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THE American JOURNAL OF

DENTISTRY

VOL UME

1

FA L L

N UMB E R 2 0 1 1

1

The American Journal of Esthetic Dentistry

Volume 1  •  Number 1

Fall  •  2011 (1–84)

The American Journal of

DENTISTRY

Volume 1  •  Number 1  •  Fall 2011

ISSN 2162-2833 (print) ISSN 2162-2841 (online)

 5

Editorial: Welcome aboard!

Richard J. Simonsen

10

Minimally Invasive Restorative Treatment of Hypoplastic Enamel in Anterior Teeth

Jussara Karina Bernardon

The Gray Zone Around Dental Implants: Keys to Esthetic Success

Iñaki Gamborena

Determining the Influence of Flowable Composite Resin Application on Cuspal Deflection Using a Computerized Modification of the Strain Gauge Method

Hamdi H. Hamama

26

48

60

 7  8

All-Ceramic Crowns and Extended Veneers in Anterior Dentition: A Case Report with Critical Discussion

Renata Gondo Luiz Narciso Baratieri

Markus B. Blatz

Nadia M. Zaghloul Ossama B. Abouelatta Abeer E. El-Embaby

Júnio S. Almeida e Silva Juliana Nunes Rolla Daniel Edelhoff Élito Araujo Luiz Narciso Baratieri

Guidelines for Authors Mandatory Submission Form

Readers are invited to submit personal photographs for consideration for use in the journal. The number of photos may vary in each issue, but we hope the images will provide an interesting break between the outstanding papers within. This is an opportunity for you, the reader, to share with your colleagues some of the images you are proud of, that may otherwise never see the light of day. For this inaugural issue, we present images from Antelope Canyon, a slot canyon in northern Arizona, photographed by Richard J. Simonsen (http://www.richardsimonsen.com). At certain times of the year and day, the sun may shine through from the slot above that communicates to the surface. Such canyons can be dangerous, as they fill with rainwater quickly in the event of a thunderstorm upstream, sometimes trapping those who choose to ignore nature’s warnings. It is the effect of the running water over millions of years that makes the unique patterns on the walls of the soft sandstone rock walls.

The American Journal of

Publisher

H. W. Haase Executive Vice President

William G. Hartman

Director, Journal Publications

DENTISTRY

Lori A. Bateman

Managing Editor ISSN 2162-2833 (print) ISSN 2162-2841 (online)

Colleen E. O’Keefe Production Manager

Diane J. Curran

Director, Advertising Sales

Editor-in-Chief Richard J. Simonsen, DDS, MS Professor, Faculty of Dentistry Health Sciences Center Kuwait University PO Box 24923, Safat 13110, Kuwait [email protected]

Editorial Board

Joel H. Berg, DDS, MS Markus B. Blatz, DMD, PhD Jeff Brucia, DDS John R. Calamia, DMD Alexander Carroll, DDS, MBA David Chambers, EdM, MBA, PhD Gordon J. Christensen, DDS, MSD, PhD Theodore P. Croll, DDS Alessandro Devigus, Dr Med Dent Sillas Duarte Jr, DDS, MS, PhD Newton Fahl Jr, DDS, MS Jack L. Ferracane, PhD Ronald E. Goldstein, DDS Laura C. Kottemann, DMD Gerard Kugel, DMD, MS, PhD Tyler Lasseigne, DDS Pascal Magne, Dr Med Dent, PhD Tidu Mankoo, BDS Assad F. Mora, DDS, MSD Marc L. Nevins, DMD, MMSc Vijay Parashar, DDS, MS André V. Ritter, DDS, MS Richard D. Roblee, DDS, MS David D. Rolf II, DMD, MS

William G. Hartman

Editorial, Advertising, and Subscriptions Quintessence Publishing Co, Inc 4350 Chandler Drive, Hanover Park, IL 60133 Tel: (630) 736-3600. Fax: (630) 736-3633 Toll-free (US/Canada): (800) 621-0387 E-mail: [email protected] Introductory subscription rate (Vols 1 and 2, six issues; includes online version): Regular rate for North America is $248; $430 institutional. International rate (outside North America) is $278 regular; $460 institutional. International subscribers add $30 to international rate for air mail. Special student rate is $150 ($180 international); verification of student status required on submission of subscription order. AJED is published quarterly by Quintessence Publishing Co, Inc. Postmaster: Send address changes to Quintessence Publishing Co, Inc, 4350 Chandler Drive, Hanover Park, IL 60133, USA. Copyright © 2011 by Quintessence Publishing Co, Inc. All rights reserved. Printed in Germany. No part of this journal may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information and retrieval system, without permission in writing from the publisher. The publisher and editors assume no responsibility for unsolicited manuscripts. The views expressed herein are those of the individual authors and are not necessarily those of the publisher. Information included herein is not professional advice and is not intended to replace the judgment of a practitioner with respect to particular patients, procedures, or practices. To the extent permissible under applicable laws, the publisher disclaims responsibility for any injury and/or damage to persons or property as a result of any actual or alleged libelous statements, infringement of intellectual property or other proprietary or privacy rights, or from the use or operation of any ideas, instructions, procedures, products, or methods contained in the material herein. Permission to photocopy items solely for internal or personal use, and for the internal and personal use of specific clients, is granted by Quintessence Publishing Co, Inc, for libraries and other users registered with the Copyright Clearance Center (CCC) Transaction Reporting Service, provided that the base fee of $5 per article plus $.10 per page is paid directly to CCC, 222 Rosewood Drive, Danvers, MA 01923 (www. copyright.com). Identify this publication by including the fee code: 2162-2833/11 $5 + $.10.

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Printed in USA.

Leo E. Rouse, DDS Frank Spear, DDS, MSD Douglas A. Terry, DDS

Editorial

Welcome aboard!

I

am very pleased to welcome you to a new addition to Quintessence Publishing Company’s stable of fine

journals and books in dentistry. This is the first issue of The American Journal of Esthetic Dentistry, a journal dedicated to promoting the highest clinical standards of esthetic dentistry based on an evidence base and on a minimally invasive approach. We wish to share with our readers the research advances and clinical accomplishments of the profession over the past several decades. With our outstanding editorial board

readers. I may take a certain position

and many others who will aid in the re-

on an issue in order to stimulate con-

view of papers and ideas for the journal,

versation and responses such that a

we pledge to provide you with the high-

broad perspective of opinions can be

est standard of peer-reviewed informa-

aired. It will be my job as your editor to

tion in the form of papers submitted by

try to stimulate such debates and com-

you, the reader, and fellow dedicated

mentary, such as, for example, around

members of our profession.

the current overtreatment problems

The theme of “esthetic dentistry” is a

in the cosmetic dentistry arena. I also

broad one. One could argue that almost

welcome guest editorials from those of

all phases of clinical dentistry involve—

you who may wish to tackle a particular

directly or indirectly—esthetics, and we

subject of interest to the profession. An

will publish papers in most areas of

active and robust “Letters to the Editor”

clinical interest to the general dentist,

section is on my list of goals for devel-

who is faced with the enormous task of

opment as time goes on. I hope that

keeping up with new developments in

you will feel free to communicate with

all fields of the profession. You can ex-

me on any ideas or constructive criti-

pect many papers of the quality you

cism you may have.

see here in this issue from around the

Please enjoy the first issue of The

globe, and also you can expect excit-

American Journal of Esthetic Dentistry !

ing new developments in terms of being able to review your journal and read the papers online with your iPad or similar instrument in months to come. Future editorials will discuss themes and trends in our profession that I hope

Richard J. Simonsen, DDS, MS

will be of interest to a wide group of

Editor-in-Chief

5 VOLUME 1 • NUMBER 1 • FALL 2011

The American Journal of

DENTISTRY Guidelines For Authors Manuscript Submission Submit manuscripts via AJED’s online submission service: www.manuscriptmanager.com/ajed Manuscripts should be uploaded as a PC Word (doc) file with tables and figures preferably embedded at the end of the document. No paper version is required. Manuscript Preparation The Journal will follow as much as possible the recommendations of the International Committee of Medical Journal Editors (Vancouver Group) in regard to preparation of manuscripts and authorship (Uniform Requirements for Manuscripts Submitted to Biomedical Journals, updated October 2008; www.icmje.org). Manuscripts should be typed doublespaced with a 1-inch margin all around. Number all pages. Do not include author names as headers or footers. The first page must include the title of the article (descriptive but as concise as possible); the complete names, titles, addresses, and professional affiliations of the authors; and phone, fax, and email address for the corresponding author, who will be assumed to be the first author unless otherwise noted. If the paper was presented before an organized group, the name of the organization, location, and date should be included. A 150- to 200-word abstract of the article must be included. Trade names: When a trade name of a product is used, the name of the manufacturer must appear parenthetically at first mention. Tables: Each table should be logically organized, typed on a separate page at the end of the manuscript, and numbered consecutively. Table title and footnotes should be typed on the same page as the table. Legends: There should be an individual legend for each illustration. Figure legends should be typed as a group on a separate page at the end of the manuscript. Detailed captions are encouraged. For microphotographs, specify original magnification and stain. References: References should be included on a separate page in the manuscript. Cite all references

numerically, in order of appearance in the text. Limit references to those specifically referred to in the text. Use the following style for the reference list: Journals: 1. A  l-Johany, SS, Alqahtani AS, Alqahtani FY, Alzahrani AH. Evaluation of different esthetic smile criteria. Int J Prosthodont 2011;24:64–70. Books: 1. G  ürel G. Porcelain laminate veneers: Predictable tooth preparation for complex cases. In: Romano R (ed). The Art of Treatment Planning: Dental and Medical Approaches to the Face and Smile. Chicago: Quintessence, 2010:249–263. Review Process Manuscripts will be reviewed by the editor and editorial staff with expertise in the field that encompasses the article. Original articles are considered for publication on the condition that they have not been published or submitted for publication elsewhere. The publisher reserves the right to edit all manuscripts to fit the space available and to ensure conciseness, clarity, and stylistic consistency. Article Acceptance Article acceptance is pending receipt of images judged to be of sufficient quality for publication (see the guidelines below). Once a manuscript is accepted, authors should submit high-quality nondigital images or high-resolution digital image files (on disk) to: Managing Editor American Journal of Esthetic Dentistry Quintessence Publishing Co, Inc 4350 Chandler Drive Hanover Park, IL 60133 The disk/package should be labeled with the first author’s name, shortened article title, and code number assigned upon acceptance. Nondigital Image Format. When submitting nondigital images please consider the following points: • Clinical photographs/radiographs. Submit original 35-mm slides, high-quality glossy prints, or original film. If arrows, letters, or numbers need to be added to the images, submit black-and-white or colored prints of each transparency with the appropriate labels drawn.

