lab procedures in complete denture prosthodontics / orthodontic courses by indian dental academy

LAB PROCEDURES IN COMPLETE DENTURE FABRICATION

INDIAN DENTAL ACADEMY

Leader in continuing dental education www.indiandentalacademy.com

www.indiandentalacademy.com

CONTENTS• Introduction• Pouring the diagnostic impression & Making the diagnostic cast• Pouring the primary impression Making the primary cast • Fabrication of impression tray• Final impression,Beading,Boxing & pouring• Record base fabrication • Occlusion rims• Mounting the casts onto the articulator

• Arranging & Articulating the Artificial teeth -Anterior teeth arrangement

-posterior teeth arrangement• Waxing & Carving the trial denture• Processing the waxed up dentures• Deflasking the processed dentures• Lab remounting • Finishing & polishing • Duplicating dentures• Review of Literature • Summary & conclusion References

INTRODUCTION

POURING THE DIAGNOSTIC IMPRESSION & MAKING THE DIAGNOSTIC CAST

• Preliminary care of the impression…

• Pouring the impression …

• Separate the cast & Trim the excess

IDEAL REQUIREMENTS OF THE CAST

• Cast surface should be free of voids ,nodules.

• Extend sufficiently…• Land area…• Base of the cast…

Purpose of making the diagnostic cast

• To measure the depth & extent of undercuts. • Determine the path of insertion..• Plan the preprosthetic surgeries…• Evaluate size & contour of the arch…

Surveying the diagnostic castSurveying the diagnostic cast

• Measuring depth of undercut.-Mounting the cast

-Tilting the cast- to change the path of insertion.-Mark the height of contour.

-Mark the depth of undercut. -Mock surgery is done ..

POURING THE PRIMARY CAST

• Preliminary care of the impression…• Pour the impression…

FABRICATION OF THE SPCIAL TRAY

• Custom tray :(GPT)An individualized tray made on a cast recovered

from the preliminary impression. Used for making final impression.

• A custom made device prepared for a particular patient which is used to carry, confine & control an impression material while making an impression.

IDEAL REQUIREMENTS OF THE SPECIAL TRAY

• Rigid• Dimensionally stable..• Should not react with impression material.• Simple method of fabrication• 2mm in thickness & 2 mm short of the

sulcus depth.

MATERIAL USED

• Shellac • Auto polymerizing acrylic resin• Heat cured acrylic resin• Vacuum formed thermoplastic resin• Type II impression compound

FABRICATION OF AUTOPOLYMERIZING RESIN SPECIAL TRAY

• PROCEDURE: • Mark the outline of relief,spacer.• Adapt relief wax.• Block out..• Adapt spacer..• Apply separating media.• Sprinkle on or dough method.• Make handle.• Trim…

SPRINKLE ON METHOD

•Advantages•Dis advantages

DOUGH METHOD

•Advantages.

•Disadvantages

VACUUM ADAPTED THRMOPLATIC RESIN

• Procedure• Spacer..• Center the cast on the vacuum adapter plate.• Place the resin sheet in the heating frame & rotate

the heating unit into position.• Heating until sheet sags.• Lower the frame & resin sheet onto the cast & start

vacuum adaptation. .• Trim the excess remove from the cast &final trim .• Adapt handle

SHELLAC TRAY

• Procedure• Advantages.• Disadvantages.

FINAL IMPRESSION BEADING, BOXING & POURING

• WAX BOXING METHOD-Procedure

-Advantages

BOLOURI, TERENE, MAYNARD GOWRYLOK TECHNIQUE(1975)

• Pour the plaster base & lightly seat the impression into the plaster leaving the peripheral turn at least 4mm above.

• Trim the excess leaving 5mm wide & 4mm below the impression

• Adapt modeling clay , plasticine.• Apply separating media.• Boxing.

Plaster & pumice mix boxing method.

Caulking compound & Paddle boxing Method Blank 1961.

• Beading with Caulking compound rope.

• Boxing with metal strip secure with rubber band seal to the wax paddle.

• Pour the impression.

• A study was conducted by Jhon M Young (1975) He made the stone casts & test specimens in two methods. One group fluid dental stone cast was allowed to set vertically against the impression,other group allowed to set against impression inverted.Rough grainy appearing cast surfaces with samples set against inverted impression.

• He concluded that stone should be allowed to set against impression material, So that the contaminants & liquid rise to the surface away from the impression surface.

RECORD BASE

• Ideal requirements…Elder• Adaptation• Border form• Rigidity• Simple ,quick , inexpensive fabrication.• Means for recording jaw relation , teeth arrangement.• Kenneth added----Not to abrade the cast

-Take advantage of undercut -Bond with block out

material.www.indiandentalacademy.com

FABRICATION OF RECORD BASE WITH AUTOPOLYMERIZING RESIN

• Sprinkle on method• Dough method• Confined dough methods.

