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MANT]AL FOR

DE NTA L TE CHNICIA N S rULCA] VI T E t]\'

J. A. SALZMANN, D.D.S. Chairnran, Conrmittee on Coursesfbr Dental Technicians and Head of Dental Service,New York City Vocational Schools: Editor, New York Journal of Dentistry : author of Principles and Praclice of Public Healtl Denristrl

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CONTENTS PAGE

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D E N T A L LABORATORY M E C H A N I C S

INTRODUCTION DEN-S~IL LAROR.ITORY MECHANICS is an art which deals with the construction of prosthetic (artificial) appliances for the replacement of teeth and gums lost through disease or accident. As an occupation it fills an important human need by corltributing to the health and happiness of mankind. I t has often been pointed out that the active demand for dental service includes only twenty to twenty-five per cent of the public, whercas the actual need for such service exists in between ninety to ninety-five per cent of the population. Whatever the reason for this condition, certainly the tendency at present is toward greater interest in Public Health, as shown by child health programs, the Social Security Act of the Federal Government and the public health programs of the various states and municipalities. Social legislatior1 now being considered and adopted by the different states also brings with it a greater interest in the physical welfare of the population. These activities indicate that the potential need for dental services will eventually be translated into an active demand. Aided by the services of the dental technician, the dentist is enabled to devote more of his time and attention to work which must actually be performed in the mouth of the patient. I t can be seen, therefore, that opportunities for employment of persons trained in dental laboratory work are bound to be increased. T h e field of the dentist and that of the technician, while closely related, are none the less very well defined. While the dental technician may be trained to assist the dentist in the construction of prosttl~eticappliances, his approach is, of necessity, from a technical htnndpoir~t. T h e dentist, on the other hand, because of his training i r l the basic biological and physical sciences is alone equipped to ;lhhunlc responsibility to the patient. I n order for the technician t o sh:lrc this responsibility directly he would have to be trained in I I I ( . :LCOI-cn~cntiollcd scicnccs, including graduation from a dental .t~ (cross swtiol~).

44

M A N U A L ]'OR

I)I1-e\\iol1 around teeth, being especiallq careful to do so around 1~)1,1tc(1 tectli. (1:ig. 59.) C. Icntal I t c ~ n sof lntercst I'ublishing Co., 1c)31.. 2.

ARTICULATING TECHNIC-11

UNIT NO. 8 (Continued) A R T I C U L A T I N G TECHNIC-I1

I

119

to simulate the jaw movements ordinarily produced in chewing food by the individual patient. All measurements for adjusting should be provided by the dentist. The technician should know how to insert the casts and transfer the face bow relationship and measurements obtained by the dentist from the patient's jaws. (Fig. I 19.) The adjustable articulator makes it possible to maintain contact of the upper and lower teeth during various limited movements of the lower jaw as in chewing.

Adaptable or adjustable articulators, also known as anatomical articulators, have been devised so that the instrument may be able to imitate the movements of the jaws of the patient by moving the extension arms of t h e articulator. T h e adaptable articulators provide for the transference of certain measurements which are obtained .by the dentist from the patient's own jaws. I n the plain line or movable arm articulators there are no provisions for adjustment to conform to the sidewise and other jaw movements. T h e main reason for using an adjustable articulator is to provide a guide for the arrangement of the teeth in such a manner that the teeth may remain in contact when the lower jaw is moved about within certain limits as in chewing food. I n short, by means of an adaptable articulator we can achieve what is termed a balanced articulation or intermeshing of the teeth of the upper and lower dentures. Balanced articulation of dentures makes them more stable in the mouth (this helps in chewing), it eliminates undue changes in the gums and other tissues on which the dentures rest and adds to the comfort of the patient.

Process o r Principle : No. 14. Mounting on anatomical (adjustable) articulators. a. Face bow transfers. b. Mounting edentulous casts. Project o r Jobs: (To be performed by the learner.) JOB No. 38: Mount two sets of edentulous casts on Gysi or Hanau Articulator. NOTE: (Read the entire Unit carefully before beginning work. Consult the glossary for definitions of new words.) Job Application: Anatomical or adjustable articulators are appliances that may be regulated to produce lateral and other movements similar to those of the human mandible. This instrument makes it possible to arrange the teeth so that they remain in contact during these movements, resulting in more stable dentures. Vocational Information: The theory underlying the usc of adjustable or anatomical articulators is that the articulator can bc made 118

Note: By adjusting the face bow over the condyles (in front of the ear holes) at the junction point between the lower jaw and the upper jaw and fixing the biteplates to the face bow, the dentist obtains the relationship of the jaws to the condyles (the junction point of the jaws). This relationship is transferred to the articulator by the technician and aids in obtaining a balanced occlusal relationship of the teeth which are later arranged on the denture bases.

Tools and Equipment: Adaptable articulator (Gysi or Hanau), plaster bowl, plaster spatula, plaster knife, face bow. (Fig. 120.) Materials : Plaster, water, vaseline. Procedure: (Follow operations in the order presented here.) CAUTIONS: a. Be szcre the articulator is in centric occlzwion before beginning to mmnt casts. b. Release the condyle bars evenly to meet the face bow adaptor tugs.

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MANUAL FOR DENTAL TECHNICIANS

c. Make sure that occlusal planes of the biteplates are parallel with lugs No. I r and point of pin No. 7 (Gysi Articulator.) d. T o prevent plaster sticking to articulatm and to facilitate removing the casts, vaseline should be applied where indicated. I . W h e n Using t h e Gysi Simplex Articulator (Fig. 120) proceed a s follows: A. T o Mount Casts Without the Use of the Face Bow: I. Place the straight incisor guide pin (Figs. 120 and 122) in the

ARTICULATING TECHNIC-I1

I21

4. Place an elastic band or a cord about the setscrew on the straight incisor guide point and in the notches on the outer sides of the vertical part of the frame (Fig. 122s). This will establish the correct occlusal plane. 5. Place a mass of soft wax on the lower extension arm and force the lower cast down over it until the occlunl place of the biteplate is level with the elastic band or cord and the median line of the biteplate touches the tip of the incisor guide. Adjust the casts so

Courtesy Dentists' Sufifily Co., New Yosk

FIG. I zo. G Y ~SIMPLEX I ARTICULATOR Note: This articulator reproduces average movements of the mandible. It is an improved movable arm articulator and is adaptable to various jaw movements within certain limits.

sleeve on the upper extension arm, keeping the top of the pin level with the top of the sleeve. 2. Place the incisal guide (Fig. 122C) on the pin, with setscrew, in the depression of the pin and the point directed backward to the median line. 3. Extend the median line mark on the front of the upper cast vertically upward to the top of the cast; make a similar mark vertically upward on the rear of the cast, starting from the median suture on the palatc. Draw a straight linc across the top of the cast, connecting these lines. This is the median line of the cast.

that the median line mark on the upper cast will be below the median line of the upper extension arm. Attach the upper cast to the upper extension arm, then invert the articulator and attach the lower cast to the lower extension arm. (Fig. 12I.) NOTE: T h e Snow Student's Articulator (Fig. 124) n ~ d yalso be used for this purpose. Directions for using are similar to the foregoing. B. T o Mount Casts with the Face Bow. (Figs. 1 2 2 and 123.) I . Place the curved incisor guide pin (Fig. 1221) in the sleeve on the upper extension arm of the Gysi Simplex Articulator, the top of

I22

MANUAL FOR DENTAL TECHNICIANS

ARTICULATING TECHNIC-11

123

the pin should be level with the top of the sleeve. T h e end of tl pin should touch the incisal incline on the lower extension arm. 2. Adjust and lock each condyle bar of the face-bow so that 01

T h e casts a r e related by means of the face bow and sealed to each other in the position indicated by the jaw relationship of the patient. B-Incisor guide pin set supporting block to support the front of in anterior supporting block. &Anterior stem connecting the horseshoe the face bow when mounting casts. F-Slip-joint plate, between the biteplates, with the face bow. E-Horseshoe plate connected to the slip-joint (F) holding the biteplates in proper relationship to the face bow. lock trays, guide pin incline. M-Bite I-Curved incisor guide pin. U-Incisor on vertical support of articulator. Dlocking the biteplates together. A-Notch of condyle b a r to fit Snow face bow. R-Lock nut for condyle bar. P-Slip-joint over face bow adapters. N-Face bow adapter of the articulator.

FIG. I 2 2 . GYSISIMPLEX ARTICULATOR Parts and Accessories I articulating frame, in two parts, I upper and I lower extension arm, I straight incisor guide pin ( B ) . A n incisor guide ( C ) for mounting casts on the articulator when the face bow is not used. A snow face bow ( D ) for mounting casts on the articulator in correct relation to the articulating joint (the condyles). Condyle bar ( P ) with slip joint for adjusting over the face bow adapters ( N ) of the articulator. ( R ) is the lock nut for the condyle bar. A horseshoe plate (E) and slip joint stem (F). T h e horseshoe plate is used with the incisor path marker to obtain correct bite relationship. T h e slip joint stem connects the horseshoe plate with the face bow. A mouth piece for the face bow ( H ) used only when squash bites a r e taken on partials. A curved incisor guide pin ( I ) used only when mounting casts with the face bow. A n incisor path marker (K) used with the horseshoe plate for determining correct bites. A n interior supporting block (L) to support the front of the face bow when mounting casts. T w o bite lock trays (M) for locking biteplates together. T h e two face bow adapters of the articulator ( N ) . A n incisor guide incline ( U ) .

A Gysi Simplex Articulator ( A ) composed of

and one-half divisions on the condyle bar arc exposed external to the locknut slccve on the face bow. 3. Set thc casts between the uppcr and lower extension arms of thc articulator and spring the condyle bars over the face bow adapters of thc at-ticuliltor (17ig. 123).

