Wax patterns/ dentistry course in india

WAX PATTERNSWAX PATTERNSINDIAN DENTAL ACADEMY

Leader in continuing dental education www.indiandentalacademy.com

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INTRODUCTIONINTRODUCTION

The wax pattern is a precursor of the The wax pattern is a precursor of the finished cast restoration that will be placed finished cast restoration that will be placed on the prepared toothon the prepared tooth

In as much as the wax pattern will be In as much as the wax pattern will be duplicated exactly through the investing duplicated exactly through the investing and casting technique, the final restoration and casting technique, the final restoration will be no better than its wax pattern i.e., will be no better than its wax pattern i.e., errors and oversights in the wax pattern errors and oversights in the wax pattern will only be perpetuated in the casting.will only be perpetuated in the casting.


Methods of fabrication of wax Methods of fabrication of wax patternpattern

Direct method : in which, the pattern is Direct method : in which, the pattern is waxed on the prepared tooth, in the waxed on the prepared tooth, in the mouthmouth

Indirect method: in which, the pattern is Indirect method: in which, the pattern is waxed on a stone cast made from an waxed on a stone cast made from an accurate impression of the prepared toothaccurate impression of the prepared tooth

Advantages of indirect technique – affords Advantages of indirect technique – affords an opportunity for visualization of an opportunity for visualization of restoration and ready access to waxing restoration and ready access to waxing the marginsthe margins


WAXES USEDWAXES USED

Direct technique – type I wax is usedDirect technique – type I wax is used Indirect technique – type II wax is Indirect technique – type II wax is

used – slightly lower melting used – slightly lower melting temperature than type Itemperature than type I

The wax used should meet ADA The wax used should meet ADA specification no 4specification no 4


IDEAL REQUIREMENTSIDEAL REQUIREMENTS

It must flow readily when heated, without It must flow readily when heated, without chipping, flaking, or losing its smoothnesschipping, flaking, or losing its smoothness

When cooled, must be rigidWhen cooled, must be rigid It must be capable of being carved It must be capable of being carved

precisely without chipping, distorting or precisely without chipping, distorting or smearingsmearing

The wax should of some color, such as The wax should of some color, such as blue, green, or red that will contrast with blue, green, or red that will contrast with and be easily distinguishable from the and be easily distinguishable from the stone diestone die


WAX PATTERN FABRICATIONWAX PATTERN FABRICATION ARMAMENTARIUM:ARMAMENTARIUM:

PKT [Thomas] waxing instruments [no.1, no.2, no. 3, no 4, PKT [Thomas] waxing instruments [no.1, no.2, no. 3, no 4, and no.5]and no.5]

Beavertail burnisherBeavertail burnisher No 7 wax spatulaNo 7 wax spatula Sable brushSable brush No.2 pencilNo.2 pencil Laboratory knife with no.25 bladeLaboratory knife with no.25 blade Cotton pliersCotton pliers Bunsen burnerBunsen burner Inlay casting waxInlay casting wax Zinc stearate powderZinc stearate powder Die lubricantDie lubricant


Wax is added by heating the instrument in Wax is added by heating the instrument in the bunsen flame, touching it to the wax, the bunsen flame, touching it to the wax, and quickly reheating it shank in the and quickly reheating it shank in the flame.flame.

Wax flows away from the hottest part of Wax flows away from the hottest part of the instrument, so if the shank is heated, the instrument, so if the shank is heated, a bead of wax will flow off the tip.a bead of wax will flow off the tip.

However, if the tip is heated, the wax will However, if the tip is heated, the wax will flow up the shank of the instrument.flow up the shank of the instrument.


The following sequence is recommended The following sequence is recommended for wax pattern fabrication:for wax pattern fabrication:

Internal surface.Internal surface. Wax pattern removal and evaluation.Wax pattern removal and evaluation. Proximal surfaces.Proximal surfaces. Axial surfaces.Axial surfaces. Incisal/occlusal surface.Incisal/occlusal surface. Margin finishing.Margin finishing.


Internal surface: the wax must reproduce Internal surface: the wax must reproduce all the retentive features of the all the retentive features of the restoration.restoration.


Wax pattern removal : Wax pattern Wax pattern removal : Wax pattern should be allowed to cool thoroughly should be allowed to cool thoroughly before the coping is removed from the before the coping is removed from the die.die.


Wax pattern evaluation: The objective of Wax pattern evaluation: The objective of the first waxing step is a perfectly the first waxing step is a perfectly adapted reproduction of the prepared adapted reproduction of the prepared tooth surfaces.tooth surfaces.


