : Fourteen consecutive case reports. Pract Periodontics Aesthet Dent 1998;10 :1107-1114.   2. Grutter L, Belser U C: Implant loading protocols for the partially edentulous aesthetic zone. Int J Oral Maxillofac Implants. 2009;24(Suppl):169-179.   3. Kan J Y K, Rungcharassaeng K, Lozada J L, Zimmerman G: Facial gingival tissue stability following immediate placement and provisionalization of maxillary anterior single implants: A 2- to 8- year follow up. Int J Oral Maxillofac Implants 2011;26:179-187.

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  4. Vera C, De Kok I J, Reinhold D, Limpiphipatanakorn P, Yap A K W, Tyndall D, Cooper L F: Evaluation of buccal alveolar bone dimension of maxillary anterior and premolar teeth: A cone beam computed tomography investigation. Int J Oral Maxillofac Implants 2012;27:1514-1519.   5. Covani U, Cornellini R, Barone A: Bucco-Lingual bone remodeling around implant placed into immediate extraction sockets: A case series. J Periodontol 2003; 74:268-273.

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  6. Chen S T, Darby I B, Reynolds E C: A prospective clinical study of non submerged immediate implants: clinical outcomes and aesthetic results. Clin Oral Impl Res 2007; 18:552-562.   7. Kan Y K, Rungcharassaeng K, Morimoto T, Lozada J: Facial gingival tissue stability after connective tissue graft with single immediate tooth replacement in the aesthetic zone: Consecutive case report. J Oral Maxillofac Surg 2009; 67(supl3):40-48.

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Simultaneous TM implant placement and horizontal ridge augmentation with IngeniOs HA: A Case Report Ramón Gómez Meda* A single case report is presented that involves lateral augmentation of an edentulous atrophic posterior mandibular alveolar ridge to facilitate dental implant placement. A new, highly porous non-biologic hydroxyapatite bone graft material, IngeniOs HA (Zimmer Dental Inc., Carlsbad, CA) was used and covered by a resorbable barrier membrane ( Copios Membrane-Zimmer Dental Inc., Carlsbad, CA) . Two bone-level Trabecular Metal Dental Implants (Zimmer Dental Inc., Carlsbad, CA, USA) were positioned at the same time of the GBR procedure in order to improve bone apposition, due to the potential for the bone to grow not only on the implant surface, but also inside the material’s pores, in a new process called “Osseoincorporation”. Key Words: Alveolar bone loss, Augmentation, Immediate placement, Implant.

INTRODUCTION Reduced function due to long-standing edentulousness is known to induce skeletal change such as residual ridge resorption1,2. For some patients implant treatment would not be an option without the variety of materials and surgical techniques that are available for bone augmentation today3-10. Every surgical procedure presents advantages and disadvantages. Priority should be given to those procedures that are simplest, least invasive and able to reach their goals within the shortest time frame with minimum risks of complications.

*  Private Practice of Periodontics and Prosthodontics, León, Spain. Correspondence: Ramón Gómez Meda Avda Pérez Colino 13, 2º B 24402 Ponferrada-León- Spain E-mail: [email protected]

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A new synthetic material developed for bone regeneration consists of bioceramic granules of non-biologic origin (IngeniOs® HA Synthetic Bone Particles, Zimmer Dental Inc., Carlsbad, CA, USA). Made of phase-pure hydroxyapatite (HA) with an open sintering structure, the material is both biocompatible and osteoconductive. The material’s origin and the ceramic sintering process result in a material that is free of germs and pyrogens, and the potential for antigeneic response can be precluded. In addition to augmenting the quantity and quality of available bone, research has also focused on methods to improve the quality of the implant’s surface through various modification techniques, such as coating with hydroxyapatite (HA), titanium plasma spray (TPS) or porous beads, grit-blasting with various media, acid-etching or a combination of procedures11. Intense research activity over the last decade led to the development of a new titanium dental implant (Trabecular Metal® Dental Implant, Zimmer Dental Inc.) with a midsection covered by a highly porous tantalum material (TM) that has a structure and stiffness14 similar

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to trabecular bone. Tantalum is a highly biocompatible metal that has been widely used for numerous types of human implants: dental, orthopedic, ligating clips, plates, nets, wires, etc, in various medicine specialties, such as neurosurgery, cardiology, maxillofacial surgery12,13. Therefore, its application in medicine is not new. The implant was designed to enhance bone growth not only on the implant surface, but also inside the tantalum structure, which is a process called “Osseoincorporation.” This article reports on a case where the new, highly porous non-biologic HA bone graft material was used for horizontal ridge augmentation in the mandible immediately after placement of 2 TM dental implants.

REPORT A 66-year-old male presented to the dental office with a complaint of a toothache of several days’ duration associated with the mandibular left third molar. The tooth served as a distal support and the left first premolar served as the mesial support for a fixed partial denture restortion. Periodontal examination

Fig 1 Preoperative ortopantomography.

indicated slight plaque-induced gingivitis. Occlusal analysis revealed bilateral group function with obvious occlusal wear on all remaining teeth; the patient admitted to a clenching habit. A cone beam computed tomography (CBCT) scan showed that the ridge measured 3 mm in the horizontal dimension and confirmed the diagnosis of a radicular fracture of the mandibular left third molar. A review of the patient’s medical history was essentially negative and his health status was classified as ASA 1. The details of the case were discussed and the patient was informed that, to achieve successful implant placement, a horizontal ridge augmentation procedure would be necessary (Fig. 2). During phase 1 of the treatment, the prosthesis was removed and the mandibular left third molar was extracted. After a period of 8 weeks to allow adequate soft tissue healing (Fig. 1), anesthesia was achieved via localized injections using 2 carpules of articaine HCl/ epinefrin (Ultracain®, Sanofi-Aventis Deutschland GmbH Germany) (40/0,005 mg/mL) with 1:100,000 epinephrine. Following anesthesia, buccal and lingual intrasulcular incisions were made, starting at the distal of the canine and joined at the distal of the first premolar

Fig 2 Oclusal view of the area after a heling period of 8 weeks. Fig 3 TM implant placement (4.7 X 10 mm) after perforation of the cortical bone to reach the alveolar bone.

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to become a single crestal incision extending distally up the anterior border of the mandibular ramus. This incision design allowed for a relaxed full-thickness mucoperiosteal flap reflection and exposure of the underlying bony ridge, confirming the Seibert Class III defect, the horizontal dimension of approximately 3 mm, and the buccal slant. Shallow indentations were made in the buccal cortical plate with a #4 carbide round bur to reach the cancellous bone and facilitate the revascularization of the grafted site (Fig. 3). Two TM dental implants (4.7 x 10 mm) were placed in the position of the second premolar and second molar in order to use them as supports for a fixed partial denture restoration (Fig. 4). A graft of the alloplastic HA particles was used to cover the 3-4 mm of exposed implant surface (Fig. 4-6). The graft site was then covered with a bovine pericardium membrane (Puros® CopiOs®, Zimmer Dental) tucked under both the lingual

and buccal mucoperiosteal flaps (Fig. 7). The buccal flap was released slightly by two periosteal releasing incisions without vertical components to insure blood supply. Primary closure was obtained and stabilized with sutures (Supramid 4-0, LorcaMarín, S.A. Murcia - Spain) using a continuous interlocking technique. The patient was placed on prophylactic antibiotics (amoxicillin 500 mg, t.i.d.) for 10 days and instructed to use an alcohol-free chlorhexidine oral rinse twice a day for three weeks. Sutures were removed at 2 weeks postoperative. Following a 6-month healing period, the site was reentered and ridge measurements were taken. The initial measurement of a 3 mm atrophic ridge was expanded to 9 mm following the surgery (Fig. 8). Healing collars were screwed on the implants. The bone appeared to be well vascularized and to exhibit good density. The graft site appeared to be healed and the implants were osseointegrated (Figs. 8-10). Definitive

Fig 4 Bone augmentation was needed to cover the 3-4 mm of exposed implant surface after placement.

Fig 5 Occlusal view of the ridge shows atrophy of alveolar process.

Fig 6  IngeniOs placed on the bucal side of the crestal ridge.

Fig 7 Baseline radiograph taken immediately after surgery.

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restoration of the implants was achieved 2 months after the second stage surgery (Figs. 11). Following restoration of the implants, the patient was fitted with a mouth guard to counter the biomechanical stresses

from the clenching habit. Follow-up evaluations were conducted at1,3,6,12 and 18 months post-restoration (Figs. 12-13). The expectations of the patient as well as the clinician were completely achieved.

Fig 8  View of the regenerated area at reentry point (six months after surgery).

Fig 9  Extraction of a biopsy sample, whose results is shown in the right figure.

Fig 10  Histology shows new bone growing around the bone graft particles (hematoxylin-eosin).

Fig 11 Radiograph taken 2 months after reentry.

Fig 12 18 months follow-up photography.

Fig 13 Radiograph taken 18 months after prosthesis placement.

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DISCUSSION

ACKNOWLEDGMENTS

Autografts remain the gold standard15-17 of bone graft materials because they contain the needed osteoinductive, osteogenic and osteoconductive properties necessary to regenerate bone for implant placement. However, there are drawbacks to harvesting autografts, including increased operating time, potential complications and morbidity of the harvested site. And limitations in available bone quantity. In addition, the type of bone available (cortical or cancellous), the quality of the bone (density) and the final amount (quantity) of the harvested bone can also make the use of autografts problematic. Due to these limitations there has been significant effort placed on the development of various categories of alloplastic bone graft substitutes, including calcium phosphate and hydroxyapatite materials, bioactive glasses, as well as other materials from allogeneic and xenogeneic materials18,19. The bone graft substitute used in the present case effectively regenerated the patient’s horizontally resorbed ridge without exposing the patient to additional risk of antigeneic response that could potentially occur with bone graft materials from biologic sources. The dental implants were selected for this case because of their potential to improve bone apposition through conventional osseointegration and bone ingrowth into the porous of the tantalum material (osseoincorporation). It was effective in the present case for use as bridge supports in a horizontal bone atrophy scenario, and generally in situations where the bone quality and quantity are poor. The alloplastic bone graft material was also effective in expanding and maintaining the bone in order to to establish the structural base of osseous tissue for supporting dental implants. The ability to combine the procedures in one surgical step reduced psychological, economic and time costs for the patient, and shortened treatment time.

This clinical case is part of a European clinical research study sponsored by Zimmer Dental Inc. in which the authors are participating. The author would like to thank Marco Baiguini for his help and valuable comments in the elaboration and translation of the present text.

CONCLUSIONS The simultaneous use of Trabecular Metal Dental Implants and IngeniOs HA synthetic bone graft material simplified clinical rehabilitation of the posterior atrophic mandible with high predictability. More studies are neccessary to complement this finding.