FIG.I 24. SNOW'SSTUDENTARTICULATOR Note: T h i s is a good articulator to use prior to undertaking the arrangement of teeth on the regular adaptable articulators.

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MANUAL FOR DENTAL TECHNICIANS

ARTICULATING TECHNIC-I1

127

3. Principles underlying different adaptable articulators. 4. Advantages of adjustable articulators in partial cases. 5. Principles of "face bow transfer." Questions : I . W h y is the articulator adjusted to centric occlusion before mounting casts? 2 . Why should the condyle bars on the face bow be released evenly when adjusting them to the articulator? 3. Why should the occlusal plane of the biteplates be parallel with the lugs No. I I and the point of pin No. 72 (Fig. 125.)

Note: T h e upper cast has been attached to the upper extension arm. The face bow has been removed and the Qrticu~atorhas been turned upside down. The lower cast is now attached to the lower extension arm of the articulator.

pin No. 10. Invert the articulator and apply plaster as in the upper. Wait until the plaster has set before turning the instrument on its base. (Fig. 127.) 8. T h e articulator is now set according to the specifications which the dentist obtained from the patient. T h e sagittal condyle controls are set by releasing lock No. 2 and setting sagittal condyle path indicator No. 2 2 at the figure on the degree plate No. 3 as specified by the dentist. Lock nut No. 2 is then locked. This is done on the right and left sides. T h e arrangement of the teeth is the next step. (Fig. 128.) Supplementary Assignment: learner.)

(Information to be obtained by the

Other types of adjustable articulators on the market. (Figs. 129 and 130.) o. Advantages and disadvantages of: v;~riousstyles of: ndjustahle articulators. I.

Coi l ~01' u t . thc I ~ L I I ~ ~ : teeth? III ,:. \\'h;~t:[I-c tlic n:ltncs : L I I ~ I~I L I I ~ ~ ~ > C ,uf I - ;it.titici;il teeth.; 3. \\'hat are the ~ ~ ; u l ~:111ci c s Ioc.:~tior~s ol' thc \.aric)us crown surfaces? 4. H o w rllny the tooth crow11 surf:lces bc divided? 5. Describe the physical appearance of the crowns of the individual teeth. 6. What questions must be answcred in rccogr~izingindividual teeth.; 7. Give divisioils of an artificial tooth. 8. W h a t are the main typal forms of artificial teeth? 0. W h a t d o we mean by the following: Cusp; tubercle; ridge; fossa; sulcus; groove; interproximate space; diatoric; mcsial ; distal; buccal; l i ~ l ~ u a pajatal; l; incisal; occlusal; gingival; axial; transverse ridge; cervical; point-angle; line-angle; crest; crown; collar of tooth; ridge-lap; shut; bite? Job Appraisal : I. Can you recognize each tooth, tell which tooth it is, which jaw, and the side of the jaw to which the tooth belongs? 2. DO you know the names and angles of the various tooth surfaces? Ii I ~ I ; ~ ; . R E N C E S(Books : for Additional Information.) 1 . R J ~ I ~ upper second bicuspids a r ~ d first rr~olars. Slii/i/rrr rp[i( I ' F rI~ouldbe lefi b e l w e ~ nt h e lower first molars (iilrl /hc*/owe;- .r, rot~tlbiruspiils anrl, if possibl~,brtzrlfvw tl~c, / o ? ~ v , ]it ) \ / /)/I//.rpjrLs rit/(/ i / i ( ~ ~u.\ph/s.

>

I54

ARRANGING ARTIFICIAL T E E T H

MANUAL FOR DENTAL TECHNICIANS

lower biteplate when viewed from the front. T h e teeth should incline downward and forward when viewed from the side. T h e incisal edges should be in contact with, and follow, the contour of the outer edge of the occlusal surface of the lower biteplate. T h e distal angle of the centrals should incline slightly inward and begin the curvature of the dental arch. Attach the centrals with wax on heated wax spatula. (Fig. 143.1

h. T h e compensating curve to which the occlusal surfaces of the lower molars and the second bicuspids are set should be governed by the curvature of the posterior portion of the lower ridge. If the occlusal surfaces of the lower molars are set parallel to the uptwned posterior section of the ridge, the force applied to the ridge through the teeth i n the act of chewing will be at right angles to the surface of the ridge alzd will hold the lower delzture rigidly in place. i. A lower ridge that has a great curve m.11 call for a correspondingly great curvature in the arrangement of the molars and bicuspids. j. I n many cases a compensating curvature great enough to stabilize the lower denture may have a tendency to create a forward, dislodging pressure on the upper denture, if the upper has no curvature of the alveolar ridge. For such cases the compensating curve must be modified so that it will take an inclination which is halfway between the fiat character of the upper alveolar ridge and the steep slope of the lower alveolar ridge. k. T h e lower cuspids should glide against the upper cuspids when the extension arms of the articulator are moved sidewise. T h e lower cuspids should not touch the upper laterals when the extension arms of the articulator are moved sidewise. 1. W h e n the dentures are in centric occlusion ( t h e articulator extension arms are at rest), the lower incisors should not be in contact with the opposing upper incisors. m. T h e danger of breaking the incisors in using the denture zen'll be eliminated if the foregoing instructions are observed in arranging the teeth. Errors that may become evident in the filzished dentures are corrected by the dentist who grinds the teeth w'th a stone when the dentures are examined and fitted in the mouth of the patient.

I. Arranging Upper T e e t h : NOTE: Arrange upper teeth in edentulous cases as follows: (The same method should be followed for all uppers.) r . Seal the biteplates to the casts, using sticky wax on hot spatula. Cut out sufKcient wax on the upper biteplate and attach the upper central incisor teeth against the alveolar ridge of the upper baseplate, to.the right and left of the median line. The incisal edge, should be parallel with the outer edge of the

I55

FIG. 143. B-Labial

2.

,-

UPPERRITEPLA.I.E CUT 0 ~ 1 1.0 . ALLOWF O R PLACING O F LEFT UPPERCEN.I-RA+( INCISOR view. Note: T h e incisal edge is parallel with the edge of the upper biteplate. C-Distal view. Note: Inward inclination of tooth.

Cut out the biteplate and set the upper laterals distal to the centrals. T h e incisal edges of the laterals should be threefourths of a millimeter above the level of the incisal edges of the centrals. T h e long axis should incline distally when viewed from the front and downward and forward incisally when viewed from the side. (Fig. 144.) T h e necks of the upper laterals should be less prominent (they should be set inward) and closer to the alveolar ridge than those of the upper centrals. The incisal edges of the laterals should continue the curvature of the dental arch along the outer cdgc of the occlusal surface of the lower biteplate. Attach the laterals with wax on heated wax spatula.

1 5 ~

MANUAL FOR DENTAL TECHNICIANS

ARRANGING ARTIFICIAL TEETH

I57

3. Cut out the biteplate and set the upper cuspids distal to the upper laterals. T h e incisal tips should extend just slightly below the outer edge of the lower biteplate. T h e labio-axial ridge of the cuspid is the dividing line between the labial and buccal aspects (anterior and lateral views) of the denture.

B-Labial view. Note: T h e tooth is raised upward from the edge of the biteplate, while the long axis of the tooth inclines somewhat distally, the rnesio-incisal angle is nevertheless longer than the disto-incisal angle. C-Distal view of the upper lateral incisor. Note: T h e inward inclination at the neck of the tooth is greater in the lateral than in the central.

T h e mesial half of the labial surface of the cuspid should be set to face the lips while the disto-labial half faces buccally. T h e long axis of the cuspid should incline slightly distally from the incisal tip. T h e incisal edge should follow the curvature of the outer edge of the lower biteplate. Attach the

FIG. 145. METHODOF SETTINGCUSPID B-Labial view. Note: T h e cuspid is inclined slightly distally from the incisal on its long axis. C-Distal view. Note: T h e cuspid has less inward inclination at the neck than the lateral. D-Incisal view. Note: T h e teeth are set so that they carry out the occlusal atch. T h e incisal tip of the canine is slightly lower than the central.

cuspid with melted wax on heated wax spatula. T h e necks of the cuspids should be more prominent than those of the laterals. (Figs. 145, 146 and 147.) 4. Set the upper bicuspid teeth to follow the general outline (shown in Fig. 148). Cut out sufficient wax on the biteplatc to allow the insertion of each of the teeth to follow.

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MANUAL FOR DENTAL TECHNICIANS

ARRANGING ARTIFICIAL

TEJTI"I'

I59

6. T h e upper second bicuspid is set similarly to the upper first bicuspid excepting that both the lingual and buccal cusps touch the occlusal surface of the lower biteplate. (Figs. 148 and 150.) 7. Using a straight edge, test the position of the buccal surfaces of the bicuspids in relation to the cuspids. T h e straight edge should touch the buccal ridges of the cuspid and the first and First Second First Bicuspid Bicuspid BIolar

Second Molar

I n arranging Trubyte Posteriors, look for the small raised dots on the mesial side of the diatoric surface. One dot on a bicuspid designates the first bicuspid; two dots, the second bicuspid. One dot on a molar designates the first molar; two dots, the second molar. As these dots are always on the mesial side of the tooth they also show at a glance whether the tooth is right or left.

Courtesy Dentists' Sut.ply Co., dVcw York

After

Clafip

Nofe: T h e compensating curve can be made to follow the template. Where the template is not used, follow the instructions provided in Unit No. 10.

5. T h e upper first bicuspid should be set so that the buccal cusp touches the occlusal surface of the lower biteplate while the lingual cusp does not quite touch it. T h e tooth viewed laterally should bisect the line on the lower biteplate that folridge. (Figs. 148, 14') lows the crest of the l o w ~;~lvcolnr ~and 150.)