• A technique by AssadzadeYarmond(1975) --Block out…

--Adapt wax sheet on the cast & duplicate --Place acrylic mix on the mold & close with the

cast.• Advantages ---

• Disadvantages---

Method given by Levere , Freda

FLUID RESIN BASEPLATES

• Heat cure acrylic base plate• Shellac base plate.• Stabilized shellac base plates• Vacuum adapted

OCCLUSION RIMS• Occlusion rim is defined as the “Occluding surfaces built

on permanent denture bases for the purpose of making maxilomandibular relation records”.

• 4 basic factors to be considered are-- • 1) Relationship of natural teeth to alveolar bone• 2) Relationship of occlusion rim to the alveolar bone• 3) Fabrication technique..• 4) Clinical considerations

MOUNTING THE CASTS ON TO THE ARTICULATOR

• The laboratory procedure of attaching the maxillary & mandibular casts to an articulator.

MOUNTING ON TO HANAU ARTICULATOR

Procedure…• Adjust the horizontal condylar guidance.• Adjust the incisal pin..

• Attach the mounting plate.

• Face bow record transferred.• Mounting guide as in twirl bow & spring bow,Anterior elevator , transfer

jig used with kinematic face bow.• Attach the cast support to the lower member of the articulator .• Attach maxillary cast with the plaster. • Mount the mandibular cast….• Horizontal condylar inclination determined with the protrusive record.

MOUNTING ON TO THE WHIPMIX ARTICULATOR

• Adjust the intercondylar distance by removing the condylar elements &using the spacers on the condylar shaft.

• Adjust the horizontal condylar inclination.• Attach mounting plates & plastic incisal guide table.• Face bow record transferred.• Mount the maxillary cast with dental plaster.• Mount the mandibular cast.

MOUNTING WITH THE SPLIT REMOUNTING PLATES

ARRANGING & ARTICULATING THE

ARTIFICIAL TEETH • ARTIFICIAL TEETH…..• Metal insert resin teeth -- Improved occlusal wear

resistance .• Mechanical bonding• Maintains vd

• Masticatory efficiency.

ANTERIOR TEETH ARRANGEMENT

• ARRANGING MAXILLARY TEETH.• Definite anatomic guides used…• Incisive papilla-• The relationship of central incisor with the reflection

of tissue under the lip.

• Midsagittal suture

• Antero posterior positioning of the teethAnatomical landmarks…

• Labio lingual inclination • Mesiodistal inclination• Rotational positions from the incisal aspect• Supero inferior position• Irregularities

ARRANGING THE POSTERIOR TEETH

• Surveying the mandibular cast…• ARRANGING 33 degree ANATOMIC TEETH..

• I premolar long axis perpendicular to the occlusal plane• II premolar• I molar mb & ml cusp touch the occlusal plane , db 0.5

mm & ml 0.75 mm raised.• II molar

ARTICULATION OF THE MANDIBULAR TEETH

• I MOLAR---• In centric occlusion• Working occlusion- buccal cusps occlude. -

Distal facet of max. I PM occlude with mesiobuccal marginal ridge of mand. I molar.

• II MOLAR• In centric occlusion• Working occlusion MB cuspof mandibular II molar occludes with

distal

• II PREMOLAR• Centric occlusion• Working occlusion

• I PREMOLAR• Centric occlusion• Working occlusion

• Arrange mandibular teeth first• I & II Premolar—central fosse in line

with the antero posterior reference line.• I Molar-- mesial cusp on plane established

by anterior & bicuspids. Distal cusp raised by 0.5 mm.

• II Molar…• Grinding of transverse ridge for mesio

distal unlocking of cusped teeth & buccolingual inclines.

• ARRANGING MAXILLARY TEETH

• Modified by grinding.• I PREMOLAR—• II PREMOLAR– Lingual cusp occludes with distal

marginal ridge of II PM & mesial marginal ridge of I molar.

• I MOLAR • II MOLAR• Balancing of the occlusion—

-Selective grinding for centric contact--Selective grinding for working & balancing contacts.--Selective grinding for protrusive balance.

NON ANTOMIC TEETH ARRANGEMENT

• In flat linear occlusion-- long axis at right angles to occlusal plane& touch the occlusal plane.

• Bilateral balance– arrange mandibular teeth & occlude the maxillary teeth .

WAXING THE DENTURES

• The form of the polished surface of the dentures affects esthetic & retentive quality.

• PROCEDURE• Adapt softened roll of wax on the facial surface & contour.• Carving to produce gingival bulge &root prominences.• Palatal surface…• Lingual surface • Stippling…

FLASKING THE WAXED UP DENTURES

• The waxed up dentures are invested & mold is created within the flask.