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REFERENCES   1. Gholami GA, Najafi B, Mashhadiabbas F, Goetz W, Najafi S. Clinical, histologic and histomorphometric evaluation of socket preservation using a synthetic nanocrystalline hydroxyapatite in comparison with a bovine xenograft: a randomized clinical trial. Clinical oral implants research. Oct;23(10):1198-204.   2. Trombelli L, Farina R, Marzola A, Bozzi L, Liljenberg B, Lindhe J. Modeling and remodeling of human extraction sockets. J Clin Periodontol. 2008 Jul;35(7):630-9.   3. Aghaloo TL, Moy PK. Which hard tissue augmentation techniques are the most successful in furnishing bony support for implant placement? The International journal of oral & maxillofacial implants. 2007;22 Suppl:49-70.   4. Esposito M, Grusovin MG, Felice P, Karatzopoulos G, Worthington HV, Coulthard P. Interventions for replacing missing teeth: horizontal and vertical bone augmentation techniques for dental implant treatment. Cochrane Database Syst Rev. 2009(4):CD003607.   5. Basa S, Varol A, Turker N. Alternative bone expansion technique for immediate placement of implants in the edentulous posterior mandibular ridge: a clinical report. The International journal of oral & maxillofacial implants. 2004 Jul-Aug;19(4):554-8.   6. Misch CM. Comparison of intraoral donor sites for onlay grafting prior to implant placement. The International journal of oral & maxillofacial implants. 1997 Nov-Dec;12(6):767-76.   7. Pikos MA. Block autografts for localized ridge augmentation: Part II. The posterior mandible. Implant Dent. 2000;9(1):67-75.   8. Chiapasco M, Casentini P, Zaniboni M. Bone augmentation procedures in implant dentistry. The International journal of oral & maxillofacial implants. 2009;24 Suppl:237-59.   9. Buser D, Dula K, Hirt HP, Schenk RK. Lateral ridge augmentation using autografts and barrier membranes: a clinical study with 40 partially edentulous patients. Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 1996 Apr;54(4):420-32; discussion 32-3. 10. Jensen SS, Terheyden H. Bone augmentation procedures in localized defects in the alveolar ridge: clinical results with different bone grafts and bone-substitute materials. The International journal of oral & maxillofacial implants. 2009;24 Suppl:218-36. 11. Ring ME. A thousand years of dental implants: a definitive history-part 2. Compend Contin Educ Dent. 1995 Nov;16(11):1132, 4, 6 passim. 12. Wigfield C, Robertson J, Gill S, Nelson R. Clinical experience with porous tantalum cervical interbody implants in a prospective randomized controlled trial. Br J Neurosurg. 2003 Oct;17(5):418-25. 13. Unger AS, Lewis RJ, Gruen T. Evaluation of a porous tantalum uncemented acetabular cup in revision total hip arthroplasty: clinical and radiological results of 60 hips. J Arthroplasty. 2005 Dec;20(8):1002-9. 14. Black J. Biological performance of tantalum. Clin Mater. 1994;16(3):167-73. 15. Donos N, Mardas N, Chadha V. Clinical outcomes of implants following lateral bone augmentation: systematic assessment of available options (barrier membranes, bone grafts, split osteotomy). J Clin Periodontol. 2008 Sep;35(8 Suppl):173-202. 16. McAllister BS, Haghighat K. Bone augmentation techniques. J Periodontol. 2007 Mar;78(3):377-96.

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17. Donos N, Kostopoulos L, Tonetti M, Karring T. Long-term stability of autogenous bone grafts following combined application with guided bone regeneration. Clinical oral implants research. 2005 Apr;16(2):133-9. 18. Kruse A, Jung RE, Nicholls F, Zwahlen RA, Hammerle CH, Weber FE. Bone regeneration in the presence of a synthetic hydroxyapatite/silica oxide-based and a xenogenic hydroxyapatitebased bone substitute material. Clinical oral implants research. May;22(5):506-11.

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19. Santos FA, Pochapski MT, Martins MC, Zenobio EG, Spolidoro LC, Marcantonio E, Jr. Comparison of biomaterial implants in the dental socket: histological analysis in dogs. Clin Implant Dent Relat Res. Mar;12(1):18-25.

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High resolution histologic and histomorphometric analysis of block allografts in humans: Report of three cases Dr. W. Gutwerk* Background: Block allografts are an accepted alternative to autogenous bone block for ridge reconstruction. The present case series quantifies the graft remodeling and new bone formation of cortico-cancellous block allografts. Methods: Three patients underwent ridge reconstruction (two patients upper jaw, one patient lower jaw) with mineralized, cortico-cancellous block allografts. After healing time of at least 6 months a second-stage surgery was performed and implants have been placed. A core biopsy was collected and the specimens were prepared for histologic and histomorphometric examinations. Results: No adverse effects were seen during healing period. All allograft blocks were well-integrated showing negligible graft resorption. All implants could be placed primary stable. The histological and histomorphometric results showing active bone remodelling, newly formed bone by osteoblasts and active osteoclasts. The newly formed bone was 32 % for patient 2 and 22 % for patient 3 and residual allograft was 17 % and 14 % respectively. Conclusion: Within the limits of the case series cortico-cancellous block allografts undergo active bone remodeling during healing time and allowing primary stable implant placement. Key Words: Human histology, Histomorphometry, Puros, Block allograft, Ridge augmentation.

Introduction Dental implants are widely used in oral reconstruction for the replacement of missing teeth. In many cases pre-implant augmentative surgeries are necessary due to loss of bone volume followed by second stage implant placement. Bone regeneration of minor defects can be done according to the principles of guided bone regeneration (GBR) with different bone graft materials in combination with resorbable or non-resorbable membranes1,2. For vertical and lateral augmentations of the jaw autogenous bone blocks harvested from different intra and extra-oral origins i.e. chin, ramus or iliac crest are widely used to reconstruct the ridge3-5. Despite autogenous bone is considered as the “gold standard”,

* Dr. W. Gutwerk, Ludwigstr. 3, D-63739 Aschaffenburg, Germany. Correspondence: Dr. W. Gutwerk Private Practise Ludwigstr. 3, D-63739 Aschaffenburg, Germany E-mail: [email protected]

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harvesting of autogenous bone brings with several drawbacks. Clinical concerns are donor site morbidity, pain, swelling, bone quality and quantity depending on the donor site as well as graft resorption during healing and increased chair time6-9. For this reasons block grafts of synthetic10,11, xenogenic12,13 and allogenic14-17 origin have been investigated. The most successful results have been obtained with allogenic bone blocks since allogenic bone is similar to autogenous bone and possess a great biological quality18,19. It was shown earlier that performance of autogenous and allogenic onlay grafts is comparable20. Today allogenic block grafts have the advantages of unlimited supply and can be ordered in different packagings and compositions (cancellous or cortico-cancellous blocks). Different kinds of allogenic materials are available depending on origin and processing of the donor material. Going through this fresh-frozen21,22, freeze-dried23,24, mineralized25, demineralized26 and solvent-preserved, gamma sterilized15,17,27 allogenic materials have been investigated for their use in clinical dentistry. The cases that follow present the surgical treatment steps and histological and histomorphometric results

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Table 1 Patient Demographics, Treatment Concept

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Patient

Sex

1

F

Age (years) 53

Defiency narrow ridge regio 11

Healing Time 6.5 months

Biopsy Taken from block

Placed Implants 1

Implant Healing Time 3 months

2

F

63

narrow ridge regio 33-36

6 months

block

2

4 months

3

M

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narrow ridge regio 13-14

6 months

block

3

6 months

after 6 months healing time to reconstruct lower or upper jaw prior to implant placement.

labeled and quantified with analySIS FIVE – software (Soft Imaging System, Münster, Germany) (Table 1).

Methods

Case Report 1

Histology and histomorphometry Specimens were fixed in formaldehyde and dehydrated with an increasing alcohol series. Non-decalcified samples were embedded in Technovit 9100 resin (Heraeus Kulzer, Wehrheim, Germany) after polymerization, specimen cutted in 300 µm sections using a diamond saw (Microslice TM Metals Research, Cambrige, UK). Finally the sections have been grounded to a thickness of approximately 60 µm using a rotating grinding plate (Stuers, Willich, Germany). Non-decalcified specimens were subsequently stained in azure II and pararosaniline (Sigma Aldrich, Steinheim, Germany). Sample imaging was carried out with an Axio Imager M1 microscope equipped with a digital camera AxioCam HRc (Carl Zeiss, Göttingen, Germany). For histomorphometric analysis, the fractions of interest were digitally

A 53 year old non-smoking female patient visited our practice for ridge augmentation of the maxillary anterior region in anticipation of implant placement after augmentation of region 11. Tooth extraction was done by a different practice several months before. Pre-operative X-ray (Fig. 1) shows a lateral and vertical bony deficiency and it was decided to use a corticocancellous block allograft (Puros Allograft Block, Zimmer Dental, Germany) to reconstruct the ridge. Local anesthesia was performed and a full-thickness flap was raised after crestal and vertical incision. The host bone surface was cleaned from soft tissue and decorticated to ensure bleeding and encourage revascularization of the block graft. According to the instructions for use the allograft block was rehydrated with sterile saline solution. To ensure a tight contact between block and host bone the block allograft as

Fig 1 Pre-operative X-ray shows bony defect in region 11.

Fig 2 Well-integrated block after 6.5 months healing time.

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Fig 4  X-ray after implant placement.

Fig 3 implant placed in revascularized bone block, please note the fracture at the buccal aspect. Fig 5  Histological section (original magnification x 50) of the harvested specimen 6.5 months after healing. New bone formation (NB), residual block allograft (P). top = crestal, bottom = apical.

well as the host bone have been shaped with a round bur under cooling. The block was fixed with two screws and sharp edges and corners were removed with a round bur to minimize risk of soft tissue perforation. Gaps between block and host bone were filled with a particulate allograft (Puros® Allograft Cancellous Particles, Zimmer Dental, Germany) with particle size of 0.25-1mm and before closing the flap the augmented area has been covered with a resorbable collagen membrane (CopiOs® Pericardium Membrane, Zimmer

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Dental, Germany). Periosteal releasing incisions were made and the flap was repositioned and sutured without tension with 3-0 suture (Polyester S green, Catgut, Germany). The patient was informed about postsurgical compliance and antibiotics (clindamycin 600 mg, seven days) and oral gargle solution were administered and prescribed. After 10 days soft tissue was healed uneventful and the suture was removed. Healing time of 6.5 months was uneventful. Prior implant placement vertical and crestal incisions were done and a full-thickness flap was raised. The bone block was wellintegrated with slightly resorption at the buccal aspect (Fig. 2). After removing of the bone screws a biopsy was taken from the area were the block was placed. Due to lateral resorption the ridge was expended with osteotoms. While doing this the lateral aspect of the block fractured after implant placement of a Straumann SLA implant 4.1 x 12 mm as shown in Fig. 3. BioOss bone graft (Geistlich, Germany) was used to cover the buccal aspect of the implant and the augmented area was covered with a CopiOs Pericardium Membrane. The flap was closed without tension and sutures were in place for 10 days. Implant was allowed to heal for additional 3 months (Table 1). Fig. 4 presents x-ray after implant placement. The histological analysis in Fig. 5 shows no signs of inflammation after 6.5 months of healing. New bone formation (NB) is clearly visible starting mainly from the surface of the block allograft as well as bone ingrowth stating from the outside of the augmented area is visible (Fig. 5). Mature, lamellar bone could be detected. Some residual fragments

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Fig 6 Residual block allograft (P) bridged by newly formed bone (NB), original magnification x 200.