• Line drawings. Figures, charts, and graphs should be professionally drawn. Text should be large enough to be read after reduction. Good quality computergenerated laser prints are acceptable (no photocopies). Lines within graphs should be of a single weight unless special emphasis is needed. • The figure number, first author’s last name, and proper orientation should be indicated on each image. • Handle illustration materials carefully. Do not bend, fold, or use paper clips. Do not mount slides in glass. • For protection against damage or loss, authors should retain duplicate slides and illustrations. • All illustrations are returned after publication. Digital Image Format. When preparing final images to send, consider the following points: • Resolution must be at least 300 dpi when the image is 3 inches wide. • Images saved in TIFF format are preferred, but JPG or EPS files are acceptable. • Images grouped together must be saved as individual files. • Images containing type should either be saved as a layered file or provided along with a second file with type removed. • Line art (graphs, charts, line drawings) should be provided as vector art (Illustrator or EPS files) • Please do not embed images into other types of documents (eg, Word, Excel, PowerPoint, etc). Mandatory Submission Form The Mandatory Submission Form (accessible from AJED’s home page at www.quintpub.com) must be signed by all authors and faxed to the AJED Managing Editor (630-736-3634). Permissions and Waivers Permission of author and publisher must be obtained for the direct use of material (text, photos, drawings) under copyright that does not belong to the author. Waivers must be obtained for photographs showing persons. When such waivers are not supplied, faces will be cropped to prevent identification. Permissions and waivers should be faxed along with the Mandatory Submission Form to the AJED Managing Editor (630-736-3634).

Mandatory Submission Form and Copyright Assignment Agreement The American Journal of Esthetic Dentistry

Fax completed form to Publisher’s Office: 630-736-3634

This Agreement is made by each author signing below, in favor of Quintessence Publishing Co, Inc, an Illinois corporation (the "Publisher"), and pertains to:

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Minimally Invasive Restorative Treatment of Hypoplastic Enamel in Anterior Teeth Jussara Karina Bernardon, DDS, MS, PhD Clinical Professor, Department of Operative Dentistry, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.

Renata Gondo, DDS, MS, PhD Clinical Professor, Department of Operative Dentistry, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.

Luiz Narciso Baratieri, DDS, MS, PhD Professor, Department of Operative Dentistry, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.

Hypoplastic enamel can compromise the smile by altering the morphology and natural translucency of the teeth. To avoid performing iatrogenic procedures, etiologic knowledge of the enamel deficiency is essential to indicate the most appropriate treatment approach. In the case of white stains involving the enamel and dentin, a notable treatment option is a direct restoration with composite resin, which has excellent optical properties to reproduce the natural tooth structure and appropriate mechanical properties to ensure treatment longevity. In this article, a clinical case of a patient who reported dissatisfaction with her smile esthetics, prompted by the presence of hypoplastic enamel staining at the central and lateral incisors, is presented. Treatment consisted of composite resin restorations with the natural stratification technique. The final esthetic result proved the possibility of obtaining natural-looking restorations, while ensuring the esthetic and functional satisfaction of both the patient and clinician. (Am J Esthet Dent 2011;1:10–24.)

Correspondence to: Dr Jussara Bernardon Armaro Antônio Viera 2489, apto 403, Itacorubi, Florianópolis, Santa Catarina, Brazil. Fax: 55 048 38799226. Email: [email protected]

10 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Fig 1   Proximal view of the anterior teeth. Note the change in color and presence of white spots.

11 VOLUME 1 • NUMBER 1 • FALL 2011

Bernardon et al

S

everal factors may compro­

to the natural shine and trans-

mise the esthetics of the

lucency of enamel. This opacity

hypoplastic

prevents light transmission in

enamel, which may affect the

the specific region of the lesion,

morphology, texture, and color of

providing a distinct difference

the tooth surface, the result of an

between it and the surrounding

incomplete or defective forma-

enamel. Several types of treat-

tion of the enamel organic ma-

ments may be recommended

trix. The intensity and duration

according to severity, and the

of stimulation on ameloblasts

least invasive technique should

reflect the extent and location of

always take precedence. There-

enamel defects.1 Lesions may

fore, the etiologic diagnosis is of

be triggered by hereditary or

paramount importance and aims

environmental factors. With he-

to prevent unnecessary treat-

reditary factors, generally only

ment of the hypoplastic teeth.

the enamel of primary and per-

For mild (smooth, light) and su-

smile,

including

Hy-

perficial lesions, tooth bleaching

poplastic enamel resulting from

can be performed, with or with-

environmental factors, however,

out abrasion of the enamel. This

can be caused by a variety of

is a minimally invasive technique

influences, including nutritional

and is limited to the enamel of

deficiencies, rashes (eg, mea-

the affected area.6 In the case

sles,

chickenpox,

of moderate or severe stains

ver),

syphilis,

manent teeth is

affected.2

scarlet

fe-

hypocalcemia,

with

dentin

involvement,

the

systemic disorders, ingestion of

preferred treatment is a direct or

chemicals (eg, fluoride), trauma,

indirect restorative procedure.

infections of the primary denti-

With the ongoing development

tion, or by idiopathic causes.2,3

of composite resins, which pre-

Environmental factors usually af-

sent a wide range of available

fect only one arch and can alter

colors and excellent mechani-

dentin.4

cal properties, it has been pos-

both the enamel and

the

sible to perform more esthetic,

etiology, stains resulting from

predictable, and conservative

hypoplastic enamel may have

restorations.7 The use of com-

systemic features, affecting a

posite resin has the advantage

group of teeth, or be localized,

of minimal reduction of the tooth

with asymmetric distribution and

structure and the completion of

isolated to specific teeth.5

the procedure in a single ap-

Therefore,

These

depending

spots

on

compromise

smile esthetics because they have an opaque, rough, and irregular appearance, compared

12 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

pointment.8

Bernardon ET AL

Fig 2   Initial appearance of the patient. At conversation distance, the spots, while clearly visible, can be left untreated if they do not bother the patient. However, in this case, the patient was concerned about the appearance of her teeth.

Clinical case

enamel areas at the incisal and middle thirds of the maxillary and mandibular

The chief complaint of the patient was

incisors, without functional involvement

esthetic dissatisfaction from discolora-

(Figs 3 and 4). The patient underwent

tion of the teeth and the presence of

radiographic examination, and no peri-

white spots on the incisors (Figs 1 and

odontal or periapical changes were

2). After taking the case history with a

evident. The affected teeth yielded a

clinical examination, it was determined

positive response to the vitality test.

that the teeth were naturally dark and that the white spots were hypoplastic

An additional recommended baseline

examination

is

transillumination,

13 VOLUME 1 • NUMBER 1 • FALL 2011

Bernardon et al

Fig 3   Preoperative labial view demonstrating yellow coloration of the teeth and the presence of white spots at the incisal and middle thirds of the maxillary central incisors and incisal third of the left lateral incisor.

Fig 4   Occlusal view of the maxillary incisors. Note the change in morphology and surface texture.

which involves the use of a transillumi-

termining the treatment approach: the

nator positioned along the palatal sur-

less the light propagation through the

face of the tooth being assessed (Figs

affected areas, the greater the depth

5a to 5c). This technique allows analy-

of the stain. If the dentin is involved, the

sis of the transmission of light through

most common treatment approach is a

the hypoplastic defects, identification of

direct restoration with composite resin

the thickness of the affected areas, and

and limited preparation of the compro-

verification of the degree of compro-

mised surface.

mised enamel (and dentin, if affected).

Initially, because of tooth discolora-

Thus, transillumination is effective in de-

tion, the patient was asked to perform

14 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Bernardon ET AL

a

b

c

Figs 5a to 5c   Using a transilluminator placed on the palatal surface of the involved incisors, it was possible to visualize the stain depth and relate this to the depth of the hypocalcified area.