A-First bicuspid, buccal and distal views. B-Second bicuspid, buccal and distal views. C-Buccal relationship of the cuspids and bicuspids. Note: T h e white lines show the relationship of the bucco-lingual aspect of the teeth to the straight edge. T h e white lines are parallel and bisect the alveolar ridge.

second bicuspids. Rotate the bicuspids on their long axis so that lines through their linguo-buccal dimensions follow the line c in Fig. 150, with relation to the straight edge. 8. Attach the upper first molars so that the long axis when viewed from the buccal aspect appears as shown in Figs. 148 and 151. T h e disto-buccal cusp of the first molar should be raised slightly off the lower biteplate.

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MANUAL FOR DENTAL TECHNICIANS

13. T h e lower second molar is set distally to the first molar in a manner similar to that employed in setting the first lower molar. T h e second lower molar should occlude with the distal cusp of the first molar and most of the occlusal surface of the upper second molar. 14. With wax and heated spatula attach the lower second bicuspid to the lower baseplate. T h e lower second bicuspid should

ARRANGING ARTIFICIAL TEETH

163

16. Apply a triangular piece of pink wax to the crest of the anterior portion of the lower ridge from canine to canine. Set the lower anterior teeth in the following order: the lower cen- . trals on both sides of the median line corresponding to the median line formed by the upper centrals; place the lower

Note: T h e long axes of the incisors and laterals are parallel but the cuspids incline distally at the gingival margin.

FIG. 1 5 3 . RELATIONSHIP OF UPPERA N D LOWER BICUSPIDSA N D CUSPIDS A-Detail

of articulation of upper cuspid and first bicuspid and lower first bicuspid. B-The lower bicuspids and cuspid have been set in position.

Note: T h e relationship to the alveolar ridge and inclination of each tooth varies although the incisal edges are all on the same line.

occlude with the distal incisal incline of the upper first bicuspid and the mesial incisal incline of the upper second bicuspid. (Fig. I 53.) 15. Set the lower first bicuspid mesial to, and in the same manner, as the lower second bicuspid. T h e lower first bicuspid should occlude with the distal incisal incline of the upper cuspid and the mesial occlusal incline of the upper first bicuspid. (Fig. 154.1

Note: T h e lower anterior teeth are set inward at the occlusal edge and are out of I1ontnct with the lingual surfaces of the upper anterior teeth. T h i s is known as the swcr-jet. T h e lower anteriors should be slightly higher than the incisal edge of the \lppcr anteriors. This is known as the over-bite and is equal to the depth of the cusps of the molar teeth. See Fig. 150.

lateral incisors distally to the lower laterals. Set the necks of the lower incisor teeth directly over the lower ridge. Set the necks of the lower cuspids anterior to the ridge. (Figs. 154, 155 and 1-56.) I 7. T h e upper and lower teeth at the bicuspids and molars should be in full contact when the articulator is closed in centric occlusion.

164

MANUAL FOR DENTAL TECHNICIANS

ARRANGING ARTIFICIAL TEETH

18. A sheet of softened basewax when closed between the upper and lower dentures should show bitemarks. (Figs. r 57, I 58 and 159.)

I-Cross

section showing cuspal relationship. H-Shows the distance of the cuspal height. G-Occlusal view of bicuspids and molars in Trubyte Teeth.

A-Plaster attaching lower cast to articulator extension arm. B-Lower cast. CLower basewax. D-Upper basewax. E--Upper cast. F-Plaster attaching upper cast to extension arm of articulator.

Note: T h e white markings show the occlusal contacts between the upper and lower teeth as seen in a piece of modeling compound which had been softened and pressed between an upper and lower set-up o f Trtthyte Teeth.

111. Arranging Teeth on Partial Dentures: NOTE: T h e clasps used to retain partial dentures are not included in this Unit since making clasps involves advanced procedures not described here. Arrange the necessary teeth in a manner similar to that followed in arranging full dentures. Teeth

in partial dentures are often set directly to the cast without any labial wax on the denture base. I t rn-dy be necessary to grind the ridge-lap portion or mesial and distal surfaces of certain teeth in order to fit them closer to the gum or the natural teeth. When grinding porcelain teeth proceed as follows: I. Mount carborundum wheel on lathe chuck. 2. Cut a small strip of articulating paper. (Paper coated with coloring which comes off on an object when pressed against it.) Place the articulating paper on the gum over the place where the tooth is to be fitted (Fig. 160). 3. Press the tooth against the paper and rub the tooth slightly against the paper. This will indicate on the tooth, by means of the coloring rubbed off the articulating paper, where the

I 68

MANUAL FOR DENTAL TECHNICIANS

ARRANGING ARTIFICIAL TEETH

169

tooth is to be ground in order to fit it closer to the gum (Fig. 160). 4. Holding the tooth between the index finger and thumb of the right hand and using the fingers of the left hand to steady the right hand, bring the marked portion of the tooth to be ground against the revolving carborundum wheel (Fig. I 61) . 5. Expose the part of the tooth to be ground so that the fingers holding the tooth do not come into contact with the revolving wheel. 6. Repeat marking the tooth on the articulating paper and grinding until the tooth fits closely against the gum. Do not keep the tooth too long against the revolving carborundum wheel. Doing so overheats the tooth and may cause it to crack. NOTE:There are many types of modified teeth on the market. (Figs. 162, 163, 164, 165, and 166.

Courtesy Universal Dental Co., Philadelphia, Pa.

FIG. 164. DR. FRENCH'S MODIFIED POSTERIOR TEETH

Questions : I. Why are specific principles followed in arranging teeth? 2. What principle is followed in setting up upper anterior teeth? 3. What principle is followed in setting up upper posterior teeth? 4. Why is it advantageous to set up the lower first molars first in setting up lower teeth? 5. Why should the teeth be firmly attached to the base? 6. How far is the basewax extended? 7. What principles are followed in setting up the following teeth as regards their relationship to each other? a. The upper central, lateral and cuspid?

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MANUAL FOR DENTAL TECHNICIANS

ARRANGING ARTIFICIAL TEETH

,

171

*-.,

Courtesy Idcnl T o o t h Mfg.Co., Cambridge, Mass.

FIG.166. TRUE CUSPPOSTERIORS Note: Modified posterior teeth.

Manufactured for purposes of increasing stability of dentures during mastication.

FIG.165. UJ-'PER AND

DENTURES \\'ITH DR. FRENCH'S MODIFIED POSTERIORS ~A~~~~

Note: T h e inclined planes have been eliminated in order to prevent throwing the teeth "or~tof gear" when the dentures settle. At the same time, a sharp edge ant1 food escapes were added to increase masticating efficiency.

b. The upper cuspid, first bicuspid and second bicuspid? c. The upper first and second molars? d. What principle governs the relationship of the upper bicuspids to the upper molars? 8. Why is a plain line articulator inefficient as an instrument for setting up artificial teeth? Job Appraisal : I. Are the uppers set according to the lower biteplate? 2 . Are the lowers set according to the upper biteplate? 3. Do the teeth interdigitate (occlude) properly? 4. Can you arrange the upper and lower teeth in 60 minutes (average) ? Supplementary Assignment: (Information to be obtained by the learner.) I. Makes of teeth available on market. 2 . Modified posteriors, types. 3. Pinless teeth. 4. Anatomical arrangement of teeth. 5. Staining processes.

172

MANUAL FOR DENTAL TECHNICIANS

6. Modifications of tooth arrangement. 7. Grinding and polishing of teeth. 8. Advantages, disadvantages, indications and contra-indications of different types of teeth. REFERENCES: (Books for Additional Information.) I . Trubyte Compend (Fifth edition). XT

2.

3. 4.

5. 6.

RELATED INFORMATION:

U N I T NO. 10

ARRANGING ARTIFICIAL TEETH

Dentists Supply Co., New York,

V

Principles of Selection and Articulation. Dentists Supply Co., New York, N. Y. Nichols, I. G.: Prosthetic Dentistry. St. Louis: C. V. Mosby Co., 193I . Frahm, F. W.: T h e Principles and Technics of Full Denture Construction. Brooklyn: Dental Items of Interest Publishing Co., 1934. Turner, C. R. and Anthony, L. P.: American Textbook of Prosthetic Dentistry. Philadelphia: Lea & Febiger, I 93 2. Swenson, M. G.: Outline of Full Denture Prosthesis, New York: New York University Press, I 93 2.

CHART OF NORMAL INDIVIDUAL TOOTH POSITIONS

Labio-lingual

MesiO-distal

Rotational

w "u,E ($ni, position)

CENTRAL

Labial face is Perpendicular parallel to profile line of face which is USUally perpendicular I

2

Parallel with On the cuwe of arch plane

3

4

To the lingual To the distal Distal half to- Above the a t the neck a t the neck tated to the plane lingual o r UPPER LATERAL mesial to the labial 8 6 5 7

UPPER

From perpendic- Very slightly Distal half of Tip on plane ular to out at to the distal l a b i a1 f a c e and not bethe neck, ac- at the neck pointing in di- low it rection of poscording to the terior arch gender of the face 9

10

To the lingual Perpendicular LOWER at the neck CENTRAL 14 13 Perpendicular LOWER ~ATERAL

18

Labio-lingual and me$?-distal PoS1'On

II

12

Parallel to the On the plane curve of the arch 16 IS

According to the t y p e of t h e a r c h ; in t h e square, the centrals are very little forward of the cuspids; in the tapering, they are considerably forward of the cuspids; and In the ovoid arch, the centrals are more forward than in the s uare arch and less than in the tapering.

Slightly to the Distal to the On the plane distal lingual slightly I7 21 20 I9

Out at the neck To the distal Distal half of Tip on the a t the neck labia! face plane and I.OWER polntlng i n ?ot above CUSPID directipn of ~ t . posterlors 22

23

24

C o ~ ~ r l a sofy Dr. Merrill G. Swenson, Professor of Prosthetic Dentistry,

~lntry.