• PROCEDURE:

• WAX ELIMINTION

COMPRESSION MOLDING TECHNIQUE

FLUID RESIN COMPLETE DENTURE

• CURING-- the packed heat cure acrylic

DEFLSKING

LABORATORY REMOUNTING OF THE DENTURES

• Serves as an accurate , convenient & time saving method of reorienting the processed dentures on the articulator for occlusal correction.

• Construction of the remounting casts.• Preserving the orientation relation Index. • The maxillary denture with the cast placed in the plaster

index & attached to the articulator.

FINISHING & POLISHING OF THE DENTURES

• Remove the cast ..• Shell blaster to remove the stone from the interior surface.• Trim the Excess…• Check for the nodules .• Relive the frenii.• Finishing of lingual border & palatal surface.• Pumice the dentures with rag wheel inaccessible areas use

prophy cup.• Polishing the teeth.

DUPLICATIING DENTURES

REVIEW OF THE LITERATUREREVIEW OF THE LITERATURE

• A study was conducted by Keith R Marcroft, Tencate,William Hyrst(1961).

• They fabricated 106 complete dentures with layered silicone rubber investing on the upper half of the mold & 50 with all gypsum investment.

• They concluded that the wax dose not penetrate the silicone rubber mold so separating media not required. Reproduces carving contours accurately . Requires less finishing &polishing.

• A study was conducted by A . Grant (1962)• He concluded that -- • The first pour of the investment dose not

affect the position of the tooth.• The second pore dose not affect relative

position of tooth & cast.• Tooth movement can be minimized by

clamping the flask after investing.www.indiandentalacademy.com

• Duncan H. Wallace (1964)gave the technique to use the Gold occlusal surfaces in resin teeth.

• He concluded that chewing efficiency increased & natural feeling. It can be used in patients with decreased interarch space.

• A study was conducted by Philip Schiffman (1964) he studied the relation of the of the canine teeth to incisive papilla in 507 casts .

• He concluded that the position pf the incisive papilla remains fairly constant. In 78.3% of he casts the line passing through the center of the incisive papilla joining the canine cusp tips is perpendicular to long axis of the cast. In 92% of the casts line passed 1mm anterior or posterior to it.

A technique of restoring the resin teeth with silver amalgum restoration was given by John B. Sowter,Robert E .Basd(1968).

• They Concluded that the efficiency of resin posterior teeth increased & also prevent wear of the teeth.

Method of reducing the shifting of the teeth during processing was given by Robert G. Vig (1975).

• He showed that extension of waxed up denture onto the posterior aspect of the cast decreased the shifting of the posterior teeth during processing.

• A study was conducted by John J. Sharry in (1977)

• He processed the denture bases by 3 techniques & concluded that all techniques showed dimensional changes .

• A study was conducted by Gregory Polyzois et.al (1985).

• He processed the waxed denture bases with 3 curing cycles.

• He concluded that curing for 1.5 hr at 60degree c. , 2.5hr at 75 de.c,100 degree c. for 1hr produces higher degree of curing of acrylic resin

• A study wa conducted by Dr Jayavikram under the able guidance of Sir (2001). It was concluded that tooth movement observed during flasking & packing . The thickness of the flash less with Lucitone as compared to conventional heat cure acrylic.

CONCLUSION

References• Boucher’s Prosthodontic Treatment for edentulous patients 9th edition.• Charles M.Heart well’s syllabus of complete denture prosthodontics.• DCNA Complete Dentures Robert Engelmeier 40.;1:Jan 1996• Surface characteristic of dental stone with impression orientation John

M Young J:P:D;19975:3:33:336• Murrow,Rudd,Rhods.Dental laboratory procedure complete denture.• Sheldon Winkler’s Essentials of complete denture Prosthodontics 2nd

edition.• Skinner’s Science of Dental Materials• Zarb-Bolender’s Prosthodontic Treatment for edentulous patients 12th

edition .• The use of gold occlusal surface in complete & partial dentures by

Duncan wallace J.P.P:1964:326:333.• Effect of C yring cycles & denture base shape on the degree of cure of

Acrylic resin denture base Gregory Polyzois etc..all 1985:9:11. Quintessence of Dental Technology.

• Comparision of Denture base processing technique part II.Dimensional changes due to processing ,by John.J.Sharry.J.P.D:1977:37:4:456.

• Fluid denture resin processing in a rigid mold by Frank.f.Koblitz.etc al J.P.D:1973:30:339 .

• Use of layered silicone Rubber mold technique for denture processing by Keith.R.Marcoft et al.J;P;D1961;30;657:659

• The relation of marillary canines to the ineisive papilla Philiff Schiffman J;P;D:1964:14:469.

• Method of reducing the shifting of teeth in denture processing by Robert.G.Vig J.P.D:1975:33:34.

• Study conducted by Philip Schiffmann in J.P.D:1964:14:469.

Thank you

For more details please visit www.indiandentalacademy.com

lab procedures in complete denture prosthodontics / orthodontic courses by indian dental academy

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