Fig 6   Frontal view after home bleaching with 10% carbamide peroxide gel for 4 weeks (2 hours/ day). Note that the stains remained visible, confirming the need for restorative intervention.

a supervised home whitening or bleach-

condition in terms of saturation and

ing

carbamide

brightness of the teeth to be restored.12

peroxide gel for 4 weeks (2 hours/day)

The restoration was performed 14 days

(Fig 6). Home bleaching is a relatively

after completion of the bleaching pro-

simple,

effective

cess to ensure that the adhesive proce-

treatment,9,10 with satisfactory results

dure and color selection were carried

regimen

obtained

with

10%

conservative, in

a

short

and time

period.11

out properly.13

Bleaching, associated with restorative

A microhybrid composite resin sys-

treatment, is a common approach that

tem (Opallis, FGM) with the appropri-

aims to establish a more homogenous

ate mechanical properties to ensure

15 VOLUME 1 • NUMBER 1 • FALL 2011

Bernardon et al

Fig 7 (left)  Choice of color using the color scale positioned on the facial surface of the affected tooth. The enamel and dentin colors were selected separately. Fig 8 (right)  By placing the dentin shade guide against the enamel shade guide, the final shade can be visualized.

strength and maintenance of polishing

chemistry of the different brands avail-

and surface brightness and sufficient

able. This is because the enamel and

optical properties to mimic the features

dentin shade guides vary in saturation

found in natural teeth was selected for

and translucency depending on the

procedure.14

A resin

system used. The color scale should

system with both enamel and dentin

be positioned as closely as possible to

shades is recommended because the

the tooth. The color selection for den-

natural tooth overlaps these structures

tin should be performed at the cervical

in different thicknesses, which creates

third of the affected tooth, where the

the polychromatic effect seen on natu-

dentin is thicker and more saturated,

the restorative

The selected system pre-

and enamel color selection should

sented several hues and saturations

occur at the middle third. The system

for enamel and dentin beyond the

used had separate scales for enamel

transparent resins, which reproduce

and dentin, which is an advantage be-

different degrees of translucency, opal-

cause it allowed for an individual evalu-

escence, and fluorescence.

ation of the structures. In addition, each

ral

teeth.15

When selecting the color for the res-

tab had a different thickness, and it was

toration, the teeth should be clean and

possible to predict the shade of the final

moist so that the natural translucency

restoration by altering the thickness of

is preserved.15 Color scales are essen-

the tab selected (Fig 7). By placing the

tial, and it is of paramount importance

enamel shade tab on top of the dentin

that they be of the same manufacturer

shade tab, it was possible to predict

as the resin system selected to avoid

how the resins would interact in the

potential discrepancies between the

future restoration (Fig 8). The operative

16 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Bernardon ET AL

Fig 9   After rubber dam was

Fig 10   Occlusal view of the

Fig 11   After preparation,

used to isolate the affected

preparation. Note the remaining

the white spot was still evident,

teeth, the white spot was re-

white spot that could compro-

which called for its removal

moved using diamond burs.

mise the restorative outcome if

with a diamond bur of smaller

not removed.

diameter.

Fig 12   Final aspect of the

Fig 13   Etching of the hard

Fig 14   Application of the ad-

hydrated cavity preparation,

tissue with 37% orthophosphoric

hesive system according to the

which was restricted to removal

acid (15 seconds for dentin,

manufacturer’s instructions.

of the white spot.

30 seconds for enamel).

field was isolated to ensure a clean and

There is no need to bevel the cavo-

suitable environment for the bonding

superficial angle, preserving as much

procedures.

healthy tooth structure as possible (Fig

The cavity preparation should be

12). The absence of preparations en-

restricted to removing the hypoplastic

sures a reversible treatment without

enamel using diamond points com-

compromising esthetics or the adhe-

patible to the size of the lesion under

sive bond. After the preparation was

constant irrigation to avoid heating of

complete, conditioning was performed

the structure (Fig 9). The entire depth

with 37% orthophosphoric acid for 15

of the hypoplastic enamel should be

seconds on the dentin and 30 seconds

removed. Otherwise, the resulting dif-

on enamel (Fig 13), followed by appli-

ference in opacity between natural and

cation of the adhesive system, accord-

affected tooth structure can negatively

ing to the manufacturer’s instructions

affect the outcome of the restoration

(Fig 14).

(Figs 10 and 11).

17 VOLUME 1 • NUMBER 1 • FALL 2011

Bernardon et al

Fig 15   Composite resin was

Fig 16   Mamelons must be

Fig 17   Frontal aspect after

placed in the preparation to

defined when applying the

placing the second dentin resin

reproduce the dentin layer.

composite resin.

layer for bleached teeth. Note the design of the mamelons.

The restorative procedure was per-

an “orange” appearance. This is the

formed using the stratification tech-

counter-opalescence feature of dentin.

nique, based on the techniques of

To reproduce this effect, an opalescent

building ceramics. This new trend is

and highly translucent resin (T-Blue,

also referred to as the anatomical tech-

Opallis) was placed on the tips of the

nique.16,17 In this technique, layers of

mamelons and between the dentin and

selected materials are used to repro-

incisal edge of the tooth (Fig 18).

duce the enamel and dentin structures

Then, artificial enamel was recon-

while also respecting their thickness

structed using a single enamel resin

and anatomical contour.

layer (E-Bleach) (Fig 19). In the stratifi-

The artificial dentin reconstruction

cation technique, it is important to con-

was performed using the dentin resin

sider that the artificial enamel thickness

DA1 (Opallis). This resin was applied

should correspond to one third of that of

covering the deepest portion of the cav-

natural enamel18 to avoid value reduc-

ity to sculpt the shape of the mamelons

tion of the restoration. This means that

(Figs 15 and 16). Dentin mamelons can

a thicker layer of artificial enamel results

have various shapes and determine

in a gray and more monochromatic res-

the

characteristics

toration.14 This is because the refrac-

of the tooth (Fig 17). Each layer was

tory index of the natural tooth structure

photopolymerized for 40 seconds. To

is different from that of the composite

complete the artificial dentin, a resin for

resin.14 The enamel surface was final-

bleached teeth was applied at the tip

ized at this time, avoiding use of dia-

of the mamelons (D-Bleach, Opallis).

mond points (Fig 20).

translucent

halo

In a natural tooth, dentin presents as

The same procedures were per-

an intense and very reflective opaque

formed for the maxillary right central

white color on the tip of the mamelons.

(Figs 21 to 24) and left lateral inci-

However, when light penetrates the

sors (Figs 25 to 28). After complete

dentin through the enamel, it results in

polymerization and at a later session,

18 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Bernardon ET AL

Fig 18    A highly translucent

Fig 19   Positioning of the final

Fig 20   Proximal view of the

resin was placed on the opal-

enamel composite resin layer.

vertical development and lobes

escent areas of the incisal third

Care was taken to cover all

shaped in the definitive restora-

region of the tooth.

preparation margins.

tion.

Fig 21   Removal of the white

Fig 22   After hydration, the

Fig 23   Incremental tech-

spots on the right central inci-

preparation was completed

nique for resin application:

sor with a diamond bur.

with removal of the white spot.

DA1, D-bleach H, T-Blue, and Bleach (Opallis).

Fig 24   Final aspect of the

Fig 25   Removal of the hypo-

Fig 26    Final aspect of the hy-

restoration of the maxillary right

plastic enamel on the left lateral

drated cavity preparation, which

central incisor.

incisor.

was restricted to removing only the hypoplastic white spot.

Fig 27 (left)  Mamelon design using dentin resin (DA1 and DBleach, Opallis). Fig 28 (right)  Final aspect of restoration. Note the contrast between the restoration and the natural tooth, which is dehydrated as a result of absolute isolation.

19 VOLUME 1 • NUMBER 1 • FALL 2011

Bernardon et al

Fig 29   A surface enhancer was used to identify the differ-

Fig 30   Vertical development and

ent reflection areas of the teeth.

the edges were completed with an oval format extra-fine diamond bur.

Fig 31   Note the similarity in morphology between the cen-

Fig 32   The restoration was pol-

tral incisors after texturing.

ished to make the surface bright and smooth.

the surface of the restoration was tex-

an irregular surface provides light dis-

tured, and finishing and polishing were

persion. Lobules and development

completed (Figs 29 to 32). Surface tex-

grooves (vertical texture), horizontal

turing is indispensable in ensuring a

grooves, and perikymata should be

natural-looking

reproduced using extra-fine diamond

restoration

because

20 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Bernardon ET AL

a

b

c

Figs 33a to 33c   A transilluminator was again used to visualize the similarity in light transmission between tooth and restoration (compare to Figs 5a to 5c).

Fig 34   Final aspect of restorations, frontal view. Fig 35 (right)  Final aspect of restorations, palatal view.

burs. Finishing was completed using

result showed that composite resin

flexible disks and rubber tips. Polish-

provides a suitable material to produce

ing with felt disks and polishing pastes

esthetic effects similar to that of the

ensures surface brightness and de-

natural tooth structure (Figs 33 to 39).

creases plaque retention. The final

21 VOLUME 1 • NUMBER 1 • FALL 2011

Bernardon et al

Figs 36 to 38   Final smile after bleaching and restorative treatment. Note the correct merging of the dental substrate with the composite resin and reproduction of the optical aspects in the incisal third region.

22 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Bernardon ET AL

Fig 39   The patient was satisfied with the end result. Note the naturalness and harmony of the smile with the facial esthetics.

23 VOLUME 1 • NUMBER 1 • FALL 2011

Bernardon et al

Conclusions and guidelines for practitioners

properties, and reproduction of the natural tooth color and characteristics.19 Proper color selection is not enough; satisfactory resin system selection and

In cases of hypoplastic enamel, a correct

proper realization of the stratification

diagnosis is indispensable for an appro-

technique must also be accomplished.

priate treatment prognosis. In lesions

Following this protocol is critical to the

with dentin involvement, direct compos-

quality of treatment received.

ite resin restorations promote satisfactory results with conservation of a healthy dental structure, excellent mechanical

This article is based on a chapter in the book Clinical Vision: Cases and Solutions by Dr Baratieri and was originally written in Portuguese.

References   1. Elcock C, Smith RN, Simpson J, Abdellatif A, Bäckman B, Brook AH. Comparison of methods for measurement of hypoplastic lesions. Eur J Oral Sci 2006;114(suppl 1): 365–369.   2. Clarkson J. Review of terminology, classifications, and indices of developmental defects of enamel. Adv Dent Res 1989;3:104–109.   3. Ribas AO, Czlusniak GD. Anomalias do esmalte dental: Etiologia, diagnostico e tratamento. Biol Health Sci 2004;10:23–26.   4. Bendo CB, Scarpelli AC, Novaes JB Jr, Valle MPP, Paiva SM, Pordeus IA. Enamel hypoplasia in permanent incisors: A six-month follow-up. RGO 2007;55:107–112.   5. Sensi lG, Marson FC, Strassle H, Duarte SJ. Recuperação Cosmética de Deformidades Dentais. Pro-odont Estética, ed 2. Porto Alegre: Artmed, 2008: 156–178.   6. Croll TP. Enamel Microabrasion. Chicago: Quintessence, 1991.   7. Simonsen RJ. Developmental defect restorations. In: Simonsen RJ. Clinical Applications of the Acid Etch Technique. Chicago: Quintessence, 1978:63–70.