Fig 7 Resorption of the allograft block (P) in balance with new bone formation (NB), original magnification x 200. Fig 8 Formation of haversian system in not fully remodeled residual allograft, original magnification x 200.

of non-remodelled allograft (P) are still present but are bridged and surrounded by newly formed bone (Fig. 6). Osteocytes are embedded inside the newly formed bone. Balanced remodeling is shown in Fig. 7 were resorption of the block allograft goes along with new bone apposition which indicates osteoblastic and osteoclastic activities. Further new haversion systems are formed in the residual allograft block as seeding point of the bone remodeling (Fig. 8).

Case Report 2 A 63 year old non-smoking female patient presented to our practice with a lateral bone deficiency in the left mandible as shown Fig. 9. The planned treatment concept represents a block grafting with a corticocancellous allograft (Puros Allograft Block) followed by placement of three implants after a healing time of six

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months (Table 1). Local anesthesia was performed and a full-thickness flap was raised after crestal and vertical incision. Preparation of the bone block as well as host bone was carried out as described in case report 1. Finally, three blocks were fixed with five screws (Fig. 10) and space between host bone and allograft block were filled with a particulate bovine bone graft material (BioOss 1 – 2 mm, Geistlich, Germany) and addionally apical of the bone blocks a collagenous sponge material (BioOss collagen, 250 mg, Geistlich, Baden Baden, Germany) was placed to minimize block resorption28. Augmented area was covered with a non-resorbable PTFE membrane (Cytoplast® GBR-200, Osteogenics Biomedical, Inc., USA) and the flap was sutured with 3-0 suture (Polyester S green). The patient was informed about postsurgical compliance and antibiotics (amoxicillin 1.000 mg seven days) and oral gargle solution were prescribed. Post-operative x-ray is shown in Fig. 11. After 9 days suture was removed. Healing time of 6 months was un-

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Fig 9 Bone defect in the mandible of patient 2 (in situ).

Fig 10 Allograft blocks in place and fixed with screws.

Fig 11 X-ray after block augmentation.

Fig 12 X-ray after 6 months of healing time before re-entry and implant placement.

Fig 13 Re-entry after 6 months healing time. Slightly resorption apically at position 35.

eventful. Before Re-Entry a x-ray was taken showing volume stability (Fig. 12). Prior implant placement vertical and crestal incisions were done and a full-thickness flap has been raised. The bone blocks were well-integrat-

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ed with slightly resorption apically of the bone block (Fig. 13). Taking in consideration that Bio-Oss was used to minimize resorption the result is surprisingly because Bio-Oss is a non-resorbable bone graft undergo

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no or only minor osteoclastic resorption29. However bone volume was sufficient to place three implants (2 x Strauman SLA 4.1 x 10mm, 1 x Straumann SLA 4.8 x 10 mm) as shown in Fig. 14. Prior placing the implant at position 34 a biopsy was taken for histological and histomorphometric analysis. Placed implants were covered with a mineralized cancellous allograft (Puros® Allograft Cancellous Particles 1 – 2 mm) and a resorbable collagen membrane (CopiOs® Pericardium Membrane, Zimmer Dental). The flap was repositioned

and sutured with a gore suture (GORE-TEX P5K17 CV-5, W. L. Gore & Associates, Inc. USA) and implants were allowed to heal for additional 4 months (Table 1). Gore suture was removed ten days after implant placement. The histological analysis in Fig. 15 shows no signs of inflammation after 6 months of healing. New bone formation (NB) throughout the complete biopsy is clearly visible starting mainly from the surface of the block allograft (Fig. 15). The allograft is well integrated in newly formed bone. In higher magnificaFig 15  Histological section (original magnification x 50) of the harvested specimen 6 months after healing. New bone formation (NB), residual block allograft (P) and residual Bio-Oss (BO). top = crestal, bottom = apical.

Fig 14 X-ray taken after implant placement. Note the nerv between position 35 and 36.

Fig 16  New bone formation (NB) on and in the allograft block (P), original magnification x 200.

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Fig 17 Osteoblasts (OB) building osteoid (O) followed by lamellar bone formation (NB) on the allograft surface (P), original magnification x 200.

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Fig 18  Fractions of interest digitally labeled. residual block allograft (magenta), new formed bone (red), Bio-Oss (green), original magnification x 50.

tion active bone remodeling is clearly visible showing a continuous resorption of the allograft material by osteoclasts and new bone formation by osteoblasts (Fig. 16, 17). Two slices of the biopsy were digitally labeled (Fig. 18) and amount of new bone formation, residual allograft, Bio-Oss and connective tissue/marrow were calculated in average as 32.2 %, 14.1 %, 14.3

Fig 19 Bone defect buccally.

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% and 39.4 % respectively. The results clearly demonstrate allograft resorption replaced by new formed vital bone.

Case Report 3 A 65 year old non-smoking male referred to our practise with a lateral bone defect in the right maxilla as shown on the x-ray in Fig. 19. The planned treatment concept involved a block grafting with a corticocancellous allograft (Puros Allograft Block) at position 13-14 followed by placement of one implant after a healing time of six months. Further tooth 15 has to be extracted and during the implant surgery at position 13 an lateral sinus lift with simultaneous implant placement at position 15 is planned (Table 1). Local anesthesia was performed and a full-thickness flap was raised after crestal and vertical incision. Preparation of the bone block was carried out as described in case report 1. The host bone was shaped with a piezosurgery device to create an inlay. Finally, the block was fixed with one screw. No second screw was necessary because host bone present mesially and distally of the bone block prevented block rotation and movement. (Fig. 20). Prior covering with a resorbable collagen membrane (CopiOs® Pericardium Membrane) the gaps between block and host bone were filled with mineralized, cancellous allograft particles (Puros® Allograft Cancellous Particles 1-2 mm). The flap was sutured with 3-0 suture (Polyester S green). The patient was informed about postsurgical compliance

Fig 20 Fixed bone block.

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Fig 21  X-ray after block augmentation.

Fig 22 Well-integrated allograft block at position 13-14 and lateral window for sinus lift. Fig 24  Histological section (original magnification x 50) of the harvested specimen 6 months after healing. New bone formation (NB), residual block allograft (P), top = crestal, bottom = apical. Fig 23 X-ray after implant placement.

and antibiotics (clindamycin 600 mg seven days) and oral gargle solution were prescribed. Post-operative x-ray is showing good adaption of the block graft with the recipient bone (Fig. 21). After 10 days soft tissue was healed uneventful and the suture was removed. Healing time of 6 months was uneventful. Prior implant placement vertical and crestal incisions were done and a full-thickness flap was raised. The bone block was well-integrated (Fig. 22) with slightly resorption at the crestal aspect. A biopsy was taken from position 13 followed by implant placement (Straumann SLA 4.1 x 12 mm). A Straumann SLA 4.8 mm x 12 mm was placed at position 15 and sinus lift procedure was done with a bovine grafting material (Bio-Oss®, 1 – 2 mm). The

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implants were covered with the bovine grafting material buccally and a resorbable collagen membrane (CopiOs Pericardium Membrane). The flap was repositioned and sutured with a gore suture (GORE-TEX P5K17 CV-5, W. L. Gore & Associates, Inc. USA) and implants were allowed to heal for additional 6 months (Table 1, Fig. 23). Gore suture was removed ten days after implant placement. The histological analysis in Fig. 24 shows no signs of inflammation after 6 months of healing. New bone formation (NB) throughout the complete biopsy is clearly visible. The residual allograft is well integrated in newly formed bone. In higher magnification active bone remodeling is clearly visible showing new vital bone formation by osteoblasts

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Fig 25 Osteoblasts (OB) building osteoid (O) followed by lamellar bone formation (NB) on the allograft (P) surface, original magnification x 200.

Fig 26 Osteoclastic activitiy (OC) on the allograft surface building a resorption lacunae, original magnification x 200.

(Fig. 25) and osteoclastic resorption on the allograft surface (Fig. 26). The calculated amount of new bone formation, residual allograft, Bio-Oss and connective tissue/marrow were calculated in average of two as 22 %, 17.7 %, 8.9 % and 51.4 % respectively.

All implants have been placed primary stable and survived up to now. Nevertheless adverse events i.e. dehiscences, incision line openings, infections or block failures can occur35. Clinician should be experienced and follow the principles of guided bone regeneration to achieve predictable results.

Discussion Different types of bone grafts are used for reconstruction of the alveolar bone. Allograft block grafting becomes more and more attractive since the results are comparable to autogenous blocks. No second surgery site is required for bone harvesting as a consequence patient morbidity and surgery time are significantly reduced. Published long term results of implants placed in allograft reconstructed jaws have shown survival rates between 93-95%15,23,24,30,31. Within this case study two patients with defects in the maxilla and one patient with mandibular defects have been treated successfully with allograft blocks. The obtained results confirm the effectiveness of cortico-cancellous block allografts. After a healing time of six months active bone remodeling has been proven by histological and histomorphometric analysis. At re-entry the block allograft was fused with the recipient area and has been partially resorbed by osteoclasts while newly formed bone was in close contact with the residual allograft. The histomorphometric results showing new bone formation of 22-32% and are in line with data reported previously32-34. Minimal graft resorption was observed during healing period without negative impact on implant placement.

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Conclusion These case reports demonstrate the success of alveolar ridge reconstruction using cortico-cancellous allograft blocks before implant placement. The histological and histomorphometric analysis clearly demonstrates that used block allograft undergo a continuous remodeling while resorption is driven by osteclastic activity and new bone formation by osteoblastic activity. Therefore block allografts are suitable materials to reconstruct deficiencies of the maxilla or mandible and if no side or adverse effects occur the results are highly predictable.

Acknowledgment The author would like to thank Dr. H. Nagursky, University of Freiburg, Germany for histological and hisomorphometric analysis and Dr. S. Berger, Zimmer Dental. Histologic and histomorphometric analysis was partially funded by Zimmer Dental GmbH, Germany.