Coping fabricationCoping fabrication

First step – fabrication of a thin First step – fabrication of a thin coping / thimble, on the diecoping / thimble, on the die

It is made of wax, but heated resin It is made of wax, but heated resin sheets can also be usedsheets can also be used

Vaccum adapted polystrene and Vaccum adapted polystrene and pressure formed polypropylene have pressure formed polypropylene have been used for making metal ceramic been used for making metal ceramic crown patternscrown patterns


It serves as a foundation for the axial It serves as a foundation for the axial contours and occlusal morphologycontours and occlusal morphology

To prevent the wax from sticking to To prevent the wax from sticking to the stone die, it is coated with a die the stone die, it is coated with a die lubricant and allowed to soak for lubricant and allowed to soak for several minutes. Repeat application several minutes. Repeat application if the die appears dry. Remove any if the die appears dry. Remove any excess lubricant with a gentle stream excess lubricant with a gentle stream of compressed airof compressed air


Flow wax over the surface of the Flow wax over the surface of the preparation on the die , using quick preparation on the die , using quick strokes of a hot no 7 wax spatula. strokes of a hot no 7 wax spatula. Overlap and remelt the margins of Overlap and remelt the margins of wax already placed on the die – to wax already placed on the die – to prevent flow lines or voids.prevent flow lines or voids.

Dipping the die into a small metal Dipping the die into a small metal container filled with molten wax is container filled with molten wax is another method that can be used for another method that can be used for developing a uniform, thin initial developing a uniform, thin initial coping of wax on the diecoping of wax on the die


To ensure that the finished restoration To ensure that the finished restoration will have adequate proximal contact will have adequate proximal contact with the adjacent teeth, the wax with the adjacent teeth, the wax pattern should be slightly oversized pattern should be slightly oversized mesiodistally – to provide enough bulk mesiodistally – to provide enough bulk in the contact areas to allow casting, in the contact areas to allow casting, finishing, and polishing without finishing, and polishing without creating an open contact in the creating an open contact in the finished restorationfinished restoration

The best way for achieving this is to The best way for achieving this is to remove a smal amount of stone from remove a smal amount of stone from the proximal surfaces of the cast on the proximal surfaces of the cast on either side of the prepared tooth either side of the prepared tooth


Axial contoursAxial contours

The proximal contacts of posterior teeth are The proximal contacts of posterior teeth are located in the occlusal third of the crowns located in the occlusal third of the crowns except between the maxillary first and except between the maxillary first and second molars, which is located in the second molars, which is located in the middle thirdmiddle third

The contact must be more than just a point The contact must be more than just a point occlusogingivally, but it must not extend far occlusogingivally, but it must not extend far enough cervically to encroach on the enough cervically to encroach on the gingival embrasure.gingival embrasure.

The axial surface of the crown cervical to The axial surface of the crown cervical to the contact point should be flat or slightly the contact point should be flat or slightly concaveconcave


A flat contour may be the optimal shape as A flat contour may be the optimal shape as it is the easiest to floss. it is the easiest to floss.

Proximal contacts are located slightly to the Proximal contacts are located slightly to the facial aspect of the middle of the posterior facial aspect of the middle of the posterior teeth, except between the maxillary first teeth, except between the maxillary first and second molars, which is located in the and second molars, which is located in the center faciolinguallycenter faciolingually

Contacts that are too narrow allow fibrous Contacts that are too narrow allow fibrous foods to wedge between the teeth, while foods to wedge between the teeth, while contacts that are wide facioligually do not contacts that are wide facioligually do not adequately deflect food from the gingival adequately deflect food from the gingival tissuetissue


The facial and lingual contours should be The facial and lingual contours should be in harmony with those of the adjacent in harmony with those of the adjacent teethteeth

Height of contour on the facial surface of Height of contour on the facial surface of all posterior teeth extends horizontally all posterior teeth extends horizontally 0.5mm beyond the plane of the tooth. 0.5mm beyond the plane of the tooth.

On the lingual surface of the maxillary On the lingual surface of the maxillary teeth and mandibular first premolars, the teeth and mandibular first premolars, the height of contour extends about 0.5mm, height of contour extends about 0.5mm, but it increases to 0.75 mm on the but it increases to 0.75 mm on the mandibular second premolar and nearly mandibular second premolar and nearly 1mm on mandibular molars1mm on mandibular molars


Incisal/occlusal surface: Opposing incisors Incisal/occlusal surface: Opposing incisors should make even contact during should make even contact during protrusive movements but not during protrusive movements but not during lateral excursions. The cusps and ridges lateral excursions. The cusps and ridges of the occlusal surfaces should be shaped of the occlusal surfaces should be shaped as to allow even contact with the as to allow even contact with the opposing teeth while stabilizing the teeth opposing teeth while stabilizing the teeth and directing the forces along the long and directing the forces along the long axes of the teeth.axes of the teeth.


Margin finishing: For finalizing and Margin finishing: For finalizing and adaptation, the margins should be adaptation, the margins should be reflowed and refinished immediately prior reflowed and refinished immediately prior to investing the wax pattern.to investing the wax pattern.