  8. Machado FC, Ribeiro RA. Defeito de esmalte e cárie dentária em crianças prematuras e/ou de baixo peso ao nascimento. Pesq Bras Odontoped Clin Integr 2004; 4:243–247.   9. Haywood VB, Heymann HO. Nightguard vital bleaching. Quintessence Int 1989;20: 173–176. 10. Leonard RH Jr, Bentley C, Eagle JC, Garland GE, Knight MC, Phillips C. Nightguard vital bleaching: A long-term study on efficacy, shade retention, side effects and patients’ perceptions. J Esthet Restor Dent 2001;13:357–369. 11. Joiner A. The bleaching of teeth: A review of the literature. J Dent 2006;34:412–419. 12. Hirata R. Tips: Dicas em Odontologia Estética. São Paulo: Artes Médicas, 2011:576. 13. McGuckin RS, Thurmond BA, Osovitz S. Enamel shear bond strengths after vital bleaching. Am J Dent 1992;5:216–222 14. Baratieri LN, Belli R. Resinas compositas. In: Baratieri LN. Clinical Solutions—Fundamentals and Techniques. Florianópolis: Editora Ponto, 2008:131–142.

24 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

15. Baratieri LN, Belli R. Colo: Fundamentos básicos. In: Baratieri LN. Clinical Solutions—Fundamentals and Techniques. Florianópolis: Editora Ponto, 2008:21–55. 16. Ardu S, Krejci I. Biomimetic direct composite stratification technique for the restoration of anterior teeth. Quintessence Int 2006;37:167–174 [erratum 2006;37:408]. 17. Vanini L. Light and color in anterior composite restorations. Pract Periodontics Aesthet Dent 1996;8:673–682. 18. Vanini L, Mangani F, Klimovskaia O. Colour in dentistry. In: Vanini L, Mangani F, Klimovskaia O. Conservative Restoration for Anterior Teeth. Viterbo, Italy: ACME, 2005:97–200. 19. Bernardon JK, Gondo R. Restorative treatment of hypoplastic stains in anterior teeth. In: Baratieri LN. Clinical Vision: Cases and Solutions. Florianópolis: Editora Ponto, 2010:62–101.

The Gray Zone Around Dental Implants: Keys to Esthetic Success Iñaki Gamborena, DMD, MSD, FID Private Practice, San Sebastian, Spain; Clinical Assistant Professor, Department of Preventive and Restorative Sciences, University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvania, USA.

Markus B. Blatz, DMD, PhD Professor and Chairman, Department of Preventive and Restorative Sciences, University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvania, USA.

Correspondence to: Dr Iñaki Gamborena Resurecccion mª de Azkue, 6 20018 San Sebastian, Spain. Email: [email protected]

26 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Single-implant restorations in the anterior maxilla have become a routine treatment option. While customized tooth-colored prosthetic components show greatly improved clinical outcomes, esthetic success relies not only on the restorative result, but also on the condition of the soft tissues. A common esthetic shortcoming is the grayish appearance of the peri-implant soft tissues, which are difficult to manipulate around dental implants. The parameters and clinical guidelines that should be used to influence esthetic success and avoid the gray zone around implant restorations can be categorized into five key factors: (1) optimal threedimensional implant placement for functional and esthetic long-term implant success; (2) maximized soft tissue thickness to conceal the implant-restorative interface; (3) proper abutment selection to improve biocompatibility, tissue stability, color, translucency, and fluorescence; (4) careful crown restoration to imitate the natural teeth; and (5) awareness of the lip line, which may greatly influence the final outcome. Mimicking the inherent optical properties, especially fluorescence, of natural teeth with implant components and crown materials is fundamental for ideal restorative and soft tissue esthetics. (Am J Esthet Dent 2011;1:26–46.)

27 VOLUME 1 • NUMBER 1 • FALL 2011

Gamborena and Blatz

T

he esthetic success of a dental

and restorative esthetic success with

restoration is judged by its inte-

maxillary anterior implant-supported

gration with the surrounding dentition

restorations presents a great challenge

in respect to position, angulation, di-

for the entire dental team and depends

mensions, proportions, shape, surface

on a variety of parameters.10–14

morphology, and shade.1–3 Other cru-

The parameters and clinical guide-

cial esthetic parameters that are often

lines that should be used to influence

overlooked include the morphology,

esthetic success and avoid the gray

texture, and ultimately the color of the

zone around implant restorations can

surrounding gingiva.3,4 The soft tissue

be categorized into five key factors: (1)

is the natural frame of the teeth and

optimal three-dimensional (3D) implant

any dental restoration and is, therefore,

placement for functional and esthetic

a fundamental parameter for esthetic

long-term implant success; (2) maxi-

success.1,3,5 This aspect is often ne-

mized soft tissue thickness to conceal

glected because successful soft tissue

the implant-prosthetic component inter-

outcomes—including handling, manip-

face; (3) proper abutment selection to

ulation, and healing—are very demand-

improve biocompatibility, tissue stabil-

ing, time intensive, and unpredictable.5

ity, and color to provide a perfect blend

described a prevalence

with surrounding tissues and teeth; (4)

of grayish soft tissue discolorations

careful crown restoration to imitate the

around tooth-supported full-coverage

natural teeth; and (5) awareness of the

porcelain-fused-to-metal and even all-

lip line, which may greatly influence the

ceramic restorations. Interestingly, oth-

final outcome.

Magne et

al6

er perioral facial parameters such as position of the upper lip and height of the smile line7–9 also seem to influence

3D implant placement

the degree of gingiva discoloration. The authors note that “this problem is

The fundamental factor for long-term

particularly evident in the presence of

functional and esthetic success as well

the upper lip, which can generate an

as soft tissue color and stability is opti-

‘umbrella effect’ characterized by gray

mal 3D implant placement.18 A simple

marginal gingivae and dark interdental

but essential guideline is to position the

papillae.”6

implant as close as possible to where

This umbrella effect is magnified with

the natural tooth was or ideally would

dental implant restorations in the an-

be.10 If a line is drawn at the center of

terior maxilla because the supporting

the implant along its long axis and ex-

hard and soft tissues are often com-

tending through the tooth restoration,

promised even before restorative treat-

it should run through the center of the

ment and are influenced by the color

incisal edge of the prospective tooth

and design of the implant, its prosthetic

(Fig 1). The greater the 3D mismatch

components, and the definitive resto-

between the crown and implant body,

ration.10–17 Therefore, ideal periodontal

the poorer and less stable the final

28 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Gamborena and Blatz

Fig 1 (right)  Maxillary anterior implants should be positioned and angulated so that a virtual line through the center of the implant along its long axis would run through the center of the incisal edge of the prospective crown.

outcome will be. The incisal edge is also the target for the angulation of the implant. An implant that is angulated too far to the buccal aspect will result in greater tissue recession under functional load. Conversely, a palatally placed implant leads to a more extreme emergence profile, resulting in increased bone resorption and thinning of the tissues. Both situations will lead to an intensified grayish appearance of the soft tissues at the gingival margin. The third dimension is determined by the depth of the implant in respect to the marginal bone and soft tissue. An implant placed at the proper depth allows for the development of an ideal emergence profile and a soft tissue collar void of a gray zone. It is impossible to create a proper emergence profile when the implant is placed too shallow, while an implant placed too deep is difficult to manage clinically and increases the possibility of peri-implant infection, inflammation, and bone loss. A surgical guide fabricated from the diagnostic wax-up/setup is an indispensible tool to ensure proper 3D implant placement. The anticipated incisal

Soft tissue thickness

edge position of the final tooth restoration determines the position, angulation,

Even in cases where ideal implant

and depth of the implant in all three di-

placement was achieved, the esthetic

mensions, which directly influence the

outcome may become compromised

position, height, and thickness of the

over time due to resorption of the mar-

surrounding hard and soft tissues.10,12

ginal bone and soft tissues.5,19

29 VOLUME 1 • NUMBER 1 • FALL 2011

Gamborena and Blatz

Case 1

Figs 2a and 2b   A modified metal abutment was used after im-

Fig 3   Postoperative situation

mediate implant placement at the maxillary right central incisor site

showing the implant-supported

without bone or soft tissue augmentation.

crown.

Fig 4 (above left)  Follow-up view after several years reveals a grayish appearance of the soft tissues. Fig 5 (above right)  Follow-up view after 11 years showing soft tissue discoloration due to the metal abutment. Fig 6 (left)  Periapical radiograph after 11 years reveals loss of buccal bone.