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References   1. Aghaloo TL, Moy PK. Which hard tissue augmentation techniques are the most successful in furnishing bony support for implant placement? Int J Oral Maxillofac Implants 2007;22 Suppl:49-70.   2. Wang HL, Carroll MJ. Guided bone regeneration using bone grafts and collagen membranes. Quintessence Int 2001;32:504-515.   3. Cordaro L, Torsello F, Accorsi Ribeiro C, Liberatore M, Mirisola di Torresanto V. Inlay-onlay grafting for three-dimensional reconstruction of the posterior atrophic maxilla with mandibular bone. Int J Oral Maxillofac Surg 2010;39:350-357.   4. Proussaefs P, Lozada J. The use of intraorally harvested autogenous block grafts for vertical alveolar ridge augmentation: a human study. Int J Periodontics Restorative Dent 2005;25:351-363.   5. Schwartz-Arad D, Levin L. Intraoral autogenous block onlay bone grafting for extensive reconstruction of atrophic maxillary alveolar ridges. J Periodontol 2005;76:636-641.   6. Nkenke E, Radespiel-Troger M, Wiltfang J, Schultze-Mosgau S, Winkler G, Neukam FW. Morbidity of harvesting of retromolar bone grafts: a prospective study. Clin Oral Implants Res 2002;13:514-521.   7. Nkenke E, Schultze-Mosgau S, Radespiel-Troger M, Kloss F, Neukam FW. Morbidity of harvesting of chin grafts: a prospective study. Clin Oral Implants Res 2001;12:495-502.   8. Misch CM. Comparison of intraoral donor sites for onlay grafting prior to implant placement. Int J Oral Maxillofac Implants 1997;12:767-776.   9. Raghoebar GM, Meijndert L, Kalk WW, Vissink A. Morbidity of mandibular bone harvesting: a comparative study. Int J Oral Maxillofac Implants 2007;22:359-365. 10. Mertens C, Steveling HG. Use of Synthetic Bone Blocks as an Alternative to Autologous Bone Block Grafts. Implants - international magazine of oral implantology 2009;4. 11. Yamauchi K, Takahashi T, Funaki K, Hamada Y, Yamashita Y. Histological and histomorphometrical comparative study of [beta]-tricalcium phosphate block grafts and periosteal expansion osteogenesis for alveolar bone augmentation. Int J Oral Maxillofac Surg 2010;39:1000-1006. 12. Zecha PJ, Schortinghuis J, van der Wal JE, Nagursky H, van den Broek KC, Sauerbier S, Vissink A, Raghoebar GM. Applicability of equine hydroxyapatite collagen (eHAC) bone blocks for lateral augmentation of the alveolar crest. A histological and histomorphometric analysis in rats. Int J Oral Maxillofac Surg 2011;40:533-542. 13. Schultheiss M, Sarkar M, Arand M, Kramer M, Wilke H-J, Kinzl L, Hartwig E. Solvent-preserved, bovine cancellous bone blocks used for reconstruction of thoracolumbar fractures in minimally invasive spinal surgery—first clinical results. European Spine Journal 2005;14:192-196. 14. Waasdorp J, Reynolds MA. Allogeneic bone onlay grafts for alveolar ridge augmentation: a systematic review. Int J Oral Maxillofac Implants 2010;25:525-531. 15. Keith JD, Petrungaro P, Leonetti JA, Elwell CW, Zeren KJ, Caputo C, Nikitakis NG, Schopf C, Warner MM. Clinical and histologic evaluation of a mineralized block allograft: Results from the developmental period (2001-2004). Int J Periodont Rest 2006;26:321-327. 16. Orsini G, Stacchi C, Visintini E, Di Iorio D, Putignano A, Breschi L, Di Lenarda R. Clinical and histologic evaluation of fresh frozen human bone grafts for horizontal reconstruction of maxillary alveolar ridges. Int J Periodontics Restorative Dent 2011;31:535-544. 17. Morelli T, Neiva R, Wang HL. Human histology of allogeneic block grafts for alveolar ridge augmentation: case report. Int J Periodont Rest 2009;29:649-656. 18. Bianchini MA, Buttendorf AR, Benfatti CAM, Bez LV, Ferreira CF, de Andrade RF. The Use of Freeze-Dried Bone Allograft as an Alternative to Autogenous Bone Graft in the Atrophic Maxilla: A 3-Year Clinical Follow-up. Int J Periodont Rest 2009;29:643-647.

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19. Tudor C, Srour S, Thorwarth M, Stockmann P, Neukam FW, Nkenke E, Schlegel KA, Felszeghy E. Bone regeneration in osseous defects - application of particulated human and bovine materials. Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontology 2008;105:430-436. 20. Maletta JA, Gasser JA, Fonseca RJ, Nelson JA. Comparison of the healing and revascularization of onlayed autologous and lyophilized allogeneic rib grafts to the edentulous maxilla. J Oral Maxillofac Surg 1983;41:487-499. 21. Carinci F, Brunelli G, Zollino I, Franco M, Viscioni A, Rigo L, Guidi R, Strohmenger L. Mandibles Grafted With Fresh-Frozen Bone: An Evaluation of Implant Outcome. Implant Dent 2009;18:86-90. 22. Contar CMM, Sarot JR, da Costa MB, Bordini J, de Lima AAS, Alanis LRA, Trevilatto PC, Machado MAN. Fresh-Frozen Bone Allografts in Maxillary Ridge Augmentation: Histologic Analysis. J Oral Implantol 2011;37:223-231. 23. Nissan J, Ghelfan O, Mardinger O, Calderon S, Chaushu G. Efficacy of Cancellous Block Allograft Augmentation Prior to Implant Placement in the Posterior Atrophic Mandible. Clinical Implant Dentistry and Related Research 2011;13:279-285. 24. Nissan J, Mardinger O, Calderon S, Romanos GE, Chaushu G. Cancellous bone block allografts for the augmentation of the anterior atrophic maxilla. Clinical Implant Dentistry and Related Research 2011;13:104-111. 25. Leonetti JA, Koup R. Localized maxillary ridge augmentation with a block allograft for dental implant placement: case reports. Implant Dent 2003;12:217-226. 26. Schwarz N, Schlag G, Thurnher M, Eschberger J, Zeng L. Decalcified and undecalcified cancellous bone block implants do not heal diaphyseal defects in dogs. Arch Orthop Trauma Surg 1991;111:4750. 27. Keith JD. Localized ridge augmentation with a block allograft followed by secondary implant placement: A case report. Int J Periodont Rest 2004;24:11-17. 28. Maiorana C, Beretta M, Salina S, Santoro F. Reduction of autogenous bone graft resorption by means of bio-oss coverage: a prospective study. Int J Periodontics Restorative Dent 2005;25:19-25. 29. Schlegel AK, Donath K. BIO-OSS (R) - A resorbable bone substitute? Journal of Long-Term Effects of Medical Implants 1998;8:201-209. 30. Novell J, Novell-Costa F, Ivorra C, Fariñas O, Munilla A, Martinez C. Five-Year Results of Implants Inserted Into Freeze-Dried Block Allografts. Implant Dent 2012;21:129-135 110.1097/ ID.1090b1013e31824bf31899f. 31. Franco M, Tropina E, De Santis B, Viscioni A, Rigo L, Guidi R, Carinci F. A 2-year follow-up study on standard length implants inserted into alveolar bone sites augmented with homografts. Stomatologija 2008;10:127-132. 32. Chaushu G, Marilena V, Mardinger O, Nissan J. Histomorphometric analysis following maxillary sinus floor augmentation using cancellous bone-block allograft. J Periodontol 2010;81:1147-1152. 33. Nissan J, Marilena V, Gross O, Mardinger O, Chaushu G. Histomorphometric analysis following augmentation of the posterior mandible using cancellous bone-block allograft. Journal of Biomedical Materials Research Part A 2011;97A:509-513. 34. Nissan J, Marilena V, Gross O, Mardinger O, Chaushu G. Histomorphometric analysis following augmentation of the anterior atrophic maxilla with cancellous bone block allograft. Int J Oral Maxillofac Implants 2012;27:84-89. 35. Chaushu G, Mardinger O, Peleg M, Ghelfan O, Nissan J. Analysis of Complications Following Augmentation With Cancellous Block Allografts. J Periodontol 2010;81:1759-1764.

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The ortho-perio-prosthodontic team-approach for successful management of the single-tooth implant in the esthetic zone Giuseppe Pellitteri*, Ute Schneider-Moser**, Lorenz Moser*** While orthodontic space closure for congenitally missing upper lateral incisors has proven to be a secure treatment approach, orthodontic space opening with subsequent implant substitution remains controversial. The latest developments in bone- and soft-tissue grafting combined with custom-made implant abutments in zirconia have provided the ortho-perio-prosthodontic taskforce with new tools for improving the long-term stability of implant-born crowns in the esthetic zone. An exhaustive knowledge of the latest evidence-based literature and close collaboration between all involved team members from Day I is mandatory for creating a thick periodontal framework which can withstand looming resorptive hard- and soft-tissue processes in the long-term. Keywords: Interdisciplinary treatment, Missing upper lateral incisors, Single-tooth implant, Esthetic zone, Periodontal biotype.

INTRODUCTION Whether it is preferable to close spaces in the anterior maxilla by mesializing the posterior segments with orthodontic appliances or to open the spaces for substitution of congenitally missing laterals by implantborn crowns is an ongoing discussion since the early * MD, Adjunct Professor Department of Dentistry and Maxillofacial Surgery, University of Modena and Reggio Emilia, and in the private practice of orthodontics at 22 Via Mendola, 39100 Bolzano/Italy, e-mail: [email protected]. ** DDS, Adjunct Professor, Department of Orthodontics, University of Ferrara, and in the private practice of orthodontics at 40 Via Alto Adige, Citycenter, 39100 Bolzano/ Italy; e-mail: [email protected]. *** MD, DDS, Adjunct Professor Department of Orthodontics, University of Ferrara, and in the private practive of orthodontics at 40 Via Alto Adige, Citycenter, 39100 Bolzano/Italy, e-mail: [email protected]. Correspondence: Dr. Giuseppe Pellitteri Via Mendola 21 39100 Bolzano E-mail: [email protected]

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times of orthodontics. Older studies have evidenced that patients are less satisfied after space opening and prosthodontic substitution of the missing teeth and that the periodontal conditions are less favourable1-5, while recent articles have emphasized the advantage that overall treatment is finished at a young age and that avoidance of implants leaves the patient with a natural dentition which can adapt to lifelong facial changes.6,7 However, there are situations where space-opening and substitution of the missing lateral incisors is the only treatment option. A Class III malocclusion without surgery, a unilateral agenesis or a generally undersized dentition may call for orthodontic space opening and consecutive insertion of an implant-born crown. In contrast to the orthodontic literature, the periodontal and prosthodontic literature is full of successful and stable long-term results of implant born restorations.8-14 How can the differences between the orthodontic and the perio-prosthodontic literature be explained? Kokich15 and Novackowa et al.16 reported that orthodontic distalization of a canine can generate an osseous crest which provides sufficient support for an implant