173

25

New York University, College of Den-

I74

MANUAL FOR

DEN'rAL

TECIINICIANS

Curve of Spee: This is an imaginary curve which begins at the incisal tip of the lower front teeth (incisors) and passes through the top of the cusps (occlusal elevations) of the posterior teeth. Compensating Plane: T h e compensating plane is a mechailical I t is that arrangement of the teeth whereby the contact is maintained between the upper and lower artificial dentures when the teeth are moved, as in chewing. T h e plane must be in harmony with the excursions of the condyle. Efficiency of Artificial Dentures: Sound human teeth in healthy gums can exert a biting power of about roo pounds and a crushing strength of about 200 pounds. T h e human teeth are held individually in the bony sockets of the jaws. Artificial teeth mounted on artificial dentures are easily displaced. They can exert only about I 5 to I 8 pounds pressure under favorable conditions. Modified Teeth: Bicuspids and molars have been designed especially to increase stability of dentures. During the past few years, bicuspids and molars have been modified as the result of various theories so that they bear little resemblance to human teeth. (Figs. 162, 163, 164, 165 and 166.)

U N I T NO.

11

DENTURE WAXING TECHNIC After the technician arranges the tectli 01; the trial base, he proceeds to triin, ~ilould:tnd carve the wax so th;tt he has n matrix or pattern of the base of tlle finished denturc. T'lle wax p;lttcrn, u~llich togctl~crwith the teeth is known as the waxed case or trial denture, is tried in tllc patient's ~ n o u t hby tile dentist. Since tlie pattern or t r i d denture is madc o l w a x i t can bc changed easily, wllcn necessary to change the arrangement o l the teeth or tlie wnxing to any degree. T h e dentist obscrves at this time tllc effect of the denture on the appeamnce of the patient. If the patient's face looks too full, the dentist riiay reduce the thickness of tllc wax on tllc bucc,tI and labial surfaces of the denture. Contrnrily, i f tllc denture docs not fill out the p~cticnt's face the dentist 1113) add \vax to the buccal and 1:lbinl surf & ~ . 'I'hcrc are many re.lsons wily the waxing of tllc denture bnsc rnust be accur;ltely perforincd. 7'hcse reasons will bc discussed in the following pilges.

Process or Principle : No. I 7: Waxing Vulcanite Ilentures. a. IVaxinx ftdl uppcrs and Lo;r.el-s. b. ?4'axinX partial rases. Project or Jobs: ( T o be performed by the lear~ler.) J O B NO. 49: Wax an edentulous upper and lower ( a wax denture base without artificial teeth). Jon No. 50: \Tax two full upper and lower dentures on baseplate bases. J O B No. 51: Wax two full upper and lower dentures on basewax bases. Jon No. 52: U7ax six partial dentures. NOTE: (Read the entire Unit carefully before beginning work. Col~sultthe glossary for definitions of new words.) Job Application: After the teeth are arranged wax is applied over thc dcntul-e base, making a matrix which is later replaced by vul( ; i l ~ i t r .01- sonic other pcrmanent denture base material. When the w:ising is completed, the dcriture is rcady for- trial in the patient's I I I O L I I 11 I)y thc dcrltist. '

I

,

1 7 ~

MANUAL FOR DENTAL TECHNICIANS

Vocational Information : Waxing should be done carefullv and u neatly as the permanent denture base duplicates the wax matrix. Faults in waxing' are, therefore, repeated in the permanent denture. Waxing on the buccal and labial surfaces should be modified by the dentist to suit the facial appearance of the patient. Pits in the wax should be eliminated and all teeth should be waxed securely. Tools and Equipment: Bunsen burner, wax spatula, roach carver or pen knife. Materials: Basewax; blue casting wax (26-gauge); absorbent cotton. Procedure: (Follow operations in the order presented here.) CAUTIONS: a. D o not press too hard on wax as the arranged teeth may be displaced. b. To prevent burninx and distortion do not flame wax too lonx. c. ~ ~ wax p evenly ? ~i n d not too thickly on palate. . d. Teeth should not be covered with wax too far over the buccal and labial surfaces. e. W a x should not be too thin over t h e pins of the anterior teeth. f. D o not allow pits to remain in the wax. g. T r i m borders bf wax dentures to prevent cuttilzg or scra~ching the patient's mouth durilzg t r y i n . h. W i p e waxed denture with alcohol for hygienic reasons, before returning to dentist. I. Make wax bases on an upper and lower set of casts which have had reliefs and tinfoil applied. (Follow procedure in Unit No. 6 (11) ; Process or Principle No. I I ; Job. No. 28) There will be no teeth arranged on this set of casts. NOTE: These casts will be used later for technic purposes in the instruction UnitJ to follow. 2 . I n the full cases, after the teeth have been arranged, add melted wax to reenforce teeth, extending ridge-like elevations half way toward the rim of the denture on the buccal and labial surfaces, opposite each of the teeth. (Fig. 167.) 3. Adapt a piece of wax, folded to double thickness, over the buccal and labial surfaces, allowing the ridge-like elevations to remain on the buccal aspect, especially at the cuspids, less at laterals, gradually less about the molars and least at the lower incisors. (Fig. I 68.)

DENTURE WAXING TECHNIC

I77

Note: D o not make the elevations too pronounced. T h e elevation over the cuspid should be most prominent, that over the lateral incisor least prominent. T h e elevations should be smooth and should not extend too far toward the rim of the denture. In the lower denture the elevations below the anterior teeth should be practically eliminated.

.

'

Note: Fold a sheet of basewax to double thickness. Allow the wax to extend over the cervical thirds of the teeth and past the rim of the denture.

178

DENTURE WAXING TECHNIC

MANUAL FOR DENTAL TECHNICIANS

I79

4. Holding the penknife with a pen-grasp, festoon all teeth at the junction of tHe buccal, labial and lingual surfaces at the "collar" of the artificial teeth, and in the approximating spaces between the teeth. All festoons should be at right angles to the long axes of the teeth. (Figs. 169, 170 and

Note: Festooning should follow the cervical line a t the beginning of the "collar." T h e wax at the interproximate surfaces between the teeth should not be d u g out too deeply. In this illustration the wax has been trimmed around the rim of the denture to follow the denture limit. T h e rim should be smooth to avoid injuring the patient's mouth when the dentist tries the dentures in the mouth.

Note: Another method of carving buccal and labial surfaces of waxed denture is to wax denture completely and then use a Roach carver to form buccal and lingual elevations. T h e method shown in Figs. 167 and 168 is easier for the beginner. A-Plaster holding lower cast to articulator. B-Lower cast. C-Denture base. cast. F-Plaster holding upper cast to D-Upper denture base. &Upper articulator. G--Wax before carving.

5. 6.

7. 8. Note: T h e w a x should be festooned a t right angles to the long axes of the teeth. the anterior teeth having pins, the wax should cover the pins well.

111

171.) Do not festoon too deeply in the interproximate spaces between the teeth. Smooth the wax around the teeth and on the palatal surfaces. (Fig. 172.) Soften a piece of 26-gauge blue casting wax between the palms of the hands and adapt over the palatal surface. (Fig. 173.) Trim the blue casting wax on the palatal surface, seal with heated spatula and festoon around the teeth with a penknife. (Figs. 173, 174, .175 and 176.) Eliminate all pits and other imperfections in the wax, using wax spatula, or pick up the Bunsen burner and pass the flame quickly over the area to be smoothed.

I 80

MANUAL FOR DENTAL

TECHNICIANS

181

DENTURE WAXING T E C H N I C

9. Using cotton wad, polish the waxed denture after chilling and while holding under running cold water (Figs. T 76, 177)10.I n waxing partials follow the gingival contours around the remaining teeth on the cast as in making partial denture bases (Unit No. 6, 11) and in making partial biteplates (Unit No. 7) (Fig. 178).

FIG.1 7 3 . FESTOONING O N T H E PALATE AROUND

Note: The wax has been festooned around the lingual surfaces of the teeth. I I.

Keep wax away from the labial and buccal surfaces of teeth set (butted) against the gum in partial cases. Allow only a small amount, if any, wax to show in the interproximate spaces of teeth set against the gum.

Supplementary Assignment: (Information to be obtained by the learner.) I. Various waxes used. 2 . Different methods of carving wax on labial and buccal surfaces.

THE

TEETH

3. Different types of wax obtainable for waxing. 4. Rugae; application of artificial rugae. 5. Other methods of festooning wax. 6. Other methods of polishing wax. Questions : I. What happens if too much pressure is applied on wax? 2. Why should all pits and irregularities in wax be eliminated? 3. Why is wax added on the palatal surfaces of the baseplate dentures? 4. Why should wax completely cover pins on teeth? 5. Why is it necessary to have a uniform thickness on palate? 6. Why should waxing not be too thick on lower dentures? 7. Why should waxing not be too thick on upper dentures? Job Appraisal : I. Have all pits and other imperfections been eliminated? 2 . Has the wax been properly festooned around the teeth?

I 82

DENTURE WAXING TECHNIC

MANUAL FOR DENTAL TECHNICIANS

A-Carved

183

rugae.

(LINGUALSURFACECARVED) FIG. 175. LOWERDENTURE A-Carving

to extend lower tooth forms.

Note: Carving on lingual and palatal surface to extend the outlines of the teeth is of advantage, especially where the natural alveolar ridges of the patient have receded, because it allows more room for the tongue.

Note: T h e outline around the teeth of the cast is sharp and the buccal extensions of the denture are well finished. Where the teeth are butted against the cast, they do not show any wax a t their interproximate spaces on the labial surface.

3. Are the pins on the teeth covered and not visible on the palatal surface?

4. Are the teeth sealed tightly to the wax? 5. Is the wax carved and polished? 6. Can you wax a case in 25 minutes (average)? REFERENCES: (Books for Additional Information.) I. Nichols,

I. G.: Prosthetic Dentistry. St. Louis: C. V. Mosby Company,

193'. Frahm, F. W.: Principles and Technics of Full Denture Construction. Brooklyn: Dental Items of Interest Publishing Company, 1934. 3. T u r n e r , C. R. and Anthony, L. P.: American Textbook of Prosthetic Dentistry. Philadelphia: Lea and Febiger, 1932. 4. Swenson, M. G.: Outline of Full Denture Prosthesis. N e w York: N e w York University Press, 1932. 2.