Case 1 (Figs 2 to 6) illustrates a situa-

inserted (Figs 2 and 3). A follow-up

tion where a single implant was placed

photograph taken several years post-

immediately after extraction of the

operatively reveals a grayish appear-

maxillary right central incisor without

ance of the soft tissue surrounding the

any hard or soft tissue augmentation. A

implant restoration (Fig 4). This discol-

modified metal abutment was fabricat-

oration becomes increasingly evident

ed, and the definitive restoration was

11 years after completion as a result of

30 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Gamborena and Blatz

the resorption of the buccal bone and

connective tissue grafting, is another

surrounding soft tissues, revealing the

critical issue. Connective tissue grafts

unfavorable gray color of the metal im-

(CTGs) are placed around implants to

plant abutment (Figs 5 and 6).

enhance gingival margin stability and

To avoid this result, it is advisable

create a more fibrous and less mobile

to maximize tissue thickness in every

tissue complex.19–22 In dentistry today,

case and for both delayed and imme-

the clinician’s search for soft tissue

diate implant placement.19–22 In fact,

abundance in the early stages of im-

the mucosal characteristics of the peri-

plant treatment means creating a large

implant tissues necessitate connective

amount of soft tissue during or soon af-

tissue grafting for long-term esthetic

ter implant placement and manipulat-

success.21 With clear surgical objec-

ing these tissues during the prosthetic

tives, a modern approach should al-

phase. This is a shift from traditional ap-

ways include the most conservative

proaches in which multiple subsequent

procedure that satisfies the esthetic

soft tissue grafts are performed until

and functional requirements. For ex-

the desired thickness was achieved.

ample, if a bone graft is unnecessary,

Multiple surgical interventions, how-

stage-one surgery should always be

ever, are less predictable because

performed with a minimal flap incision,

the scarring and compromised blood

such as a split-thickness flap or even

supply make every subsequent graft-

no flap, to avoid unnecessary exposure

ing

of the underlying bone. Several authors

ideal prosthetic soft tissue manipula-

have indicated that flapless surgical

tion, the healing abutment should be

implant placement using computer-

significantly narrower than the tooth to

assisted

attempt

more

challenging.

For

minimizes

be replaced. At first, the tissue will not

bone resorption, preserves soft tissue

have the same scalloped architecture

architecture, and improves the healing

as found around natural teeth. How-

process.23 While some of these results

ever, when the provisional restoration

still need to be verified in long-term clin-

is placed, its subgingival contour and

ical trials, the positive effects of flapless

shape will determine the position and

implant placement on patient comfort

scallop of the soft tissue margin.10,13 It

due to the minimally invasive nature

also seems advantageous to connect

evident.23

the definitive abutment as early as pos-

The key components of this surgical

sible and not to remove it after that time.

surgical

guides

of the procedure are clearly

process are maintenance of the inter-

Thicker

peri-implant

soft

tissue

proximal bone, minimal bone exposure

masks the implant-abutment-restoration

only on the implant site, precise coro-

interface and provides a better color

nal graft suturing central to the implant

match between the soft tissues around

axis, and tension-free flap closure and

the implant and those around the neigh-

adaptation.

boring teeth.15–17 Some basic guide-

The design of the healing abutment, which can be placed during or after

lines for tissue thickness and abutment selection are as follows:

31 VOLUME 1 • NUMBER 1 • FALL 2011

Gamborena and Blatz

Case 2

Fig 7   Thin peri-implant soft

Fig 8   A custom-colored

Fig 9   Colored zirconia abut-

tissue of only 1 mm was

zirconia abutment (Procera, No-

ment and alumina crown

evident on the buccal aspect.

bel Biocare) was fabricated to

(Procera Crown Alumina, Nobel

optimize the esthetic outcome.

Biocare).

Fig 10   Intraoral occlusal view

Fig 11   Postoperative buc-

showing the soft tissue support.

cal view. The tooth-colored abutment and all-ceramic crown blend favorably with the adjacent teeth and surrounding soft tissue despite the compromised soft tissue thickness.

Fig 13 (left)  Occlusal view of

Fig 12   Postoperative peri­

the definitive implant-supported

apical radiograph.

restoration.

• A soft tissue thickness greater than

along with the adequate soft tissue sup-

3 mm allows for the use of titanium or

port and contour, provided a satisfying

zirconia abutments without negative

outcome.

esthetic implications. • A thin soft tissue of less than 2 to 3 mm requires either a CTG or zirco-

Abutment selection

nia abutment. • A dentin-colored abutment is always preferred.

In an evaluation of the soft tissue around single-tooth implant crowns, Fürhauser et al24 showed that the color of the peri-

In Case 2 (Figs 7 to 13), a colored in-

implant soft tissue matched that of the

stead of a white zirconia abutment was

reference tooth in no more than one-

placed due to the presence of less than

third of cases. Another study found that

1 mm of labial soft tissue. This approach,

all-ceramic implant abutment and crown

32 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Gamborena and Blatz

Case 3

Fig 15   Preoperative intraoral situation.

Fig 16   Lateral tomogram showing the extent of the ridge defect.

Fig 14   Preoperative periapical radiograph of the missing maxillary left central incisor.

Fig 17   Intraoral view of the edentu-

Fig 18   Virtual

lous ridge topography.

implant placement for guided surgery.

materials provide a better soft tissue

dental implant (Figs 14 to 18). Ideal 3D

color match with neighboring teeth than

implant placement was planned on the

do conventional metal-alloy compo-

computer and transferred via guided

nents.16 Zirconia has been shown to be

surgery.

the preferred implant abutment material

the implant (3.5 × 13 mm, NobelAc-

due to its high strength13,25,26 and ex-

tive, Nobel Biocare) was inserted, and

biocompatibility.27–29

During

stage-one

surgery,

The short-

a CTG harvested from the maxillary

comings of zirconia include its higher

tuberosity was placed to increase tis-

cost and unfavorable optical properties

sue thickness (Figs 19 to 23). Figure

in regard to color and fluorescence.30

24 shows the augmented edentulous

cellent

Case 3 (Figs 14 to 55) includes all

ridge 6 months postoperatively. Next,

previously described factors and treat-

a zirconia abutment was connected to

ment parameters. The missing maxillary

the implant, and a provisional restora-

left central incisor was replaced with a

tion was fabricated, relined in the oral

33 VOLUME 1 • NUMBER 1 • FALL 2011

Gamborena and Blatz

Case 3   Continued

Fig 19   Implant placement (3.5 × 13 mm,

Fig 20   A subepithelial CTG was harvested

NobelActive, Nobel Biocare).

from the maxillary tuberosity to augment the deficient ridge.

Fig 21   After placement of the CTG, the flaps

Fig 22   Labial view of the adapted flap after

were adapted without tension and sutured with thin

suturing.

suture material to limit trauma.

Fig 23   Intraoral situation 1 week postopera-

Fig 24   Postoperative situation after 6 months

tively.

reveals improved ridge morphology.

cavity, and cemented (Figs 25 to 29).

Figs 30 to 33 reveal the optical short-

The different lighting conditions (natu-

comings of these materials, especially

ral and ultraviolet [UV] light) shown in

the lack of natural fluorescence. Figure

34 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Gamborena and Blatz

Case 3   Continued

Fig 25   Definitive zirconia abutment and provisional restoration. Fig 26 (right)  Insertion of the colored zirconia abutment.

Fig 27 (above left)  Try-in of the provisional crown. Fig 28 (above right)  Precision of fit was verified extraorally. Fig 29 (right)  Periapical radiograph used to verify fit.

34 shows the detailed optical charac-

applied to zirconia abutments even af-

teristics of natural enamel and dentin

ter milling and finishing have recently

under different light sources.

been developed.30 The abutment or

Fluorescence is a crucial property for natural

esthetics.30–32

framework is dipped into a fluores-

Colorants

cent coloring liquid before sintering

and fluorescent modifiers that can be

to infiltrate the zirconia (Colour Liquid

35 VOLUME 1 • NUMBER 1 • FALL 2011

Gamborena and Blatz

Case 3   Continued

Fig 30   Optical properties of the provisional

Fig 31   Optical properties of the provisional

crown under natural light.

crown under UV light. Note the lack of fluorescence.

Fig 32   Optical properties of the zirconia abut-

Fig 33   Optical properties of the zirconia abut-

ment under natural light.

ment under UV light reveals a lack of fluorescence. Fig 34   Color characteristics of natural enamel and dentin: (a) The three basic color zones; (b) areas of brightness/value; (c) enamel characteristics under a polarizing filter; (d) color characteristics of dentin; (e) degrees of dentin fluorescence under UV light.

Fluoreszenz, Zirkonzahn). The abutment is blow dried after the dipping

In addition to the regular zirconia, a more

translucent

zirconia

process to remove the excess and then

Zirconia

placed under a drying lamp to prevent

along with 16 coloring liquids (Zirkon-

damage to the heating elements of the

zahn) are available. Figures 35 to 37

sinter furnace.

illustrate the infiltration process and its

36 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

“Translucent,”

(Prettau

Zirkonzahn)

Gamborena and Blatz

Case 3   Continued Fig 35   Three different abutments were fabricated with conventional zirconia, a more translucent zirconia (Prettau Zirconia “Translucent”), and fluorescent colorants (Colour Liquid Fluoreszenz): colored translucent zirconia with fluorescence (transl + fluoresc) and without fluorescence (translucent), and conventional zirconia with fluorescence (Zr + fluoresc). Natural light reveals the chroma characteristics.

Fig 36   Fabrication of a fluorescent abutment: (a) Provisional composite abutment; (b) duplicated zirconia abutment before the sinter process; (c) dipping of the zirconia abutment into fluorescent colorants before sintering; (d) definitive abutment after sintering.

Fig 37   The three different abutments under UV light. Conventional colored zirconia and fluorescing liquid (Zr + fluoresc) reveal the most favorable effect.

effect on the optical appearance under

tient’s favorable soft tissue thickness

different light sources. Three different

and the clinical try-in of the three differ-

abutments were fabricated: translucent

ent abutments under regular and UV

zirconia with and without fluorescence

light. Interestingly, the translucent abut-

and conventional zirconia with fluores-

ment provided the best match in natu-

cence. Figures 38 to 40 show the pa-

ral light but the worst under UV light.

37 VOLUME 1 • NUMBER 1 • FALL 2011

Gamborena and Blatz

Case 3   Continued

Fig 38 (above left)  Intraoral try-in of the three abutments under natural light. Fig 39 (above right)  Ideal soft tissue thickness (> 3 mm). Fig 40 (left)  Intraoral try-in of the three abutments under UV light.