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and which remains stable over time. Other studies could not demonstrate the long-term stability of the orthodontically created osseous crest, but revealed significant bone loss and increasing labial concavity of the edentulous site17,18. In our experience, careful and slow orthodontic space opening might generate sufficient osseous width for immediate implantation, but the alveolar ridge will not present a natural looking emergence profile (“bombé”), due to the lack of the characteristic bony bulge over the missing root (Fig. 1,2). Therefore, when the implantologist places the implant more palatally in order to counteract any imminent vestibular bone resorption, the esthetic result will always remain suboptimal. A natural emergence profile and a perfect bombé can only be created by meticulous reconstruction of the hard- and soft-tissue framework. This may not only require a bone graft, but also a connective tissue graft. Close collaboration between the members of the “ortho-perio-prosthodontic” taskforce with exceptional skills and knowledge of the recent evidence-based literature is mandatory to achieve esthetically pleasing and stable results. A tipical tretament sequence for an interdisciplinary patient who requires an implant for a missing lateral incisors, is the following:

1. sufficient mesio-distal orthodontic space opening (6.0-6.2 mm in females and 6.4-6.6 mm in males between the distal contact points of the central incisor and the mesial contact point of the canine);19,20 2. sufficient mesio-distal space opening between the roots of the central and the canine of at least 5.7 mm for a 3.2 mm implant;15 3. a periapical radiograph is performed to check for adequate mesio-distal space and perfect root parallelism.15 Surgical exploration of the implant site: 4. a more palatal insertion of the implant Tapered Screw-Vent (Zimmer Dental, Carlsbad, CA) relative to the adjacent teeth assuring at least 1.2-1.5 mm of covering vestibular bone (Fig. 3); 5. positioning the collar of the implant 2 mm apically of the cementoenamel junction (CEJ) of the adjacent teeth;21,22 6. abundant reconstruction of any osseous defect with Puros (Zimmer Dental, Carlsbad, CA) mineralized human bone matrix or even better “overbuilding” the crest for long-term stability23,24 (Fig. 4); 7. if primary stability permits: Insertion of a provisional crown with a 5mm distance between the contact points and the osseous peaks to complete papillary formation for 3-6 months;25,26

Fig 1 The canines have erupted close to the central incisors.

Fig 2  Although the canines have been slowly distalized depressions in the future implant site are noticeable.

Fig 3 The implant is inserted parallel and more palatally to the alveolus of the tooth to counterbalance future bone resorption.

Fig 4 The vestibulopalatal dimension is augmented with a bone graft to create a natural-looking bony emergence profile over the implant.

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8. if the implant cannot be immediately loaded: Replacement of the orthodontic appliance for 4-6 months. 9. in case of any residual tissue defect: surgical re-entry for a connective tissue graft to create a thicker periodontal biotype and placement of a second provisional crown for another 6 months waiting for completion of tissue maturation;27-30 10. insertion of the definitive customized zirconia abutment and an all-ceramic crown (Fig. 5). Note the complete filling of the preexisting osseous defect and the natural looking emergence profile (Fig. 6). Two patient examples will systematically illustrate how close collaboration between the orthodontist, the implantologist and the prosthodontist can achieve an excellent esthetic prosthetic result and healthy periodontal conditions over time. The key factor for longterm stability seems to be the meticulous reconstruction of the entire periodontal framework, which may not only require a bone graft but also a soft-tissue graft in order to create a resistant thick periodontal biotype.

CASE PRESENTATION 1 The 17-year-old female student presented with a Pseudo-Class III malocclusion with a congenitally missing upper right lateral incisor and a resultant 4mm upper midline deviation to the right and interdental spacing. The upper right canine had spontaneously erupted close to the central incisor. Oral hygiene was unsatisfactory with gingival swelling and bleeding (Fig. 7, 8). The orthodontic treatment plan consisted in space opening for a future implant-supported lateral incisor crown after distalization of the canine and correction of the upper midline deviation (Fig. 9, 10). After complete space opening, a periapical radiograph of the implant site was taken, which revealed excellent root parallelism and a sufficient 6.2 mm interradicular space with preservation of the osseous peaks (Fig. 11). The archwire was temporarily removed and the patient was referred to the implantologist. Clinically, a moderate osseous depression with adequate gingival coverage was evidenced (Fig. 12). In order to achieve a natural-looking emergence profile an implant was inserted more palatally and parallel to the imaginary natural alveolus to avert future bony resorption, and the vestibulopalatal osseous dimension was enFig 5 After 4-6 months of tissue maturation an all-ceramic crown can be cemented.

Fig 6a Insufficient vestibulopalatal bony support immediately after removal of the orthodontic appliances.

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Fig 6b Natural bombé created with an implant and a demineraliuzed human bone graft.

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Fig 7a-c Dentally compensated Class III malocclusion with a congenitally missing upper right lateral incisor. Fig 7d Upper dental midline deviation to the right side.

Fig 8 Panoramic radiograph before treatment.

Fig 9 Sufficient mesio-distal space for implant placement 12 was opened and the upper midline deviation was corrected. Fig 11  The periapical radiograph shows excellent root parallelism and sufficient interradicular space for implant placement.

Fig 10 Symmetrical upper arch form.

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larged by an augmentation with Copios (Zimmer Dental, Carlsbad, CA) mineralized bone covered by a pericardial membrane (Fig. 13, 14). The correct parallel and central implant position was checked with a periapical radiograph (Fig. 15). After 4 months of orthodontic finishing procedures, carefully avoiding any manipulation near the implant site, the appliances were removed (Fig. 16). A lingual 1-1 retainer was bonded in the upper arch and a removable retainer with a resin tooth for substitution of the upper right lateral incisor was handed to the patient. A critical evaluation of the implant site revealed a residual shallow vestibular depression causing an unsatisfactory emergence profile (Fig. 17). It was decided to perform a secondary connective tissue graft over the regenerated vestibular bone covering the implant for enhancing the

“bombé”. Particular attention was given to meticulous matrass suturing with fine ophthalmologic thread for stabilization of the graft and of the coagulum. Immediately after surgery a provisional crown was placed (Fig. 18). 6 weeks after the second surgery, the papillae had practically already fully recovered. The surgical development of the hard and soft-tissue framework had achieved a comparable anatomy to its left counterpart (Fig. 19). After another 4 months the definitive zirconia crown was cemented with an exact 5mm distance between the contact points and the osseous peaks. One year after secondary soft-tissue grafting the papillae have fully recovered and the periodontal conditions appear very stable (Fig. 20). 3 years after surgery the overall situation has remained practically unchanged (Fig 21).

Fig 12 The vestibular bony depression requires bone grafting for achieving a natural bombé.

Fig 13 After a palatally orientated insertion of the implant a vestibular bone graft is performed. Fig 15  The postoperative periapical radiograph reveals a centered implant position with correct distance to the adjacent teeth.

Fig 14  The preexisting bony depression has been completely filled up. Fig 16  Immediately after removal of the orthodontic appliance.

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Fig 17a,b Despite the bone graft a residual depression is present after the 6 months healing period.

Fig 18a,b A connective tissue graft is harvested from the palate and placed over the bone graft to fill up the defect.

Fig 18c,d After meticulous suturing of the flap a provisional resin crown is cemented to allow maturation of the papillae.

Fig 19a,b 6 weeks after grafting the papillae have nearly fully recovered

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Fig 20  Complete maturation of the papillae 12 months after soft-tissue grafting. The anatomy of the implant site appears identical to its left counterpart.

Fig 21 A Excellent overall periodontal stability 3 years after the secondary connective tissue graft.

CASE PRESENTATION 2

placed parallel to the theoretical alveolus of the lateral incisors and close to the palatal cortical bone to counterbalance looming vestibular bone resorption. In order to create sufficient vestibular osseous support and the best possible natural-looking emergence profile over the implant a bone graft was performed. A meticulous suturing technique and immediate placement of provisional crowns respecting the correct 5mm distance between the contact point and the cemento-enamel junction should help tissue maturation and complete filling-in of the developing papillae (Fig. 27). The orthopantomogram revealed a central and parallel implant position (Fig. 28). 8 months after implant insertion, the patient received the final all-ceramic crowns. She was not only very pleased with the esthetic outcome, but reported that her former muscle pain had completely disappeared and that her migraine attacks had become less frequent (Fig. 29, 30, Tab II). 3 years after implant placement the close-up photographs reveal excellent overall periodontal stability with natural-looking emergence profiles over the implants (Fig. 31a-c).

The 20 year old student had already received orthodontic treatment 4 years ago, after which the congenitally missing upper lateral incisors had been substituted with a Maryland bridge. The patient presented with a brachycephalic Class II division 1 skeletal pattern and full Class II occlusal relationships on the right and a ½ Class II occlusion on the left side. Due to a mild dentofacial asymmetry a 2mm lower midline deviation to the right side could be evidenced (Fig. 22, 23, Tab I). The patient reported chronic muscle soreness around her right TMJ and frequent episodes of migraine since her former orthodontic treatment. She was not satisfied at all with the esthetic treatment outcome and willing to undergo a second therapy. The panoramic x-ray revealed insufficient space opening and unparallel inclination of the adjacent central incisors and canines, which made insertion of implant-supported crowns impossible (Fig. 24). As the patient’s major motivation for seeking therapy was a substantial enhancement of both dental and facial esthetics, it was decided to propose a combined orthodontic-orthognathic approach, which included sufficient mesiodistal and parallel space opening for future implants 12 and 22 and a deliberate surgical rotation of the maxillomandibular with bimaxillary surgery for better exposure of the upper anteriors, for lengthening the lower anterior face height and for correction of her facial asymmetry. After 17 months of treatment the appliances were removed. Apart from a solid bilateral Class I occlusion the patient’s esthetics had undergone significant enhancement (Fig. 25). Satisfactory mesio-distal space opening and perfect root parallelism was checked with periapical radiographs (Fig. 26). Two implants were

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DISCUSSION The orthodontic literature is full of upsetting reports and negative assessments of the long-term stability of prosthodontic replacement of congenitally missing upper lateral incisors. This has led to the consensus among many orthodontist that space closure is the first choice leading to “a natural dentition over a long life”.7 But can a dentition which requires six porcelain veneers for optimization of the esthetic result be still considered “natural”?

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Fig 22a,b Frontal and lateral profile pre-treatment.

Fig 22c-g The patient had already undergone orthodontic treatment. She presented with a Class II malocclusion. The congenitally missing upper lateral incisors have been substituted with a Maryland bridge. Fig 23  Pre-treatment lateral headfilm and cephalometric analysis.