Side View

Front View

Note: T h e wax is free of pits, it is polished, and the carving is not too pran?uncecl or too high toward the rim of the denture. T h e carving at the lower anterlorr 18 not prominent. T h e wax has not been d u g out too much between the teeth. While the teeth are well exposed the wax nevertheless covers the collars of the teeth.

I 86

DENTURE FLASKING TECHNIC

MANUAL FOR DENTAL TECHNICIANS

187

Vocational Information: Flasks consist as a rule of three parts: ( I ) a lower (base) or shallow part which has a floor or base, ( 2 ) an upper (counter) or deeper part which fits over the lower and (3) a cover. (Fig. 179.) Flasks may be closed firmly by the use of bolts and nuts or by using flask clamps. Flasks are made of iron, brass or bronze. Bronze flasks are most desirable because they are

FIG.180. DENTURE FLASK Note: This type of denture flask is used in conjunction with a flask clamp.

not affected by sulphur, can be easily cleaned and are not distorted

i n use. I.

2.

Clamp flask. a-Cover. b-Upper part (counter). c-Lower part (base). Bolt flask. a-Cover. b-Upper part (counter). *Lower part (base). 3. Bolts and nuts for bolt flask.

Tools and Equipment: Vulcanite denture investment flask; flask press; flask clamp; plaster bowl; plaster spatula and plaster knife. (Figs. 180, I 81.)

188

DENTURE FLASKING TECHNIC

MANUAL FOR DENTAL TECHNICIANS

189

Materials : Plaster, water, shellac, Sandarac and liquid soap. Procedure : (Follow operations in the order presented here.) CAUTIONS : a. Examine the waxed case (waxed denture and cast) carefully b. c. d. e. f. g. h. i. j.

k.

before immersing it i n water t o make sure that t h e denture is properly sealed to the cast. Examine the teeth to make sure that they are securely waxed. B e careful not to loosen t h e teeth when using wax solvent to remove excess wax. T o prevent breaking the cast during vulcanizing, do not trim too thin. Be sure that the cast clears the sides of the flask to prevent breakage of the cast. Minimize undercuts by setting t h e long axes of t h e teeth at right angles to the base of the flask. M a k e sure that the teeth are not in direct contact with the sides of the flask or too close to the cover of the flask. Keep t h e teeth free from separating media or lubricants. D o not cover the top r i m of the flask itself or the upper part of t h e flask will not fit properly. T o avoid loosening the teeth or displacing t h e base, do not jar the flask too hard when pouring plaster into the "counter." D o not cut plaster teeth lower than the wax base or too close to the gingival margin in flasking partial cases. Be sure that plaster in counter is poured well into the spaces between the teeth.

Carefully seal all around the rim of the waxed denture so that it is fast to the cast; with the plaster knife remove the cast with the sealed waxed denture from the articulator extension arm. 2. Using the plaster knife, trim the cast so that it clears the sides of the lower half of the flask. Set the cast in the lower part of the flask. (Figs. 182 and 183.) 3. Place the upper or counter part of the flask in position over the lower, place the flask cover in position. Make sure that the teeth do not touch the sides or the cover of the flask. (Fig. 184.) 4. Remove the cast from the flask and immerse the cast in cold water until nll bubhling ceases.

A-Lower

part (base) of flask. C-Lower

B-Cast, clearing sides of lower part of flask. denture sealed to cast.

FIG.183. UPPERWAXEDDENTUREI N LOWERHALF (BASE)OF FLASK A-Lower

half of flask. B-Upper

denture sealed to cast.

Note: T h e importance of making sure that the teeth are clean and firmly attached to the wax and that the denture base is sealed all around the cast-bucally, lingually, palatally in upper and linqually in lower-cannot be overemphasized.

I.

A-Lower part (base) of flask. B-Upper part (counter) of flask. &The sealed wnxed denture. This is immersed in water so that the plaster used in flasking will not lose its strength through having water absorbed by the dry cast.

Note: 111hiis ill\~str;~tion we call see that the teeth do not touch the sides of the flask IIIIII 11i:tt we II:IVC:~lnpleroom hctween the edge of the teeth and the top of the flask.

IgO

MANUAL FOR DENTAL TECHNICIANS

DENTURE FLASKING TECHNIC

I9I

5. Make a plaster mix and fill the lower half of the flask to about two-thirds of its capacity. 6. Set the cast into the plaster in the lower half of the flask, so that the occlusal plane of the teeth is parallel with the bottom or base of the flask. (This can usually be accomplished by setting the heels or condyles of the cast somewhat lower than the anterior portion (Figs. 185, 186 and 187).

A-Denture waxed and sealed to cast. B-Plaster has been smoothed and removed from waxed surface a s well as from top rim of sides of flask. C-Lower half of flask. A-Denture

waxed and sealed to cast. B-Plaster into which cast has been invested. C-Lower portion of flask.

Note: T h e long axes of the teeth are parallel with the vertical elevation (sides) of the flasks. T h e plaster is smooth and there are no undercuts between the plaster and the waxed denture. If directions are not followed properly all the preceding work will be in vain.

Note: T h e case is centered in lower half of flask. T h e plaster comes up to side of cast, below waxed denture base.

7. Mould the plaster, removing all excess, between the rim of the denture and the rim of the lower half of the flask. Wait until plaster sets. (Figs. I 88 and I 89;) 8. Apply shellac and sandarac or liquid soap to the plaster between the periphery of the waxed denture and the rim of the flask. (Figs. r go and 191.) NOTE: Wait until separating medium is dry before proceeding. T h e preferred method is to apply tinfoil over the casts as explained in the following Unit (No. 13). T h e counter or upper part of the flask should be poured after the tinfoil is applied. Tinfoil is extended to cover this portion of the plaster between the cast and the flask and also the wax and part of the teeth. (See Unit No. 13.)

A-Lower

half (base) of flask. B-Plaster into which cast has been set. C-Waxed denture sealed to cast.

Note: I n these illustrations we note that the dentures are centered in the lower half

of the flask. T h e plane of the teeth is parallel with the floor of the flask. T h e plaster does not cover the rim of the flask or the wax the dentures.

192

MANUAL FOR DENTAL TECHNICIANS

9. When the separating medium is dry or after tinfoil is applied, as shown in Unit 13, and the denture is sealed to the cast, set

10. I I.

the upper or counter part of the flask in position over the lower. Make a plaster mix and fill the upper or counter portion of the flask, pour the plaster along the side of the flask to prevent the inclusion of air bubbles. Jar the flask to make sure air bubbles are excluded. Place the cover in position and wipe all excess plaster from

DENTURE FLASKING TECHNIC

I93

Supplementary Assignment: (Information to be obtained by the learner.) I. Various types of flasks, advantages and disadvantages of each. 2. Separating media, types commonly used in commercial laboratories; advantages and disadvantages of each.

FLASKBD I N BOLTTYPE FLASK FIG. 190. UPPEIZDEN.TURE A-Lower

half of flask. B-Plaster into which cast was set for flasking. &Waxed denture sealed to cast.

Note: A careful examination reveals that the flask is clean, the plaster is smooth and well adapted to the cast but does not cover the waxed denture. T h e long axes of the teeth are parallel with the vertical elevation (sides) of the flask. There are no undercuts between the waxed denture and the plaster. W e can also see the details in the waxing. T w o different shades of wax were used in this case; one, a light color for the buccal and lingual surfaces, and the second, a dark color for the palatal surface and over the condyles.

the outside and rim of the flask. (Figs. 192 and 193.) If bolt type flask is used place bolts in position and tighten nuts. 13. I n partial cases, cut the remaining (plaster or stone) teeth on the cast to within 1/16 inch of the wax base. (Figs. 194 and 195.) 14. I n flasking the wax denture bases follow the general instructions for flasking full dentures. Use separating media or preferably liquid soap and pour the counter or upper part of the flask. (Fig. 185.) 12.

,

A-Lower half of flask. Note: All plaster has been removed from the outside of the flask and from the rim so that the upper part of the flask will fit accurately. B-The plaster used for flasking has been smoothed and molded around the cast and covered with liquid soap. C-The cast. Note: T h e cast is centered in the lower half of the flask. I t does not touch the sides of the flask and there is a layer of plaster between it and the base of the flask. D-The relief metal over the hard area and over the rugae. E-The baseplate of the denture base covered by a sheet of 26-gauge blue casting wax. Note: T h e baseplate has been cut in half to show the details of the relief over the hard bony areas on the cast. T h e denture base is sealed to the cast so that there are no undercuts between the cast and the denture base. F-The basewax into which the teeth have been set. Note: T h e wax has been festooned properly around the palatal surfaces of the teeth. T h e pins of the anterior teeth have been covered. G-The teeth. Note: T h e teeth are clean. All wax has been removed from them. If the teeth have wax on them they will become loose when the wax is eliminated or during the process of packing dental rubber. T h e long axes of the teeth are parallel with the side of the flask. T h e plane of the teeth at the incisal edges and occlusal surfaces is parallel with the floor of the flask.

3. Methods of removing excess wax from teeth. 4. Methods of avoidinn extreme undercuts in flasking cases. Various methods of cutting off plaster teeth in cases.

5.

= 94

MANUAL FOR DENTAL TECHNICIANS

DENTURE FLASKING TECHNIC

I95

Note: T h e plaster teeth should be cut at a slant outward to the edge of the cast or crescent shaped in a mesio-distal direction. Never cut the teeth flush with the wax. Always allow the plaster teeth to extend higher than the wax.