The most favorable fluorescent effect was achieved with colored conventional zirconia and fluorescing liquid. In summary, the selection of zirconia

value,

translucency,

and

shade

(chroma and hue). • Color of the intended crown restoration (alumina versus zirconia).

implant abutments should be based on the following factors:

For optimal stability and fit of the coping, the preparation margin of the

• 3D implant position: The screw-

implant abutment is generally a circum-

access opening in the abutment

ferential chamfer or rounded shoulder.

should not compromise mechani-

On the labial aspect, the margin is typi-

cal strength, and the circumferential

cally placed deeper than on the palatal

thickness should be at least 0.8 mm.

aspect, but should not extend more than

• Soft tissue thickness: A minimum of 3 mm is ideal.

1 mm subgingivally to avoid difficulties during cement removal. The abutment

• Interocclusal space: Sufficient abut-

should support approximately 90% of

ment height is required for ideal

the total surrounding soft tissue con-

strength and resistance.

tour, with the crown supporting no more

• Implant abutment color: The order of priority should be fluorescence/

38 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

than 10%.30

Gamborena and Blatz

The provisional restoration generally

while enamel has low fluorescent prop-

remains in place for 4 to 6 weeks until

erties.30–32 Ceramic coping materials

the position of the tissue is stable. A

such as alumina37 and zirconia39 do

final impression of the abutment should

not provide natural fluorescence and,

then be made to transfer this informa-

therefore, are treated with fluorescent

tion to the laboratory for fabrication of

modifiers and/or veneered with fluores-

the definitive restoration.

cent dentin stains, liners, and shoulder porcelains.30,37,39 As in natural teeth, the fluorescent effect is most prominent

Crown restoration

in the gingival third of the restoration. Therefore, natural fluorescence does

The definitive crown material is se-

not only influence the optical effects of

lected based on its core structure to

the restoration itself, but also greatly in-

enhance the optical characteristics of

fluences the color and appearance of

the intended restoration. The coping

the surrounding soft tissues.30

is chosen by its ability either to mask

Figures 41 to 55 show the selection

underlying structures or to complement

of the definitive coping material and the

the underlying abutment color. Zirconia

final outcome of Case 3. Figures 41 and

is increasingly used as a coping ma-

42 reveal the influence of fluorescent

terial due to its versatility in respect to

stains on the value and chroma of alu-

strength, thickness, color, and translu-

mina and zirconia copings under natu-

cency, but especially due to its inherent

ral and UV light. The impact of using a

brightness and options for fluorescence

fluorescent (Fig 43) versus a nonfluo-

through infiltration.13–17,30 It seems only

rescent coping (Fig 44) is quite obvious

logical that when a fluorescent abut-

on the stone cast (Figs 45 and 46) and

ment is used, the material selected for

even more so in the oral cavity (Figs 47

the definitive crown should also offer a

to 55). The definitive implant-supported

certain degree of fluorescence to match

crown shows optical and fluorescent

It is

properties that ideally match the exist-

important to evaluate the optical prop-

ing natural dentition under various light

erties of the coping in relation to the

sources.

the adjacent natural

dentition.30–32

remaining natural dentition under different light sources. UV light reveals the dramatic effects of fluorescence, which

Lip line

provides the vitality and brightness exhibited by natural teeth.

A high lip line or “smile line” that reveals

Fluorescence is an inherent property

all anterior teeth and large amounts of

of natural teeth31,32 but is rarely found

gingival tissue7,8 is a great challenge

in “esthetic” dental

materials.33–40

In

for the dental team since it is impossible

natural teeth, the root and coronal den-

to hide the implant-restorative interface.

tin show the highest degree of fluores-

A high smile line may be due to vertical

cence, especially in the gingival third,

maxillary excess or a hypermobile lip.

39 VOLUME 1 • NUMBER 1 • FALL 2011

Gamborena and Blatz

Case 3   Continued

Fig 41   The influence of fluorescent stains on

Fig 42   Fluorescent properties of alumina and

the value and chroma of alumina and zirconia

zirconia copings under UV light: (a and c) without

copings under natural light: (a and c) without

fluorescence; (b and d) with fluorescence.

fluorescence; (b and d) with fluorescence.

Fig 43   Definitive fluorescent abutment on the

Fig 44   Nonfluorescent coping on the cast

stone cast demonstrating ideal fluorescence

under UV light.

under UV light.

Fig 45   Fluorescent coping on the cast under

Fig 46   Definitive crown showing fluorescent

UV light.

properties under UV light.

It is a common rule that, besides be-

canines, while the margins of the lateral

ing symmetric, the most cervical aspect

incisors should be approximately 1 mm

of the gingival margins of the central in-

below an imaginary line drawn from

cisors should be at the same level as the

the canine-centrals-canine.1 It seems

40 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Gamborena and Blatz

Case 3   Continued

Fig 47   Intraoral try-in of definitive crown under

Fig 48   Intraoral try-in under UV light demon-

natural light shows an excellent blend with the

strates ideal blending of the fluorescent properties

shade of the adjacent teeth.

of the definitive crown with the adjacent teeth.

Fig 50   Postoperative occlusal view showing the soft tissue support and contour.

Fig 49   Definitive implant restoration. Fig 51 (right)  The definitive abutment and restoration provide the same degree of fluorescence as a natural tooth.

advisable for central incisor implant

extremely helpful to counterbalance

restorations to initially place the gingi-

tissue recession typically seen over

val margin slightly more incisally. This

time. The CTG now becomes an essen-

slight “overcompensation” will prove

tial aspect for functional and esthetic

41 VOLUME 1 • NUMBER 1 • FALL 2011

Gamborena and Blatz

Case 3   Continued

Fig 52   Postoperative view under natural light

Fig 53   Postoperative view under UV light

showing the color match of the implant-supported

showing the ideal blend of fluorescent properties

crown with the natural dentition.

between the restoration and natural dentition.

Fig 54   Postoperative intraoral situation. No gray zone is evident.

Fig 55   One-year postoperative peri­apical radiograph of the implant at the left central incisor site.

integration of the implant-supported

natural and implant-supported teeth.

restoration, especially in the presence

The added connective tissue causes

of a high lip line.

the fibrotic mucosa around the implant

Occasionally, unfavorable changes

to migrate more coronally. In rare cas-

of the gingival margin levels may occur

es, the additional soft tissue becomes

at the teeth adjacent to the implant res-

so abundant that a gingivectomy fol-

toration. These are based on the dis-

lowed by a fibrotomy becomes neces-

tance between the free gingival margin

sary to establish ideal crown lengths

and the supporting bone and may re-

and gingival margin contours.

quire more extensive tissue grafting

The unfavorable umbrella effect is

to control gingival levels at both the

most prevalent in patients with a high

42 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Gamborena and Blatz

Case 4

Fig 56   Intraoral view of the definitive zirconia

Fig 57   A CTG was placed earlier to ensure

abutment.

ideal soft tissue thickness.

Fig 58   Intraoral situation after 1 year reveals

Fig 59   Preoperative view showing the patient’s

differences in peri-implant soft tissue color and

high lip line.

morphology.

Fig 60   Postoperative situation. An unfavorable

Fig 61   A high smile reveals the gray zone

gray zone is visible during an average smile.

through the umbrella effect.

smile line.6 The gray zone may become

the upper lip, causing a shadow on the

visible at the implant restoration site

soft tissue and the light to be reflected

even when all of the key factors are im-

and transferred in a different manner.

plemented perfectly. Differences in soft

Case 4 (Figs 56 to 61) demonstrates

tissue thickness and volume may cause

a situation in which the maxillary left cen-

these color dissimilarities, which are

tral incisor was replaced with an implant-

then amplified by the shear presence of

supported crown in a patient with a high

43 VOLUME 1 • NUMBER 1 • FALL 2011

Gamborena and Blatz

Case 5

Fig 62   Intraoral view of the crown prepara-

Fig 63   UV light reveals the natural fluores-

tion of the right central incisor and the definitive

cence of the modified zirconia implant abutment.

colored zirconia implant abutment at the left central incisor.

Fig 64   Preoperative intraoral view of the failing

Fig 65   Postoperative intraoral situation show-

central incisor crowns.

ing the color and soft tissue match.

Fig 66   Initial situation. Note the high lip line.

Fig 67   Successful implementation of the five key factors prevented the appearance of a gray zone despite the high smile line.

smile line. A CTG was placed to en-

In contrast to the previous case,

hance the soft tissue contours. While all

Case 5 (Figs 62 to 67) exemplifies

of the key aspects were implemented

successful implementation of these

successfully, the slight differences in

key factors in a patient with a high lip

soft tissue volume created an unfavora-

line for long-term esthetic and func-

ble grayish effect (Figs 60 and 61).

tional success.

44 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Gamborena and Blatz

Conclusions

Acknowledgments

Five key factors were identified to avoid

The authors would like to thank Iñigo Casares for the beautiful porcelain work featured in this article and Fernando Zozaya for the detailed fabrication on the zirconia abutments.

the gray zone around maxillary anterior implant restorations: 3D implant placement, soft tissue thickness, abutment selection, crown restoration, and lip line. Mimicking the inherent optical properties, especially fluorescence, of natural teeth with ideal prosthetic implant components and crown materials is fundamental for ultimate restorative and soft tissue esthetics.

References   1. Chiche G, Pinault A. Esthetics of Anterior Fixed Prosthodontics. Chicago: Quintessence, 1994.   2. Matthews TG. The anatomy of a smile. J Prosthet Dent 1978; 39:128–134.   3. Fradeani M. Esthetic Analysis: A Systematic Approach to Prosthetic Treatment. Chicago: Quintessence, 2005.   4. Bitter RN. The periodontal factor in esthetic smile design—Altering gingival display. Gen Dent 2007;55:616–622.   5. Blatz MB, Hürzeler MB, Strub JR. Reconstruction of the lost interproximal papilla—Presentation of some surgical and non-surgical procedures. Int J Periodontics Restorative Dent 1999;19:395–406.   6. Magne P, Magne M, Belser U. The esthetic width in fixed prosthodontics. J Prosthodont 1999;8:106–118.   7. Vig RG, Brundo GC. The kinetics of anterior tooth display. J Prosthet Dent 1978;39:502–504.   8. Passia N, Blatz MB, Strub JR. Is the smile line a valid parameter for esthetic evaluation? A review of the literature. Eur J Esthet Dent (in press).