Fig 24  The pretreatment panoramic x-ray reveals convergence of the upper canine and and of the central incisor roots.

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Fig 25a-e  A solid bilateral Class I occlusion has been achieved and sufficient mesiodistal spaces have been opened. Note the shallow vestibular depressions which need to be grafted to create a natural-looking bony emergence profile over the future implant.

Fig 27   Two provisional crowns are cemented after careful suturing

Fig 26a,b  The periapical radiographs reveal sufficient mesiodistal space and perfect root parallelism.

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Fig 28  Final panoramic x-ray.

Fig 29a-d  The intraoral situation after the end of treatment. Note that the implants 12 and 22 have been placed palatally to the theoretical alveolus to counterbalance imminent vestibular bone resorption.

Fig 29e,f The patient’s smile and lateral profile after combined orthodontic-orthognathic-implanto-prosthodontic treatment. Surgery by Prof. Mirco Raffaini, Parma/Italy.

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Fig 30   Post-treatment lateral headfilm and cephalometric analysis.

Fig 31a-c  Close-ups 3 years after the end of prosthodontic therapy.

In the last 10 years major advancements both in surgery and in prosthodontics have developed new techniques for achieving great esthetic results of implantborn crowns in healthy periodontal environments. The mere “bone-driven implant placement” has evolved into “restorative-driven implant placement”. Today it is possible to change an unfavorable thin hard- or softtissue framework into a thick and resistant periodontal biotype prior or during implant insertion and by utilizing tooth-colored abutments and all-ceramic crowns the translucency of a natural tooth can be imitated as never before. Our case presentations are backed up by a recent orthodontic controlled study by Manzotti de Marchi et al. who reported that the long-term periodontal status of patients with congenitally missing lateral incisors who had been treated with orthodontic space closure, and those who had undergone space open-

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ing with implant substitution was comparable in the presence of a “thick periodontal biotype” and a minimum 1.5 mm distance between the implant and the roots of the adjacent teeth31. While the orthodontist is responsible for satisfactory mesiodistal and parallel space-opening, the implantologist must enhance the hard- and soft-tissue framework which may require not only bone, but also connective tissue grafting. If these tasks are carefully performed, future studies in the orthodontic literature will be able to reveal more successful long-term outcomes of implant-born restorations for congenitally missing laterals. However, the problem of looming infraocclusion or progressive uprighting of the incisors adjacent to a single-tooth implant cannot be denied and may only be encountered with a good incisor-stability and long-term retention of the achieved orthodontic result.5-7

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Acknowledgments We want to thank for the collaboration the Dental Technicians Marcello Pellitteri and Paolo Smaniotto.

REFERENCES   1. Nordquist GG, Mc Neill RW.:Orthodontics vs. restorative treatmentof the congenitally absent lateral incisor – long-term periodontal and occlusal evaluation. J Periodontol 46:139-43, 1975.   2. Robertson S, Mohlin B.:The congenitally missing upper lateral incisor. A retrospective study of orthodontic space closure versus restorative treatment. Eur J Orthod 22:139-43, 1975.   3. Thilander B. Ödman J, Lekholm U. Orthodontic aspects of the use of oral implants in adolescents: a 10-year follow-up study. Eur J Orthod 23:715-731, 2001.   4. Armbruster PC, Gardiner DM, Whitley JB, Flerra J.:The congenitally missing maxillary lateral incisor Part I. Esthetic judgement of treatment options. World J Orthod 6: 369-375, 2006.   5. Thilander B. Dentoalveolar development in subjects with normal occlusion. A longitudinal study between the ages 5 and 31 years. Eur J Orthod 31:109-20, 2009.   6. Zachrisson BJ, Rosa M, Toreskog S.:Congenitally missing maxillary lateral incisors: Canine substitution. Am J Orthod Dentofac Orthop 139:434-45, 2011.   7. Johal A et al. State of the science on controversial topics: missing maxillary lateral incisors- a report of the Angle Society of Europe 2012 meeting. Progress in Orthodontics 14:20, 2013.   8. Mayer TM, Hawley CE, Gunsolley JC, Feldman S. The single-totth implant: a viable alternative for single tooth replacemnet. J Periodontol 73: 687-93, 2002.   9. Weng D, Jacobson Z, Tarnow D, Hürzeler MB, Faehn O, Sanavi F et al. A prospective multicenter clinical trial of 3i machined-surface implants: results after 6 years of follow-up. Int J Oral Maxillofac Implants 18:41723, 2003. 10. Giannopoulou C, Bernard J-P, Buser D, Carrel A, Belser UC. Effect of intracrevicular restoration margins on peri-implant health: clinical, biochemical, and microbiologic findings around esthetic implants up to 9 years. Int J Oral Maxillofac Implants 18:173-181, 2003. 11. Al-Sabbagh M. Implants in the esthetic zone. Dent Clin N Am 50:391407, 2006. 12. Buser D, Chappuis V, Bornstein MM, Wittneben J-G, Frei M, Belser UC. Long-term stability of contour augmentation with early implant placement following single tooth extraction in the esthetic zone: a prospective, cross-sectiional study in 41 patients with a 5-to 9-year follow-up. J Periodontol 84:1517-1527, 2013. 13. Dorigatti de Avila E, Scaf de Molon R, de Assis Mollo Jr F, Borelli de Barros LA, Capelozza Filho L, de Almeida Cardoso M, Cirelli JA. Multidisciplinary approach for the aesthetic treatment of maxillary lateral incisors agenesis: thinking about implants? Oral Surg Oral Med Oral Pathol Oral Radiol 114:e22-e28, 2012.

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14. Clem DS, Hinds KF.:The team approach to replacing the congenitally missing lateral incisor: restorative and preiodontal considerations. Clin Adv Periodontics 3:106-114,2013. 15. Kokich VG. Maxillary lateral incisor implants: planning with the aid of orthodontics. Int J Oral Maxillofac Surg 62:48-56, 2004. 16. Novackova S, Marek I, Kaminek M. Orthodontic tooth movement: bone formation and its stability in time. Am J Orthod Dentofacial Orthop 139:37-43; 2011 17. Beyer A, Tausche E, Boening K, Harzer W. Orthodontic space opening in patients with congenitally missing lateral incisors. Angle Orthodontist 77(3):404-409,2007. 18. Uribe F, Padala S, Veerasathpurush A, Nanda R. Cone-beam computed tomography evaluation of alveolar ridge width and height changes after orthodontic space opening in patients with congenitally missing maxillary lateral incisors. Am J Orthod Dentofacial Orthop 144(6):848859,2013. 19. Grunder U, Gracis S, Capelli M. Influence of the 3-D bone-to-implant relationship on esthetics. Int J Periodontics Restorative Dent 25: 1139;2005. 20. Misch CE. Contemporary Implant Dentistry. 3rd Edition, Mosby Elsevier,St.Louis:870-904,2008. 21. Kazor CE, Al-Shammari K, Sarment DP, Misch CE, Wang HL. Implant plastic surgery: a review and rationale. J Oral Implantol 30(4):24054,2004. 22. Saadoun AP, LeGall M, Touati B. Selection and ideal tridimensional implant posi- tion for soft tissue aesthetics. Pract Periodontics Aesthet Dent. 11(9):1063-72,1999. 23. Mathews D. Soft tissue management aroound implants in the esthetic zone. Int J Peridontics Restorative Dent 20:141-149,2000. 24. Buser D, Halbritter S, Hart C, Bornstein MM, Grütter L, Chappuis V et al. Early implant placement with simultaneous guided bone regeneration following single-tooth extraction in the esthetic zone: 12-month results of a prospective study with 20 consecutive patients. J Periodontol 80:152-62,2009. 25. Tarnow DP, Cho SC, Wallace SS. The effect of inter-implant distance on the height of the inter-implant bone crest. J Periodontol 71: 546-549, 2000. 26. Gallucci GO, Belser US, Bernard JP, Magne P. Modeling and characterization of the CEJ for optimization of esthetic implant design. Int J Periodontics Restorative Dent 24(1): 19-29;2004. 27. Grunder U. Stability of the mucosal topography around single-tooth implants and adjacent teeth: 1-year results. Int J Periodontics Restorative Dent 20:11-17, 2000. 28. Covani U, Marconcini S, Galassini G, Cornelini R, Santini S, Barone A. Connective tissue graft used as a biologic barrier to cover an immediate implant. J Periodontol 78(8): 1644-9; 2007. 29. Palacci P, Nowzari H. Soft tissue enhancement around dental implants. Periodontology 2000 47:113-132,2008. 30. Lee Y-M, Kim JY, Koo K-T. Peri-implant soft tissue level secondary to a connective tissue graft in conjucntion with immediate implant placement: a 2-year follw-up report of 11 consecutive cases. The Int J Periodontics Restorative Dent 32(2), 213-22; 2012. 31. Manzotti De Marchi L. et al. Congenitally Missing Maxillary Lateral Incisors: Functional and Periodontal Aspects in Patients Treated with Implants or Space Closure and Tooth Re-Contouring, Open Dent J. 2012; 6: 248–254.

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Preliminary outcome in consecutively treated case series with Trabecular Metal implants Carlo Maria Soardi*, Hom-Lay Wang**, Emanuele Clozza***, Davide Zaffe****, Luigi Checchi***** Objective: The aim of this study was to illustrate the successful use of Trabecular Metal (TM) implants placed in posterior maxilla following maxillary sinus augmentation. Methods and Materials: Twelve TM implants were placed after maxillary sinus augmentation using mineralized human bone allograft (MHBA) in 6 patients. At second stage procedure, 3 months after TM implants installation, the outcome measures evaluated were implant success and removal torque test. Result: At second stage procedure, the implant success rate was 100%. No evidence of peri-implant marginal bone loss was noted clinically and all implants successfully tolerated a 25 Ncm torque test. Conclusioni: The favorable outcome of the treatment described suggests that the rehabilitation of atrophic posterior maxillary region can be achieved by the placement of TM implants in sites augmented with MHBA. Key Words: Allograft, Bone regeneration, Sinus floor augmentation, Tantalum, Implants 3.