A-Plaster used for flasking case. B-Upper cast. =Waxed denture (denture matrix). D-Diatoric tooth. %Upper half of flask. F-Cover of flask. GLower half of flask.

A-Plaster used for flasking case. B-Lower cast. C-Waxed denture (denture matrix). D-Diatoric tooth. E-Upper half of flask. F-Cover of flask. GLower half of flask.

Questions: I. Why are dentures flasked? 2. What precautions should be observed when flasking in the lower or base portion of the flask? 3. What precautions should be observed in pouring the counter portion of the flask 4. Why must the waxed dentures be sealed to the casts? 5. Why is it necessary to remove excess wax from tooth surf aces? 6. Why should the teeth be waxed securely? 7. How may undercuts be avoided?

A-Flask. B-Plaster used in flasking. C-"Horseshoe" shaped denture. D-The plaster teeth have been cut to about two millimeters higher than the wax of the trial denture base. Note: T h e cast is centered in the lower half of the flask and parallel with the base of the flask. T h e waxed denture is sealed securely to the cast around the edge of the denture.

8. I Y h ! arc sepal-atiiig medin used atid wh!. should scl>nratiug tncdi;~I)c kel)t ;IM.;L! (I-0111t lic tcct li l' 0 . l h u . C:III the teeth 1)e i ~ i j ~ ~ ;I ~ -i cl l ddil-ec,t co11tac.t with the sides or top of the flask? lo. il'hy should plaster teeth in partials Ile cut higher than the wax? I r . W h y is licluid soap or tin foiling better than separating ~ n e d i a in flaskingi

Job Appraisal : W a s the cast trini~ncd to fit wcll i l l the lower part of the flask.? 2 . Are the tceth out of colitact with the uppel- part alid with the cover of the flask? 3 Lloes the p l ; ~ s t e used ~ - in flaskilig clear the edge of the waxed denture? 4. il'erc ~lndct-cutsa~roidedto facilitate separatilig the flask.; 5. Can 1 0 ~ 1flask :1 case iri 1 0minutes (averagc ) ;. I.

I~-e;~kable hut call bc repaired by : ~ , l t l i n ,FI-csh ~ clcnt:~l ~-ul>berslid I-cvulca~lizing. T h e revulcanized , l c . ~ ~ t ; I~ IlI I , I I ~ I - is thcri trimmed 2nd polished. Although the repaired I ~ ( . I I I \isI I: -I~~. : S~~ I~~ V I~ CIC ' : L I > I Cthc , new L ' u I c ~ I ~ ~ :ip~>cars ~c lighter t h x r l ."5

286

MANUAL FOR DENTAL

DENTURE REPAIR TECHNIC

TECHNICIANS

the original vulcanite of the denture which becomes darker. Den tures may be repaired several times as occasion demands. However, it is better to replace all of the old vulcanite if extensive or repeated repairs become necessary. Vocational Information: The parts of the broken denture are assembled into their original relationship, a matrix (cast) is made under the denture and the edges of the parts are prepared for receiving additional vulcanite. The denture may then be "cold packed" or "wet packed" and revulcanized. Special rubbers or the regular dental rubbers may be used for repairing vulcanite dentures. Tools and Equipment: Plaster bowl, plaster spatula, plaster knife, glass slab, wire nails, articulator, flask, wax, spatula, penknife, vulcanizer and attachments, all trimming and polishing tools. NOTE: (Tools and equipment used in waxing, flasking, boiling out wax, packing, cleansing, trimming and polishing are used in denture repairing.) Materials: Sticky wax, petrolatum jelly, basewax, plaster, water, dental rubber, sandpaper, pumice, chalk. NOTE: (Materials used in waxing, flasking, boiling out wax, packing, cleansing, trimming and polishing are used in denture repairing.) Procedure: (Follow operations in the order presented here.) CAUTIONS: a. T h e fracture-edges must be accurately approximated to prevent distortion oj the denture. b. Avoid applying sticky wax on the tissue surface of t h e denture. c. Be sure to lubricate the tissue surface of the denture before pouring the stone or plaster cast. d. A strip of vulcanite of about g" must be filed or ground away between the fracture-edges after making the matrix ( a stone or plaster cast or foundation on which the fractured denture is repaired and revulcanized). e. All of the polish should be removed from the denture for a distance of g" beyond the edges to be repaired. f. Dove-tails should be between %" and g" i n size and no/ over g" apart. g. W h e r e dovetails are not used, the vulcani~eskould he rlS of its original thicknrs.~N / /hr e/l.ec.s l o hn join/,,/, duced to n ~ tken d m7h.chened wit11a h f ~ r .

287

h. Only the waxed surfaces s h o d d be expo~edin investing the dmtzcre to be repaired in fEasKs. i. Handle the denture carefully while trimming and polishing. j. Be careful to keep the artificial teeth in the exact positions hdicated by the index ( a plaster wall used to peserve the

A-Loose

tooth. B and C-Broken of lower denture.

parts

A-Clasp in place after the vulcanite has been ground out to receive the clasp extension. B-Plaster matrix.

A and B-Parts

of upper denture.

A-Dovetails. B-Loose tooth in position. C-Vulcanite thinned and honeycombed with a bur.

Note' Either dovetailing or the thinning and roughening method may be used. T h e cast poured to hold the denture is known as the "matrix."

288

MANUAL FOR DENTAL

TECHNICIANS

DENTURE REPAIR TECHNIC

289

relationship of the teeth to the denture base) when replacing vzllcanite dentare bases. k. I n remakes, avoid changing the original relationship of the teeth to the denture base (keep the articzllator set-screw seczlrely locked). 1. Cover the teeth v i t h a layer of basewax before passing the dentzlre through the flame to soften the vulcanite so that the teeth can be removed without fracturing. NOTE: (Observe all cautions indicated for waxing, flasking, boiling out wax, packing, cleansing, trimming, and polishing.)

I. Simple denture repair: I. Approximate fractured edges and seal the broken parts with sticky wax and wire splints, laid at right angles over the line of fracture. (Figs. 265 and 266.) 2. Lubricate tissue surface with petrolatum. 3. Apply a basewax or carding wax strip around the periphery of the denture as in boxing impressions. 4. Mix plaster and pour a matrix (cast) of the denture as in pouring impressions. (Figs. 267 and 268.) 5. When the plaster of the matrix has set, remove and cleanse the fractured denture parts. 6. Using vulcanite burs, separating discs and abrasive files and wheels, as found necessary, dovetail and remove polish for a distance of S'' parallel with the fracture-edges. (Figs. 269, 270 and 271.) 7. Replace fractured parts on the cast, fill in missing parts of vulcanite with basewax, waxing somewhat thicker than thc original vulcanite denture itself. 8. Trim the plaster matrix (cast) and invest in flask, covering all surfaces except waxed areas. (Fig. 272.) 9. Proceed with flasking, packing, vulcanizing, finishing and polishing as described in the respective units. (Fig. 273.) 11. Denture repair involving loosened teeth: A. When the same artificial tooth can be replaced. NOTE: Where the denture base indicates the exact position of the loose tooth, cut a dovetail in the lingual or palatal surface of thc vulcanite adjacent to the tooth, replace the tooth in its original posi tion, wax it securely with sticky wax and proceed as in simple repairs. B. Where the loose tooth is broken and a new tooth is to bc used but the denture base at the site of the tooth is intact.

A-Matrix (cast). B-Assembled bro- A-Wax rim around broken denture. ken denture showing wire reenforcement. M i r e reenforcement.

Note: T h e wax rim reenforces the denture so that the parts are not disturbed when the matrix is poured. T h e wax rim helps to obtain a more evenly rounded matrix.

A-Prepared edges of fracture, honeycombed with bur. B-Trough on matrix around denture after removing the wax rim placed around the denture before the matrix was poured. N o t e : Dental rubber may be heated on the packing table and worked into the space to be repaired by using a clean hot spatula.

\

DENTURE REPAIR TECHNIC

290

291

MANUAL FOR DENTAL TECHNICIANS

NOTE: T h e dentist supplies the technician with a wax "bite" indicating the relationship of the teeth of the opposing jaw, and a new artificial tooth, or the make, shade and mould number of the tooth to be used. I. Proceed as in simple repairs until the matrix is poured. 2. Mount the wax "bite" on the denture, fitting the teeth of the denture into their tooth depressions on the "bite" as indicated, and seal the wax "bite" securely to the teeth of the denture. (Fig. 274.)

Note: T h e denture is covered with plaster excepting over the area to be packet1 with dental rubber.

A-Denture.

B-Teeth

on denture.

&Bite

mounted over denture and matrix.

Note: The plaster mix for pouring the "bite" should be looser than for other purposes.

B e sure plastei fills the tooth depressions before building up the plaster on the "bite."