  9. Fradeani M. Evaluation of dentolabial parameters as part of a comprehensive esthetic analysis. Eur J Esthet Dent 2006;1:62–69. 10. Gamborena I, Blatz MB. Current clinical and technical protocols for single-tooth immediate implant procedures. Quintessence Dent Technol 2008;31:49–60. 11. Holst S, Blatz MB, Hegenbarth E, Wichmann M, Eitner S. Prosthodontic considerations for predictable single-implant esthetics in the anterior maxilla. J Oral Maxillofac Surg 2005;63(suppl 2):89–96. 12. Kois JC, Kan JY. Predictable peri-implant gingival aesthetics: Surgical and prosthodontic rationales. Pract Proced Aesthet Dent 2001;13:691–698. 13. Blatz MB, Bergler M, Holst S, Block M. Zirconia abutments for single-tooth implants— Rationale and clinical guidelines. J Oral Maxillofac Surg 2009;67(suppl):74–81. 14. Yildirim M, Edelhoff D, Hanish O, Spiekermann H. Ceramic abutments—A new era in achieving optimal esthetics in implant dentistry. Int J Periodontics Restorative Dent 2000;20:81–91.

15. Jung RE, Sailer I, Hämmerle CH, Attin T, Schmidlin P. In vitro color changes of soft tissues caused by restorative materials. Int J Periodontics Restorative Dent 2007;27:251–257. 16. Jung RE, Holderegger C, Sailer I, Khraisat A, Suter A, Hämmerle CH. The effect of all-ceramic and porcelainfused-to-metal restorations on marginal peri-implant soft tissue color: A randomized controlled clinical trial. Int J Periodontics Restorative Dent 2008;28:357–365. 17. van Brakel R, Noordmans HJ, Frenken J, de Roode R, de Wit GC, Cune MS. The effect of zirconia and titanium implant abutments on light reflection of the supporting soft tissues [epub ahead of print 20 Jan 2011]. Clin Oral Implants Res. 18. Garber DA. The esthetic dental implant: Letting restoration be the guide. J Am Dent Assoc 1995;126:319–325. 19. Grunder U. Crestal ridge width changes when placing implants at the time of tooth extraction with and without soft tissue augmentation after a healing period of 6 months: Report of 24 consecutive cases. Int J Periodontics Restorative Dent 2011;31:9–17.

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20. Linkevicius T, Apse P, Grybauskas S, Puisys A. The influence of soft tissue thickness on crestal bone changes around implants: A 1-year prospective controlled clinical trial. Int J Oral Maxillofac Implants 2009;24:712–719. 21. Speroni S, Cicciu M, Maridati P, Grossi GB, Maiorana C. Clinical investigation of mucosal thickness stability after soft tissue grafting around implants: A 3-year retrospective study. Indian J Dent Res 2010;21:474–479. 22. Wiesner G, Esposito M, Worthington H, Schlee M. Connective tissue grafts for thickening peri-implant tissues at implant placement. Oneyear results from an explanatory split-mouth randomised controlled clinical trial. Eur J Oral Implantol 2010;3:27–35. 23. Esposito M, Grusovin MG, Maghaireh H, Coulthard P, Worthington HV. Interventions for replacing missing teeth: Management of soft tissues for dental implants. Cochrane Database Syst Rev 2007;(3):CD006697. 24. Fürhauser R, Florescu D, Benesch T, Haas R, Mailath G, Watzek G. Evaluation of soft tissue around single-tooth implant crowns: The pink esthetic score. Clin Oral Implants Res 2005;16:639–644. 25. Att W, Kurun S, Gerds T, Strub JR. Fracture resistance of single-tooth implant-supported all-ceramic restorations after exposure to the artificial mouth. J Oral Rehabil 2006; 33:380–386.

26. Nothdurft FP, Merker S, Pospiech PR. Fracture behaviour of implant-implantand implant-tooth-supported all-ceramic fixed dental prostheses utilising zirconium dioxide implant abutments. Clin Oral Investig 2011;15: 89–97. 27. Scarano A, Piattelli M, Caputi S, Favero GA, Piattelli A. Bacterial adhesion on commercially pure titanium and zirconium oxide disks: An in vivo human study. J Periodontol 2004;75:292–296. 28. Rimondini L, Cerroni L, Carrassi A, Torricelli P. Bacterial colonization of zirconia ceramic surfaces: An in vitro and in vivo study. Int J Oral Maxillofac Implants 2002;17: 793–798. 29. Degidi M, Artese L, Scarano A, Perrotti V, Gehrke P, Piattelli A. Inflammatory infiltrate, microvessel density, nitric oxide synthase expression, vascular endothelial growth factor expression, and proliferative activity in periimplant soft tissues around titanium and zirconium oxide healing caps. J Periodontol 2006;77:73–80. 30. Gamborena I, Blatz MB. Fluoresence—Mimicking nature for ultimate esthetics in implant dentistry. Quintessence Dent Technol 2011;34:7–23. 31. Benedict HC. A note on the fluorescence of teeth in ultra-violet rays. Science 1928;67:442. 32. Araki T, Miyazaki E, Kawata T, Miyata K. Measurements of fluorescence heterogeneity in human teeth using polarization microfluorometry. Appl Spectrosc 1990;44:627–631.

46 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

33. Lee YK, Lu H, Powers JM. Fluorescence of layered resin composites. J Esthet Restor Dent 2005;17:93–100. 34. Tani K, Watari F, Uo M, Morita M. Discrimination between composite resin and teeth using fluorescence properties. Dent Mater J 2003;22:569–580. 35. Sant’Anna Aguiar Dos Reis R, Casemiro LA, Carlino GV, et al. Evaluation of fluorescence of dental composites using contrast ratios to adjacent tooth structure: A pilot study. J Esthet Restor Dent 2007;19:199–206. 36. Monsénégo G, Burdairon G, Clerjaud B. Fluorescence of dental porcelain. J Prosthet Dent 1993;69:106–113. 37. Komine F, Blatz MB, Yamamoto S, Matsumura H. A modified layering technique to enhance fluorescence in glass-infiltrated aluminum oxide ceramic restorations: Case report. Quintessence Int 2008;39: 11–16. 38. Marchack BW, Futatsuki Y, Marchack CB, White SN. Customization of milled zirconia copings for all-ceramic crowns: A clinical report. J Prosthet Dent 2008;99:169–173. 39. Nik Mohd Polo Kinin NM, Wan Mohd Arif WI, Zainal Arifm A. Study on the effect of Y2O3 addition to the fluorescent property of dental porcelain. Med J Malaysia 2004;59 (suppl B):23–24. 40. Ferreira Zandoná AG, Kleinrichert T, Analoui M, Schemehorn BR, Eckert GJ, Stookey GK. Effect of two fluorescent dyes on color of restorative materials. Am J Dent 1997;10:203–207.

Determining the Influence of Flowable Composite Resin Application on Cuspal Deflection Using a Computerized Modification of the Strain Gauge Method Hamdi H. Hamama, BDS, MDS Assistant Lecturer, Conservative Dentistry Department, Faculty of Dentistry, Mansoura University, Mansoura, Egypt.

Nadia M. Zaghloul, BDS, MDS, PhD Associate Professor, Conservative Dentistry Department, Faculty of Dentistry, Mansoura University, Mansoura, Egypt.

Ossama B. Abouelatta, BEng, MSc Engg, PhD Associate Professor, Production Engineering and Mechanical Design Department, Faculty of Engineering, Mansoura University, Mansoura, Egypt.

Abeer E. El-Embaby, BDS, MDS, PhD Lecturer, Conservative Dentistry Department, Faculty of Dentistry, Mansoura University, Mansoura, Egypt.

Correspondence to: Dr Hamdi H. Hamama Conservative Dentistry Department, Faculty of Dentistry, Mansoura University, PO Box 35516, Mansoura, Egypt. Email: [email protected]

48 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

This study evaluated the influence of the application of flowable composite resin on cuspal deflection using a computerized modification of the strain gauge method. Forty sound extracted mandibular molars, which received a mesioocclusodistal slot preparation, were divided into two groups of 20 molars each based on the type of restorative materials used. Each group was further divided into two subgroups of 10 molars each relative to the application of flowable composite resin at cavity internal line angles. Cuspal deflection was measured using a new computerized modification of the strain gauge method. The mean cuspal deflection values (µm/m) and standard deviations were calculated and subjected to normality and homogeneity of variances tests. If they passed the tests, they were subjected to parametric statistical analysis (independent sample t test). The results showed that groups containing flowable composite resin exhibited higher cuspal deflection values than groups without flowable composite resin. The application of flowable composite resin at the internal cavity line angles increased cuspal deflection, possibly due to the material’s high volumetric shrinkage levels, which exerted more stress at the tooth-restoration interface. Further, the validity of the new computerized modification of the strain gauge method was proven by the agreement found between the output results and those of previous studies of cuspal deflection. (Am J Esthet Dent 2011;1:48–59.)