Introduction The use of human bone for the regeneration of osseous defects has significantly changed implant dentistry in the past 20 years1. Autologous bone has been considered the material of choice for bone grafting procedurs because it possesses osteoconductive, os* Private Practice, Brescia, Italy. **  DDS, MSD, PhD, Professor and Director of Graduate Periodontics, Department of Periodontics and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, MI, USA. *** Resident, Department of Periodontology and Implant Dentistry, New York University College of Dentistry, New York, NY, USA. **** PhD, ScMBiol, Associate Professor, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Italy. ***** Professor and Chairman of Periodontology and Orthodontics, Department of Periodontology and Implantology, University of Bologna, Bologna, Italy. Correspondence: Emanuele Clozza New York University College of Dentistry Ashman Department of Periodontology and Implant Dentistry 345 East 24th Street, Suite 3W, New York, NY 10010, USA Telephone Number: +1(212)992-7040 FAX Number: +1(212)995-3961 E-mail: [email protected]

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teoinductive, osteogenic and properties2. However, the harvesting of bone from patients presents many disadvantages, including morbidity of the donor site and high risk of severe complications3. Moreover, the supply of autologous bone graft may be limited3. As a consequence, alternative grafting materials resembling the properties shown by autologous bone were devoloped and favorable outcomes were reported by systematic reviews in terms of the survival rate of implants placed into augmented maxillary sinuses4,5. Recent advancements have led to the development a new Trabecular Metal (TM) implant (Zimmer Dental Inc., Carlsbad, CA.) in tantalum. Tantalum possesses characteristics that confer significant advantages over traditional implant materials: it is chemically stable and biocompatible, and can be manufactured with a threedimensional architecture similar to that of bone trabeculae6. In addition, it presents favorable strength even in its trabecular form6. Pre-clinical and clinical studies have reported that bone ingrowth occured into the trabecular bone holes7-10. Remarkably, the use of tantalum in orthopedics is recommended in regions where the bone quality is questionable11,12. Shifting this paradigm from orthopedics to implant dentistry, the use of TM implant should be considered

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a feasible treatment approach in augmented sites and succeessfully loaded in the early phase of maturation, where the bone quality might not resemble the characteristics of native bone. Therefore, the aim of this preliminary report was to illustrate that TM implants can be successfully employed for the rehabilitation of edentulous posterior maxilla after maxillary sinus augmentation with mineralized human bone allograft (MHBA).

Materials and Methods Study design Six patients (5 females and 1 male, between 35 and 71 years of age) were selected from a pool of subjects requiring maxillary sinus augmentation for the placement of delayed posterior implants (Table 1). All patients were partially or totally edentulous and in need of unilateral maxillary sinus augmentation. The recruitment and active treatment period was February 2011 to January 2013 and carried out by the same operator (C.M.S) in a private dental office in Brescia, Italy. Patients were systemically healthy; they did not neither smoke and nor take any medications. Clinical examinations, panoramic radiographs and cone beam computed tomographies (CBCTs) scan were used for pre-operative evaluation (Fig 1a). Patients agreed to the intervention and signed a written consent form, according to the Helsinki protocols.

Surgical procedures Maxillary sinus augmentation and post-operative care was performed transcrestally (Figs 2a and 2b), as described in previous publications13. Monthly followup was scheduled to check the wound healing up to implant insertion. A CBCT scan was taken 6 months after sinus augmentation (Fig 1b). The 3D radiographic examination revealed the presence of an adequate amount of bone in all the regenerated sites, thus allowing a proper prosthetically driven implant planning. At the time of implant installation (6 to 11 months after sinus augmentation) a significant amount of newly formed bone gain was noted clinically in all the implant sites. A surgical guide was fabricated to dictate the position of initial osteotomy. Next, a trephine drill (external diameter of 4 mm; internal diameter of 3 mm; Stroma GmbH, Emmingen-Liptingen, Germany) was utilized to collect bone cores at 600 rpm under a saline jet prior implant insertion. The implant platform was positioned at the same level of the bone crest. A total of 12 TM fixtures were placed (Fig. 6d and Table 1). Flaps were repositioned and secured with single interrupted sutures (Gore-Tex 5.0, W. L. Gore & Associates, Flagstaff, AZ) to achieve primary closure. A second-stage procedure was performed three months later to uncover the fixtures (Figs 3a and 3b). The reverse torque testing (Implantmed, W & H, Bürmoos, Austria) at 25 Ncm (Fig 3c) confirmed the osseointegration implants. Healing abutments were attached to the implants (Figs 3d and 3e). Finally, the rehabilitation on

Fig 1 (a) Preoperative CBCT. (b) Six months after sinus augmentation. c) CBCT taken immediately after implant placement.

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implants (Fig 3f) was finalized as described in Table 1. The criteria for implant success were chosen according to Albrektsson et al.14 and included: absence of implant mobility, absence of peri-implant radiolucency, absence of persistent subjective complaints (dysesthesia, foreign body sensation and pain) and absence of peri-implant infection with suppuration. Histologic preparation Bone core biopsies were fixed, embedded in polymethyl methacrylate (PMMA) and sectioned as described by Soardi et al.15 Microradiographs, toluidine blue or trichrome Gomori staining of 5-μm-thick sec-

tions, photographs, and bone and graft amount evaluations were performed as previously reported15.

Results Clinical results Primary wound closure was obtained in all surgeries and no complaint or adverse effects were observed during the follow-up. All the 12 implants healed submerged without exposure. All the implants were integrated, retained and functional up to the time of the

Table 1 Demography, implant site and sizes, timing of implant procedures and type of prosthesis delivered Patient No.

Age (years)

Sex

Implant site

1

35

F

27

2

51

F

3

45

F

4

62

M

Implant diameter (mm) 4.7

Implant length (mm) 11.5

Timing (months) Implant Stage-two positioning surgery 10 3

CC

26

6

11.5

24

4.1

11.5

FSPD

16

4.7

11.5

FSPD

14

4.1

11.5

16

4.7

11.5

26

4.7

11.5

16

4.7

11.5

6

Prosthesis delivered

3

FSPD

FSPD 8

3

11

3

CC CC CC

5

71

F

16

4.7

11.5

7

3

CC

6

68

F

14

4.1

11.5

6

3

FSPD

16

4.7

11.5

FSPD

26

4.7

11.5

FSPD

24

4.1

11.5

FSPD

Fig 2 (a) Crestal window approach. (b) Sinus augmentation with MHBA particles. (c) Placement of two TM implants. d) The implant platform was positioned at the same level of the bone crest.

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Fig 3 (a) Second stage procedure. (b) Removal of the Cover screw. (c) Reverse torque testing performed at 25Ncm. (d) Placement of the healing abutment. (e) Flap sutured. (f) Cementation of zirconia abutments.

completion of this manuscript. At second stage procedure, no evidence of peri-implant marginal bone loss was noted clinically and all implants successfully tolerated a 25 Ncm torque test. Histologic results Six to eleven months after grafting, biopsies showed the presence of newly formed trabecular bone were in intimate contact with residual allograft particles. Limited presence of pristine bone was found in all samples. The histomorphometric evaluation of the amount of vital bone per tissue volume of all biopsies ranged from 17.8% to 25.3%.

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Discussion This descriptive study illustrated that TM implants could be successfully employed to rehabilitate posterior maxilla previously augmented by allografts. The crestal approach was chosen to enter the sinus cavity as this technique according to a preliminary report13 seemed to minimize dramatically the rate of implant failure. The histologic analysis revealed that the TM were placed in amost purely augmented bone. The amount of newly formed bone reported in the present study was almost similar to that described by Soadi et al.15.

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At second stage procedure, all 12 TM implants fulfilled the criteria for implant success introduced by Albrektsson et al.14, thus highlighting the positive performance of these implants whether placed in bone of questionable quality. A number of devices and techniques have been developed to assess primary and secondary stability16. In the present study, we verified the osteointegration of TM implants using the reverse torque test. This method is based on unscrewing (the opposite of cutting torque) the implant from bone by the application of a counterclockwise torque up to 20 Ncm at second-stage surgery17. While osseointegrated implants will resist a reverse torque at this level, osseointegration failure with fibrous encapsulation will lead to an unscrewing18. We demonstrated that all 12 implants successfully withstand the 25 Ncm reverse torque test three months after implant placement. A higher value of rotational force was applied in our protocol, as we argued the TM implant configuration could have yielded additional resistance to reversal rotational force, given that bone ingrowth into the midsection of the implant. This phenomenon was and also extensively documented in orthopedic literature6,7.

Conclusions Based on the favorable results gathered by this clinical study, we propose that the rehabilitation of atrophic posterior maxillary region can be achieved by the placement of TM implants in sites augmented with MHBA. The conclusions drawn from this case series need to be verified in more rigorously designed studies.

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References   1. Buser D. Preface. In: Buser D. 20 Years of guided bone regeneration in implant dentistry, 2nd edition. Hanover Park: Quintessence Publishing;2009:viii.   2. Laurencin C, Khan Y, El-Amin,SF. Bone graft substitutes. Expert Review of Medical Devices 2006;3:49–57.   3. Reissmann DR, Dietze B, Vogeler M, Schmelzeisen R, Heydecke G. Impact of donor site for bone graft harvesting for dental implants on health-related and oral health-related quality of life. Clin Oral Implants Res 2012. doi: 10.1111/j.1600-0501.2012.02464.x.   4. Wallace SS, Froum SJ. Effect of maxillary sinus augmentation on the survival of endosseous dental implants. A systematic review. Ann Periodontol 2003; 8:328–343.   5. Del Fabbro M, Testori T, Francetti L, Weinstein R. Systematic review of survival rates for implants placed in the grafted maxillary sinus. Int J Periodontics Restorative Dent 2004; 24:565-577.   6. Smith JO, Sengers BG, Aarvold A, Tayton ER, Dunlop DG, Oreffo RO. Tantalum Trabecular Metal - addition of human skeletal cells to enhance bone implant interface strength and clinical application. J Tissue Eng Regen Med 2012 Jun 4. doi: 10.1002/term.1525.   7. Bobyn JD, Stackpool GJ, Hacking SA, Tanzer M, Krygier JJ. Characteristics of bone ingrowth and interface mechanics of a new porous tantalum biomaterial. J Bone Joint Surg Br 1999;81:907-914.   8. Welldon KJ, Atkins GJ, Howie DW, Findlay DM. Primary human osteoblasts grow into porous tantalum and maintain an osteoblastic phenotype. J Biomed Mater Res A 2008;84:691-701.   9. Unger AS, Lewis RJ, Gruen T. Evaluation of a porous tantalum uncemented acetabular cup in revision total hip arthroplasty. Clinical and radiological results of 60 hips. J Arthroplasty 2005;20:10021009. 10. Black J. Biological performance of tantalum. Clin Mater 1994;16:167173. 11. Tsao AK, Roberson JR, Christie MJ, Dore DD, Heck DA, Robertson DD, Poggie RA. Biomechanical and clinical evaluations of a porous tantalum implant for the treatment of early-stage osteonecrosis. J Bone Joint Surg Am. 2005;87 Suppl 2:22-7. 12. Shuler MS, Rooks MD, Roberson JR. Porous tantalum implant in early osteonecrosis of the hip: preliminary report on operative, survival, and outcomes results. J Arthroplasty. 2007 Jan;22(1):26-31. 13. Soardi CM Wang H-L. New crestal approach for lifting sinus in the extremely atrophic upper maxillae. Clin Adv Periodontics 2012;3:179-185. 14. Albrektsson T, Zarb G, Worthington P, Eriksson AR. The long-term efficacy of currently used dental implants: A review and proposed criteria of success. Int J Oral Maxillofac Implants 1986;1:11–25. 15. Soardi CM, Spinato S, Zaffe D Wang H-L. Atrophic maxillary floor augmentation by mineralized human bone allograft in sinuses of different size: an histologic and histomorphometric analysis. Clin Oral Impl Res 2011;22:560–566. 16. Çehreli MC, Karasoy D, Akca K, Eckert SE (2009). Meta-analysis of methods used to assess implant stability. Int J Oral Maxillofac Implants 24:1015. 17. Sullivan DY, Sherwood RL, Collins TA, Krogh PH (1996). The reverse-torque test: a clinical report. Int J Oral Maxillofac Implants 11:179–185. 18. Hämmerle CH, Glauser R (2004). Clinical evaluation of dental implant treatment. Periodontol. 2000 34:230–239. 19. Brånemark R. Biomechanical study of Göteborg:University of Göteborg,1996.Osseointegration.