3. Fill with plaster the tooth depressions left in the "bite" by FIG. 273. REPAIRED UPPERDENTURE Note: T h e lines of division between the old and new vulcanite can be seen the palate.

on

the teeth of the opposing jaw. 4. Mount the matrix with the denture and poured "bite" on an articulator. 5. Remove the "bite" from the denture and the poured "counter" or cast of the opposing. teeth. (Fig. 275.) 6. ,Place the new tooth in position as indicated by the bite and

292

MANUAL -FOR DENTAL TECHNICIANS

DENTURE REPAIR T E C H N I C

Lubricate the tissue surface of the denture and impression or apply separating media to the impression part (if the impression part consists of plaster.) 2. Apply a wax rim around the periphery of the denture and impression. 3. Pour the matrix (cast). 4. Apply the wax "bite" to the denture and wax it securely. (Fig. 274.) 5. Pour the "bite." 6. Mount the matrix with the denture and "bite" on an articulator. 7. Remove the "bite" and add teeth as in adding new teeth to broken denture and proceed as in simple repairs. (Fig. 275.) 111. Repair of partial denture with loose clasp. NOTE: (The dentist takes an impression of the clasped tooth with the clasp and denture in position.) I. Pour the impression and denture as directed for adding teeth to a partial denture. 2. Cut out the vulcanite of the denture base around the extension (tail-piece) of the clasp. 3. Proceed with waxing,' flasking, packing, etc., as in simple repairs. IV. Replace entire vulcanite on palate of a n upper denture. (Fig. 276.) I. Assemble the broken denture parts and pour a matrix as in simple repairs. 2. Using separating disks on a mandrel mounted on the bur chuck of the lathe, cut away the entire palatal vulcanite flush with the palatal (lingual) surfaces of the teeth. (Fig. 276.) 3. Using round burs, roughen the vulcanite under the teeth by honeycombing it with the bur. 4. Wax the denture and proceed as in simple repairs. V. Replace entire buccal and labial (gum) vulcanite of a n upper o r lower denture. I . Assemble the broken denture parts and pour a matrix as in simple repairs. 2. Using an abrasive wheel reduce the gum vulcanite to about one-half of its original thickness. 3.. Using a vulcanite bur, honeycomb the remaining gum rubber with the bur to roughen it. (Fig. 277.) I.

Note: T h e bite has been removed. T h e denture, the matrix and the counter of opposing teeth are shown mounted on an articulator.

tllc

the arrangement of the adjacent teeth of the denture to 1)c. repaired. NOTE: [It is often necessary to grind the incisal or cervical edgcs of the new tooth to be added, in order to fit it into position. l'hc gum rubber at the neck (the collar) of the tooth should not I)c ground away. T h e denture, especially when an anterior tooth i s being replaced, will look better if the original gum rubber is prc served.] 7. After the tooth or teeth are arranged in proper position, ~ M - I I ceed as in simple repairs. C. Where additional teeth are to be added to partial denturc.~. NOTE: (The dentist takes an impression and wax "bitc" 01' the part where new teeth are to be added and supplics thc tc.c,l~ nician with the teeth or specifies the make, shade, and moult1 ( 1 1 the teeth to be used.)

293

294

MANUAL FOR DENTAL TECHNICIANS

4. Carefully cut away the gum rubber around the necks of the teeth. 5. Wax the buccal and labial surfaces. 6. Flask the denture by filling the lower part of the flask with plaster of a fairly stiff mix and set the denture with the teeth down, while on the matrix, into the newly mixed plaster,

DENTURE REPAIR TECHNIC

I

295

ing the plaster of the index about j/4" away from the indsal and occlusal surfaces of the teeth. (Figs. 280 and 28 I .) 4. Cut a dent on the index opposite each of the cuspid teeth of the denture, to weaken the plaster, and remove the index from the denture and cast. 5. Remove the denture from the cast and remove the teeth from the denture by first covering the teeth with a layer of melted basewax and passing the denture quickly several times through the flame of the Bunsen burner to soften the vulcanite. 6. Arrange the teeth in position as indicated on the plaster index and secure them with sticky wax.

METHODO F REPAIRING FIG. 2 7 7 . METHODO F PREPARING UPPER DENTUREFOR NEWPALATE RUBBER OF LABIALSURFACEOF DENTUREFOR APPLICATION OF NEW RUBBER

FIG. 276.

A-The vulcanite under the teeth has been honeycombed with a vulcanite bur. T h e pins on the anterior teeth have been exposed.

A-Plaster matrix. B-Gum rubber thinned out and honeycombed for new applied to desired rubber. C-Wax thickness.

Note: Plastic rubber or heated dental rubber may be applied directly without waxing.

being careful to have the teeth at least g''from the bottom of the flask. (Fig. 278.) 7. Smooth the plaster around the teeth and over the cast at the rear of the denture, making sure that all of the waxed part has been exposed. Lubricate the plaster. 8. Pour the upper part of the flask and continue as in simple repairs. (Fig. 279.) VI. Replace the entire vulcanite denture base. NOTE:(Proceed as in simple repairs until the matrix is poured.) A. When the matrix is not to be mounted on an articulator. I. Make a groove on each and in front of the matrix at right angles to the base of the matrix and the denture. 2 . Lubricate the teeth and the buccal and labial surfaces of thc denture and matrix. 3. Build a plaster index around the denture and matrix, extend-

A-Plaster matrix. T h e denture is flasked with teeth toward the base of the flask. B-Wax to be boiled out after the upper part of the flask is poured.

7. Construct a baseplate over the cast (the matrix) and arrange the index containing the teeth around the matrix with the baseplate. 8. Flow basewax into the separations between the teeth and the baseplate. (Fig. 284.) 9. Remove the sticky wax holding the teeth to the index and remove the index. 10. Finish the waxing where necessary without disturbing the position of the teeth. I I.. Proceed as in flasking a newly waxed trial denture.

1

296

DENTURE REPAIR TECHNIC

MANUAL FOR DENTAL TECHNICIANS

297

NOTE: (Basewax may have to be used instead of the baseplate to avoid disarranging the teeth in the index.) B. Where an articulator is to be used: I. Proceed as in simple repairs until the matrix is poured, then lubricate the teeth on the denture. 2. Deposit a stiff plaster mix on a glass slab and press the teeth of the denture on the matrix into the plaster mix which now , becomes the tooth index.

FIG. 279. FLASKOPENED FOR BOILING OUT I-Counter.

2-Denture

flasked in lower part of flask.

A-Lateral part of index. B-Anterior part of index. C-The matrix, showing the trough left by the wax rim. D-The denture base to be replaced. E--Part of index, showing method of extending above the occlusal surfaces of the teeth.

Note: T h e trough on the matrix around the denture made by the wax rim and a vertical cut on the matrix help to replace the index in the same position. T h e index is higher than and extends over the incisal edges of the teeth.

A-Reenforcements

on fractured denture.

B-Index.

C-Matrix.

Note: T h e matrix and denture should be lubricated in order to make the separ:~ti~)~l of the index from the matrix and denture easier. T h e plaster wall around I I I ~ . denture and matrix is known as the "index."

3. Trim the tooth index and mount the denture on the matrix and the tooth index on an articulator, securing the set-screw to hold the relationship of the index to the matrix when the denture is removed. (Fig. 282.) 4. Cover the teeth of the denture with a layer of basewax, pass through the Bunsen flame until the vulcanite is soft, remove the teeth from the denture, arrange on the tooth index and .fasten them with sticky wax. (Fig. 283.)

29 8

MANUAL FOR DENTAL TECHNICIANS

DENTURE REPAIR TECHNIC

299

5. Make a baseplate or basewax denture base over the cast. 6. Adapt a wax roll over the denture base and wax the teeth to it securely. (Fig. 285.) 7. Remove the sticky wax holding the teeth to the index and complete the waxing. (Fig. 286.) 8. Proceed with flasking, boiling out wax, packing, etc., as with wax trial dentures, until completion. Supplementary Assignment: (Information to be obtained by the learner.) I. Various methods followed in repairing dentures. 2. Various methods of adding new or additional teeth. 3. "Jumping the bite."

X-Tooth

depressions on index.

T h e index poured for teeth and the denture on the matrix are articulatetl. All of the denture base is to be replaced without disturbing the relationship of tllc teeth to the cast. T h e set-screw of the articulator must be properly adjusted.

Note:

FIG. 283. TEETH ARRANGED IN THE INDEX A-Matrix. B-Teeth. &Index. Note: T h e matrix of the original denture is now ready to receive a denture base. T h e teeth are then waxed to the denture base and separated from the index.

4. "Rebasing." 5. Different rubber preparations for cold packing. 6. Various methods of flasking. 7. Methods of removing teeth from vulcanite dentures. 8. Methods of grinding teeth. 9. Method of reenforcing assembled parts.

DENTURE R E P A I R T E C H N I C

MANUAL FOR DENTAL TECHNICIANS

300

WAXEDIN INDEX FIG.284. DENTURE WAXEDI N INDEX FIG.285. DENTURE WITHOUT

A-Index.

ARTICULATOR

B-Waxed Matrix.

denture.

WITH

C-

ARTICULATOR

A-Matrix. B-Basewax with teeth waxed to base. C-Index. D-Teeth held in index with aid of sticky wax but not yet joined to base.

Note: When the case is articulated be sure the set-screw is tight. T h e teeth shoultl be arranged in their proper positions in the index before waxing them to the w a x denture base.

30'

Questions : I. Why must the broken parts of the denture be accurately assembled? 2 . Why should the assembled parts be reenforced? 3. Why are the teeth secured to the index? 4. Why is it necessary to secure the set-screw firmly when an articulator is used? 5. What are the advantages and disadvantages of cold packing? 6. What precautions should be taken in removing teeth from dentures? 7. How should the teeth be secured to the denture base in "jumping the bite." 8. What is the purpose of dovetailing? 9. Why should the polish be removed from the denture near the edges to be repaired?. 10.What is the purpose of roughing the vulcanite with burs? 11. What methods other than dovetailing may be employed to secure old vulcanite to new rubber? 12. What effect does revulcanization have on vulcanite dentures? Job Appraisal : I. Were the parts accurately assembled? 2. Were dovetails and grooves cut according to the directions? 3. Were the teeth accurately replaced in the index? 4. Were the teeth removed from the denture without breaking them? 5. Was the denture properly vulcanized, trimmed and polished? REFERENCES: (Book for Additional Information.) > .

C. R. and Anthony, L. P.: American Textbook of Prosthetic Dentistry. Philadelphia: Lea & Febiger Co., I 932. 2. Nichols, 1. G.: Prosthetic Dentistry. St.. Louis: C. V. Mosby Co., I 930. 3. Frahm, F. W.: T h e Principles and Practice of Full Denture Construction. Brooklyn: Dental Items of Interest Publishing Co., 1934. 4. Skinner, E. W.: T h e Science of Dental Materials. Philadelphia: W . B. Saunders Co., I 936. I. T u r n e r ,

Note: The denture is an exact duplicnte of the origillnl as f a r :IS IIN. ti1 :111tl 1111. relationship of the teeth to thc matrix are concc.~.~~c.tl.