49 VOLUME 1 • NUMBER 1 • FALL 2011

Hamama et al

R

apid development of resin-based

line angles is one of the most contro-

dental composites is one of the

versial topics in dentistry. Some stud-

main characteristics of modern esthetic

ies support its use due to its stretching

dentistry. Resin-based composite is now

capability (ie, its low Young modulus

widely used as an alternative to amal-

of elasticity), which provides sufficient

gam in stress-bearing areas.1 Consider-

elasticity to relieve polymerization con-

ing the polymeric nature of composite

traction

resin, it has an inherited volumetric po-

some studies suggest that the appli-

lymerization

that

cation of flowable composite resin in-

leads to contraction stresses at the

creases contraction stresses due to the

shrinkage

restoration-cavity

property

interface.2

This poly­

stresses.5,10–14

In

contrast,

material’s high resin content.15–17

merization shrinkage has been reported

Cuspal deflection is a common bio-

to be one of the factors directly respon-

mechanical phenomenon observed in

sible for marginal leakage at the com-

teeth restored with composite resin. It

interface.3

results from the interactions between

The interaction of the polymerization

the polymerization shrinkage stresses

shrinkage stresses and the adhesive

of the composite resin and the com-

bond plays a large role in the long-term

pliance of the cavity wall.18 There are

function of a composite resin restora-

many methods to measure cuspal de-

tion. At sites where these stresses are

flection, including noncontact methods

higher than the bond strength between

(photography,19 microscopy,20,21 laser

the restoration and dental substrate, a

scanning,22

microgap will form, increasing the prob-

microcomputed

ability of postoperative sensitivity and

contact

recurrent caries.4,5 On the other hand,

interferometers,25

if the bond strength is higher than the

able

polymerization

stresses,

Because these methods depend pri-

the stresses will transfer to the cusps,

marily on measuring the difference

posite restoration–cavity wall

contraction

resulting in cuspal

deflection.2,6–8

A class of low-viscosity composite

and

three-dimensional

tomography23)

methods

differential

(strain and

and

gauge,6,24 linear

vari-

transformers26–29).

between precuring and postcuring values, they have not provided detailed

“flowable”

data regarding how cuspal deflection

composite resins, has been commer-

happens in relation to time. However,

cially introduced for restorative dentist-

the present authors introduce a modi-

ry. Flowability is regarded as a desirable

fication of the strain gauge method,

handling property because it allows the

which was developed in cooperation

material to be injected through small-

between the engineering and dental

gauge dispensers, thus simplifying the

teams of this study.

resins,

commonly

called

placement procedure and amplifying

This study was designed to evaluate

the range of applications suggested

the effect of the application of flowable

by the manufacturers.9,10 The effective-

composite resin on cuspal deflection of

ness of flowable composite resin as an

mesio-occlusodistal (MOD) composite

intermediate layer at the internal cavity

restorations. Cuspal deflection was

50 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Hamama ET AL

Table 1    Composite resin systems used in this study Material

Scientific classification

Trade name

Batch no.

Manufacturer

Tetric EvoCeram HB

J13387 J14049

Ivoclar Vivadent

Composite resin Restoration

Nanohybrid

Restoration liner

Nanohybrid

Bonding system

Filled, light-curing single component bonding agent for enamel and dentin in conjunction with the acid etch technique Etching gel containing 37% phosphoric acid

VOCO

Grandio Tetric EvoFlow

K15010

Grandio Flow

Ivoclar Vivadent VOCO

Excite

J25791 J25793

Ivoclar Vivadent

Total Etch

J25470 K20207

Ivoclar Vivadent

measured using the new modification

distance. The collected molars were

of the strain gauge method. The null

observed under magnification (×10) in

hypothesis was that application of flow-

a binocular stereomicroscope (LOMO

able composite resin does not increase

SF-100 Binocular Stereo Microscope,

the cuspal deflection of MOD compos-

MBC-10). Teeth with preexisting cracks,

ite resin restorations.

caries, or attrition were discarded. The selected molars were carefully cleaned using

Materials and methods

an

ultrasonic

scaler

(UDS-J

Ultrasonic Scaler, Ningbo Sunglow Imp & Exp) and then debrided with pumice

The materials used in this study are

(Americos Industries) using a rotary

listed in Table 1.

brush (Merssage Brush, Shofu). The molars were disinfected with 0.2% so-

Tooth selection and preparation

dium azide solution for 48 hours.30 To prevent dehydration, they were stored

A total of 40 sound extracted mandibu-

in physiologic saline for a period of no

lar molars were collected from the Oral

more than 1 month at 37°C until the

Surgery Department, Faculty of Den-

time of the test.

tistry, Mansoura University, Mansoura,

The molars were randomly divid-

Egypt. The patients were informed that

ed into two groups (20 molars each)

the voluntarily donated extracted teeth

based on the restorative material used

would be used for research purposes.

(Tetric EvoCeram or Grandio). Next,

To be included in the study, the mo-

each group was randomly subdivided

lars were required to have the following

into two subgroups (n =10) relative to

crown dimensions: 9-mm buccolingual

the application of flowable composite

distance and 10- to 11-mm mesiodistal

resin at the internal cavity line angles.

51 VOLUME 1 • NUMBER 1 • FALL 2011

Hamama et al

Each specimen received a nonreten-

connected to the gauge so that the

tive MOD slot preparation with the fol-

gauge constituted one-half of a Wheat-

lowing criteria: occlusogingival depth

stone bridge, with the other half internal

of 4 ± 0.3 mm without an axial wall and

to the strain gauge indicator. One layer

a buccolingual diameter of 3 ± 0.3 mm.

of the Excite universal bonding system

The remaining buccal and lingual cav-

was applied and cured using a light-

ity walls were measured using an elec-

curing

tronic digital caliper (MAX-CAL) after

Vivadent) at 800 mW/cm2 for 20 sec-

preparation for verification of the buc-

onds. The light intensity was checked

colingual diameter. The preparation

by

was carried out using a no. 59 carbide

Ivoclar Vivadent) prior to performing

bur (Komet Dental).

the test to confirm that the light inten-

unit

(Bluephase

radiometer

C8,

(Bluephase

Ivoclar

Meter,

sity was not less than 700 mW/cm2.

Cuspal deflection test

The teeth were restored with resinbased composite materials in shade

A 3-cm polyvinyl chloride tube was filled

A2 according to the following groups:

with acrylic resin (Rapid Repair, Dentsply) in the dough stage. The molar’s

• Group A: Flowable composite resin

roots were positioned at the tube center

(Tetric EvoFlow) was applied at the

and parallel to its long axis, leaving the

internal cavity line angles with a

crown and 2 mm of the root below the

small-gauge needle and cured for

cementoenamel junction uncovered to

20 seconds. Tetric EvoCeram was

accommodate the leads of the strain

inserted horizontally in increments.

gauge. A dental surveyor was used to

Each increment was approximately

verify that the tooth was parallel to the

2-mm thick and cured for 60 sec-

tube. After setting of the acrylic resin,

onds: 20 seconds from the occlusal

the parallelism of the cavity buccal

aspect, 20 seconds from the mesial

and lingual walls was confirmed by the

aspect, and 20 seconds from the

same surveyor.

distal aspect.

All prepared cavities were etched

• Group B: This group was similar to

using Total Etch for 15 seconds accord-

group A, except it did not receive

ing to the manufacturer’s instructions.

flowable composite resin prior to in-

Two precision strain gauges (KFG-2N-

sertion of Tetric EvoCeram.

120-C1-11L1M2R, Kyowa Electronic

• Group C: Flowable composite resin

Instruments) were attached to the buc-

(Grandio Flow) was applied at the

cal and lingual surfaces of each unre-

internal cavity line angles with a

stored specimen and bonded with

small-gauge needle and cured for

epoxy adhesive resin (Strain Gauge

20 seconds. Grandio was inserted

Cement, Kyowa Electronic Instruments)

horizontally in increments. Each in-

to the middle third of the cavity’s exter-

crement was approximately 2-mm

nal buccal and lingual walls (Fig 1). The

thick and cured for 60 seconds: 20

leads of the strain gauge indicator were

seconds from the occlusal aspect,

52 THE AMERICAN JOURNAL OF ESTHETIC DENTISTRY

Hamama ET AL

Personal computer Strain indicator program AD card Tooth fixation 3-channel amplifier Curing unit

a Fig 1 (above)  Buccal view of the strain gauges bonded to the middle third of the external cavity wall. Fig 2a to 2c (right)  The strain measurement system.

b

c

20 seconds from the mesial aspect,

The present study is based on the data

and 20 seconds from the distal as-

range, ie, the difference between the

pect.

maximum and minimum strain values.

• Group D: This group was similar to group C, except it did not receive

However, the data curves will be analyzed in detail in future studies.

flowable composite resin prior to in-

Strain measurement system

sertion of Grandio. During

polymerization,

the

strain

The strain measurement system con-

gauge recorded the changes in volt-

sisted

age signals, which were then amplified

circuit (Metrology Lab, Faculty of En-

by the recording system. The ampli-

gineering, University of Mansoura), an

fied signals were transferred using an

AD card, and a personal computer with

analog-to–digital converter (AD) card

the Strain Indicator Program (SIProg),

to a specially designed computer pro-

which was designed for this study by

gram (SIProg) for analysis. The results

Dr Abouelatta (Fig 2).

of

a

three-channel

amplifier

appeared as a curve between the time

SIProg was fully written in house us-

(seconds) and strain values. These

ing Matlab packages. The main inter-

readings for the Wheatstone bridge

face is shown in Fig 3. It consists of

are directly proportional to the internal

a title bar, menu bar, measuring infor-

cuspal deflection of the buccal and

mation panel, processing panel, option

lingual cusps of tested specimens.31

panel, and display area. To calibrate

53 VOLUME 1 • NUMBER 1 • FALL 2011

Hamama et al

Title bar Menu bar Display area

Fig 3   Graphical user interface of the Strain Indicator Program (SIProg).

the strain measuring system, specific

microstrain (με) values were applied

statistically significant when P < .05 with a confidence level of 95%.

on a sample tooth. The strain measurements were recorded using P-3500 Strain Indicators and SB-10 Switch and

Results and discussion

Balance Units (Vishay Measurements Group). The same values were record-

The independent sample t test showed

ed by the system in millivolts. A graph

a statistically significant difference (P