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Surgery All at Once™: Socket preservation and immediate placement of an implant in an infected site in the anterior region – a Case Report W.P. van der Schoor*, A.R.M. van der Schoor* Tooth extraction followed by socket preservation and immediate placement of an implant in the esthetic zone are now a part of everyday clinical practice. The following case illustrates this technique with a Trabecular Metal™ Dental Implant (Zimmer Dental Inc., Carlsbad,CA) immediately placed in an infected site in the maxillary anterior accompanied by guided bone regeneration with a combination with allogenic (Puros® Cortical Particulate Allograft, Zimmer Dental Inc.) and autogenous bone. Keywords: Alveolar Ridge Augmentation, Immediate Implant, Immediate Restoration.

Introduction The traditional implantology of the 1980s has given rise to modern techniques that focus on shortening surgical times, limiting costs, and providing immediate esthetics. Numerous studies have reported that survival rates of dental implants immediately placed in tooth extraction sockets were similar to delayed implantation in healed extraction sites.1,2 The increasing importance of immediate esthetics has made the irreversible loss of a tooth in the anterior jaw something that needs to be solved as quickly, conveniently and esthetically as possible for our patients. * DDS, Private Practice, Garderen, The Netherlands. Correspondence: W.P. van der schoor Paleisweg 5 - 3886LC Garderen The Netherlands E-mail: [email protected]

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The extraction of a tooth in the anterior jaw, followed by approximately six to eight months3 of waiting before implant placement, then subsequent rehabilitation of the implant three to six months1 later can have a significant anatomical effect on the area due to the inevitable remodeling of hard and soft tissues,4,5 as well as a psychological effect on the patient. The combination of a socket preservation technique with immediate placement of an implant might help to limit, resorption of the buccal wall.6 Resorption7-9 The use of a Trabecular Metal™ monoblock acetabular component with a partial purous tantalum surface has been shown to have the potential to bridge gaps between bone and the implant surface of 5 mm or less in orthopedic applications,4 but this has never been demonstrated with Trabecular Metal™ dental implants (Zimmer Dental Inc.) placed in human jaws.

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S c h o o r W P,

va n d e r

S c h o o r ARM

Materials and Methods A 42-year old woman with no relevant disease history or known allergies presented with recent loss of the maxillary lateral right incisor and a periapical lesion on the maxillary right central incisor (Fig 1). A post-and-crown restoration served for more than 10 years without detectable endodontic treatment. The patient had no complaints about the esthetics of her dentition, despite the pronounced difference in gingival outline between the right and left central incisors (Fig 2). After discussing the case and alternative treatment options, the patient chose to have a fixed 2-unit bridge supported by 1 implant placed in the right central incisor location, and a cantilevered pontic to replace the left central incisor.

The treatment plan included the option of immediate or delayed implant placement following extraction of the central incisor, provided primary fixation could be achieved in the prestine apical bone. After extraction of the central incisors and thorough debridement of the sockets, the right socket would be sequentially enlarged to receive an implant. If that were not possible due to an inadequate volume of available bone, then a socket preservation technique would be performed, followed by delayed implant placement 3 months later. Antibiotic prophylaxis with clamoxyl 3gr, 1 hour prior to surgery and 750mg every 8 hours seven days after surgery and chlorhexidine mouthwash five days prior at two rinses per day were prescribed up to 1 week after surgery. Only on the first 2 days after surgery instead of chlorhexidine mouthwash, a warm water salt-solution was prescribed.

Fig 1 Panoramique pré-opératoire.

Fig 2 Pre-op situation.

Fig 3 Extracted tooth # 8.

Fig 4 Unprepared alveolus.

Fig 5 Esthetic Buccal flap: periapical lesion.

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va n d e r

•

• • • •

The following surgical procedure was used: Anesthesia via infiltration with 4% articaine containing 1:100 adrenaline in the vestibular and palatine front areas. Extraction of the root (Fig 3). Curettage of the socket and bone integrity assessment of the cervical buccal plate (Fig 4). Buccal esthetic flap incision5 to access a fenestration in the apical area (Fig 5). After thorough debridement of the apical area, initial drilling was performed with a 3,2 Ø mm bone collecting/crushing trephine drill to uncover pristine palatal/apical bone a in the site (Fig 6).

Fig 6 Initial drill: Trephine collecting drill.

S c h o o r W P,

va n d e r

S c h o o r AR M

• F inal preperation was performed with a final Ø 3,8 mm drill (Figs 8-10). • A bone pusher from a osteome set (Figs 11-12) was used to guide placement of Puros® Cortical Particulate Allograft (Zimmer Dental Inc.) along the shank into the socket, thus creating a canal for the final placement of the implant (Figs 13-15). • After condensing the particulate allograft, the bone pusher was gently withdrawn (Fig 16). • The collected, crushed autogenous bone was returned into the canal before inserting the Trabecular Metal™ Implant (Zimmer Dental Inc.) (Figs 17-19).

Fig 7 Collected bone inside drill.

Fig 8,9 First preparation after trphine collecting drill.

Fig 10,11 Final drill preparation.

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Fig 12 Boneconden- Fig 13,14 input Puros® particulate cor- Fig 15 Gentle resor as spaceholder tical bone. moval placeholder. in position.

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• A  fter placement, the emergence profile of the implant was not parallel with the adjacent dentition, and initial stability of the implant could not be determined tactilly. A surgical screwdriver handle was used to press the implant mesially into a more appropiate position, and then was used to slightly tap in the implant to try to accomplish a higher primary stability (Figs 20-23). • After placement of a healing abutment, the soft tissue gap was filled in with a compressed collagen plug (Collapug®, Zimmer Dental Inc.). A retainer (Essix®,Dentsply, York, PA) served as a provisional prosthesis (Figs 24-27).

• H  ealing was uneventful after 7 days (Fig 28). • Healing was unremarkable after 3 months (Fig 29). Soft and hard tissues healed uneventfully without signs of excessive resorption. • The final restoration was delivered 3 months after surgery (Figs 30-31).

Fig 16 Gentle removal placeholder.

Fig 17 Excess of Puros®.

Fig 18,19  Return autogenous bone Fig 20,21  Insertion Trabecular Metal Fig 22,23  Correction angulation iminside preparation. Implant. plant.

Fig 24 Implant in position, Note trabecular midsection.

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Fig 25 Healingcollar screwed in position, surrounded with compressed collagen CollaPlug.

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Fig 26 Primary closing.

Fig 27 Temporay essix-retainer.

Fig 28  Healing after 2 weeks. Note mucosal ingrowth transformed Collaplug.

Fig 29 Healing after 8 weeks.

va n d e r

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Fig 30 Final restoration after 3 months.

Fig 31 RadiographFinal restoration after 3 months.

Results After treatment, optimal mesial and distal marginal bone stability was observed from the time of the surgery until the three-month post-loading check-up, without apparent remodeling. In regard to the soft

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tissues, from the surgery to placement of the final prosthesis, no recession occured. Preoperative (Fig 2) and post-treatment (Fig 31) images showed a slight improvement. The final esthetic and functional results fulfilled the patient’s expectations.

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Discussion

References

The whole treatment took only 3 months. Since it was impossible to create adequate initial stability, immediate loading of the implant was not indicated. The application of pressing and some tapping to bring the implant into a favorable position for a good prosthetic result did not appear detrimental in the present case. The 13mm Trabecular Metal™ implant (Zimmer Dental Inc.) was the longest implant length available at the time of placement. Perhaps placement of a longer (16 mm) implant might have achieved adequate primary stability for immediate loading. Puros® Cortical Particulate Allograft (Zimmer Dental Inc.) was selected because it was felt that its resorption rate, which is slower than than cancellous particulate, might provide the healing site with a longer period of support.

  1. Annibali S. et al. Immediate, early, and late implant placement in first-molar sites: a retrospective case series. Int J Oral Maxillofac Implants, 2011;26(5):1108-22.   2. Lang NP et al. A systematic review on survival and success rates of implants placed immediately into fresh extraction sockets after at least 1 year. Clin Oral Implants Res, 2012;23(Suppl. 5):39-66.   3. Brånemark P-I, Hansson BO, Adell R, Breine U, Lindström J, Hallén O, Ohman A. Osseointegrated implants in the treatment of the edentulous jaw. Experience from a 10-year period. Scand J Plast Reconstr Surg Suppl. 1977;16:1-132.   4. Marconcini S et al. Immediate implant placement in infected sites: a case series. J Periodontol, 2013;84(2):196-202.   5. Minichetti JC, D’Amore JC, Hong AY. Three-year analysis of tapered screw vent implants placed into maxillary sinuses grafted with mineralized bone allograft. J Oral Implantol, 2008;34(3):135-41.   6. Fugazzotto PA. Treatment options following single-rooted tooth removal: a literature review and proposed hierarchy of treatment selection. J Periodontol, 2005;76(5):821-31.   7. Lang LA et al. Immediate Restoration of Single Tapered Implants with Nonoccluding Provisional Crowns: A 5-Year Clinical Prospective Study. Clin Implant Dent Relat Res, 2012: p. n/a-n/a.   8. Macheras GA et al. Radiological evaluation of the metal-bone interface of a porous tantalum monoblock acetabular component. J Bone Joint Surg Br, 2006;88(3):304-9.   9. Steigmann M, Wang HL. Esthetic buccal flap for correction of buccal fenestration defects during flapless immediate implant surgery. J Periodontol, 2006;77(3):517-22.

Conclusions The combination of socket preservation with Puros® Cortical Particulate Allograft (Zimmer Dental Inc.) and a Trabecular Metal™ implant (Zimmer Dental Inc.) resulted in almost complete maintenance of the hard and soft tissues 3 months after treatment.

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VOLUME 30  •  NUMBER 2bis  •  2014