KEI,ATEI> I N I ~ O K M A T I O N : U N I T NO.

20

D E N T U R E REPAIR TECHNIC Plastic rubber: Compounds of plastic rubber are sometimes used in repairing vulcanite dentures. T h e plastic rubber is used instead of wax. After flasking the cast: is placed in the vulcanizer without the necessity of boiling out or packing. Removal of teeth from vulcanite denture: Place the denture into a tin box containing sand. Heat the box until the sand is red hot. Allow the sand to cool, remove the denture and the teeth will be found loose and easy to remove. Properties of repaired vulcanite: T h e repaired denture is not strong as it was originally. Revulcanization causes a slight shrinkagr of the vulcanite. Dry-Packing: Instead of waxing the part to be repaired, dental rubber may be heated on the packing table and inserted with a hot wax spatula into the part to be repaired. Care should be taker! to pack the rubber tightly. T h e spatula must be kept absolutely c l e a ~ ~ to prevent foreign particles from becoming incorporated with thy rubber.

1

r

I n. .a . u r. n . .

ux.

3 0 ~

n07

APPENDIX I1

APPENDIX I1

( C ) Related Information (a) Vocalional Informalion

ANALYSIS O F U N I T NO.

I:

I.

( A ) Processes and Jobs No.

I.

a. b. c. d. e.

(a) . . Process or Princiblc Dental waxine: Handling and-cutting basewax Melting and sealing basewax Manipulation of carding wax Use of wax spatula Use of Bunsen burner

4. Modified plasters 5 . Method of storing plaster plaster tools and equipment

&. Care of

( b ) Project or Jobs No.

I:

a. Construct a sealed wax box 4 5 x 4 5 I I I ~ L I . b. Construct a wax art-base form t o g i v r ~ t dimensions

,lNALYSIS O F U N I T NO. 3: I'KEPARATION O F P I A S T E R 1MPRI':SSIONS F O R CrlSTS--1 (.4)

( B ) Laboratory Instruclion (0) Tools. Equipmen1 and Malerials I . Laboratory hench 2 . Bunsen hurner with gas tu1,~ng 3 . Wax spatula 4. hllllimeter ruler 5. Penknife 0. Pink basewax 7. Carding wax 8. Absorbent cotton

(b) Operations Using mm. ruler Handling andcuttingwax Using wax spatula Melting and sealing basewax Handlinrr. cuttinp and sealinn cardrne wax -

I. 2.

3. 4.

s.

(6) Laboratory Pracliceh Cutting waxes and using u., spatula 3 . Polishina basewax 4. Sealing 6asewax I.

z . Heating

(a) Process or Principle So. 3. Assembling impressions: a. Application of sticky wax b. Handling broken parts of plasterimpresslnns c. Arranging broken parts in dental im~ ~ r e s s i otrays n (1. Assembling impressions without using trays

(b) Projecl or Jobs No. 3 . Assemble four sets of full (edentulous) upper and lower impressions in trays No. 4. Assemble four sets of full (edent~llons) upper and lower impressions without using trays No. 5. Assemble six partial (partially edentulous) impressions in trays KO. 6. Assemble six partial (partly cdentulo~is) in~pressionswithout using trays

( R ) Laboratory Instruction

( C ) Related Information

ANALYSIS O F U N I T NO.

(b) Subblenrenlarr .. - Assianmenl~ I . Ingredients of wares 2. Degrees of heat attained by Bur~st:rtl , i ~ t flame j . Analysis of Bunsen burncr flamc 4. Physical changcs in heating and chilii~ir:n s. Gauaes (thicknesses) of different w : i h s usesof each

I. 2.

4.t

2:

PI,ASrl'EK

1

3.

4. 5.

.C

6. 7. 8.

(a) Tools, Eguipmenl and Materials Camel's hair brush Wax spatula Bunsen burner Paper towel Tweezers Sticky wax Basewax Upper a n d lower full and partial impressions

TECHNIC

( A ) Processes and Jobs (a) Process or Prindfile Plaster work: a. Handling, mixing, shaping and trinlming mixed plaster b. Use of plaster spatula, knife. bowl and saw c. Use of sandpaper. chan~oiscloth anrl chalk in polishing plaster 2.

Processes and Jobs

-

-

(a) Vocalionol Informalion I. Kinds of waxes and uses 2 . Types of wax spatulas 3 . Types of Bunsen burners

Nu.

(b). Subblementar~ Assiannrenls -Origin and development of plaster for dental use 2 . Physical and chemical properties of plaster 3 . Con~positionof various plaster eompounds 4. Duties of plaster technician

WAX TECHNIC

No.

2.

(b) Projccl or Jobs Construct upper and lower a r t - i , : ~< .-. , I be used as wax trays

I.

(b) Operalions Arrangipg broken parts of impressions

2.

Brushing parts

of

debris from

3. Use of tweezers for hand-

ling plaster parts 4. Arranging plaster parts of impressions in trays 5. Fitting parts of plaster impressions 6. Application of sticky wax 7. Fitting of parts without trays 8. Reenforcing with sticky wax

(c) Laboralory Praclices Using sticky wax Opening packages containing plaater impressions 3. Arranging parts in relative positions 4. Handling parts of plaster impressions 5. Cleansing of dental impression trays I. 2.

( C ) Related Information r. 2.

3.

4.

5.

(a) . . Vocalional Informalion Different types of impressions Types of sticky wax used Types of dental impression trays Use pf reenforcements in assembling im. presslons Types of tweezers used for holding plaster parts

(b) . . Subblemenlarv .- Assiannrenls Various imnrcssion materials Care of deGtal impressions Ingredients of sticky wax Precautions in assembling What to do when parts are missing

( B ) I , ( ~ b o r ~ ~ / 1o ~i,\trii(./~oi~ ry (a) l'ools, Equipmen1 onrl Malerials ( b ) Upcrol~otr\ ( i p ~ ~ l~: I~;tL i tS~LgV : I I . 1'I:~strrwo! k 2. Glass slab 2. Usir~gpIa\tcr l ~ t l i l t > I: I ~ , I V . I < . I 5. Plaster bowl 5. 'l'rirni!~\tii:1,1.#..lt,r 5 . I ' ( ~ I . , / I 1I ~~1 .I~ )~ :. I r - I 0 . Chamois clotlj 0. S:tnd[~:t(~c MII,: I>I., . I * ! 7. Mi~rkingrwnril 7. l',nli\l~if~j* 1t1.t .f ~,, I. , , I I ~ 9. Dcnt.iI j > l ; v , t < , ~ to. W:1t rr 1 1 . S : L ~ ~ I N~w~ , . ,(I L,tr(sl I ~I ~ ~ ~ 1 a. 'r,,I,

ANAT;YSIS O F U N I T NO. 3 : P R E P A R A T I O N O F DENTAIL IMPRESSIONS-I1 ( A ) Processes and Jobs Process or Principle .I Il*,\incdental impressions a. Clsc of c : ~ r < i i n ~ , w a x h. I':8h~s ~~c: .I. L',.,, 07 , re1:11111. (\l.(. 11111~.1'1..\11'S,\ < . I ' l < l l \ 1 0 1 : S ( . ; t l i l ~0g1 , I I I I I ; I \ I ~ I ~ ~1112 :III~, w l ) : i r : ~ l i ~ I~I ~gI I I I ~ I I I ~ I I ( , ~ > ~ I I, ,I I I, \ , < , ' I ' I ~ I ~ I ~[or, I I ~ yI .5 - I O O 57 (Sl,t, l~rl~lio~~, 49 ( s r e I M P K P S u w of, I 18, I 10, 120-128 sros) A ~rtic~ilatol-s, (111 ( w e ~ K ' l . l ~ l ~ l .IA N'(l; ) I)ellt11rcs, R:Iw.. iol- ( s t c I ) ~ ~ N ' I ' U K I I S ) (':~\ts, 011 ( w e .\KI~CUI.ATIN~:) ILI.\IRIS, COY5 I . 0 1 2 q 0 , 297 11;111:111,118, 129 MECII.\SIC Plain lit~c,articl~lator,011, I 10-1 17 l)tat~t:~II , : I ~ > o I - : I I I I (lefi~~etl, I-~, xi ( w e casts, attnchrnrnt of, 113-115 ~l'l~CllN1C'l~\\~) c a u t i o l ~ sin, r I r Ml r l ~ t ~ i r e ( s 66-69 ), vocational analysis of, xviii-xxv c a u t i ~ ~ nill, s 66 hl E'C4.1. iob appraisal ol, 7 0 Denture, 235 ( w e DENTURE) procedure for, 66 Melted, safety inst. for, xxviii cli~estic~ns 011, 67, 68 MODELING COMPOIJSD, 48, 49 r u g a r , 66 Riteplates of (see BITEPI..~TI:S) tools for, 65 Ingredients of, 49 Specifications for, A.1>..4., 108, loo MORPHOLOGY, I 33- 146 l'.\CKING IJel~turcs,v ~ ~ l r a n i t ezo7-zj5 , 'I'eeth, Artificial, 131-146 (see T E K I I I ) caution, ~ q r caution5 for, 215-217 c h a r a c t r r i ~ t i c s of, r33-i42 (src d e n t u r e bases, 228-229 TEETIL) etluipmrlrt for, 215 ;ol> ;~l)l)raisal011, 132 full dentnrrs, 223-228 jol, a p p r a i m h f , 232 j)roc.ctlr~~-c., 13 I materials for, 215 clltrstions 011. 132 partial d e l ~ t u r e s ,228 MoIIN'I'IN(: A ~ l : ~ l ~ t ; ~ lAArti