EMERGENCE PROFILEEMERGENCE PROFILE STEIN and KUWATA described emergence STEIN and KUWATA described emergence

profile as the part of the axial contour that profile as the part of the axial contour that extends from the base of the gingival sulcus extends from the base of the gingival sulcus past the free margin of the gingivapast the free margin of the gingiva

the emergence profile extends to the height the emergence profile extends to the height of contour, producing a straight profile in the of contour, producing a straight profile in the gingival third of the axial surfacegingival third of the axial surface

Production of a straight profile should be the Production of a straight profile should be the treatment objective in restoring a tooth, as treatment objective in restoring a tooth, as it facilitates access for oral hygiene it facilitates access for oral hygiene measuresmeasures


The most common error relating to The most common error relating to axial contour is the creation of a axial contour is the creation of a bulge or excessive concavitybulge or excessive concavity

Overcontoured restorations with Overcontoured restorations with large convexities promote the large convexities promote the accumulation of food debris and accumulation of food debris and plaque, and gingival inflammation plaque, and gingival inflammation results.results.


OCCLUSAL MORPHOLOGYOCCLUSAL MORPHOLOGY

Waxing of the occlusal surface is deferred Waxing of the occlusal surface is deferred until the axial surfaces are essentially until the axial surfaces are essentially completecomplete

Functional cusps – palatal cusps of the Functional cusps – palatal cusps of the maxillary posterior teeth and buccal cusps maxillary posterior teeth and buccal cusps of the mandibular posterior teeth – help in of the mandibular posterior teeth – help in grinding of foodgrinding of food

Non – functional cusps – buccal cusps of Non – functional cusps – buccal cusps of the maxillary molars and the lingual cusps the maxillary molars and the lingual cusps of the mandibular molars – act as a rim of of the mandibular molars – act as a rim of a pestle to prevent food from overflowinga pestle to prevent food from overflowing


Classification of occlusal arrangementsClassification of occlusal arrangements

Cusp -fossaCusp -fossa Cusp –marginal ridgeCusp –marginal ridge

Location of occlusal Location of occlusal contact on opposing contact on opposing toothtooth

Occlusal fossaOcclusal fossa Occlusal fossae and Occlusal fossae and marginal ridgesmarginal ridges

Relation with Relation with opposing teethopposing teeth

Tooth –to - tooth Tooth –to - tooth Tooth-to-two-teethTooth-to-two-teeth

advantagesadvantages Occlusal forces Occlusal forces directed parallel to directed parallel to long axis of tooth- long axis of tooth- very little lateral very little lateral stressstress

Most natural type of Most natural type of occlusion -95% of occlusion -95% of adults. Can be used adults. Can be used for single restorationsfor single restorations

disadvantagesdisadvantages Rarely found in Rarely found in natural teeth – used natural teeth – used only when restoring only when restoring several contacting several contacting teethteeth

Food impaction and Food impaction and displacement of teeth displacement of teeth may arise if the may arise if the functional cusps functional cusps wedge into the lingual wedge into the lingual embrasureembrasure

applicationsapplications Full mouth Full mouth reconstructionreconstruction

Most cast restorationsMost cast restorationswww.indiandentalacademy.comwww.indiandentalacademy.com

Mandibular cusp placementMandibular cusp placement

Mandibular buccal cuspsMandibular buccal cusps Maxillary occlusal Maxillary occlusal surfacessurfaces

Cusp-marginal ridgeCusp-marginal ridge Cusp-fossaCusp-fossa

First premolarFirst premolar M marginal ridge of 1M marginal ridge of 1stst PMPM

M fossa of the 1M fossa of the 1stst PM PM

Second premoarSecond premoar D marginal ridge of 1D marginal ridge of 1stst PM and M marginal ridge PM and M marginal ridge of 2of 2ndnd PM PM

M fossa of the 2M fossa of the 2ndnd PM PM

MB cusp of first molarMB cusp of first molar D marginal ridge of 2D marginal ridge of 2ndnd PM and M marginal ridge PM and M marginal ridge of 1st Mof 1st M

M fossa of the 1M fossa of the 1stst M M


DB cusp of first molarDB cusp of first molar C fossa of the 1C fossa of the 1stst molar molar C fossa of the 1C fossa of the 1stst M M

D cusp of first molarD cusp of first molar Usually not functionalUsually not functional D fossa of the 1D fossa of the 1stst M M

MB cusp of 2MB cusp of 2ndnd molar molar D marginal ridge of 1D marginal ridge of 1stst M M fossa of the M M fossa of the 22NDND M M

& M marginal ridge of 2& M marginal ridge of 2ndnd M M

DB cusp of 2DB cusp of 2ndnd molar molar C fossa of the 2C fossa of the 2ndnd molar molar C fossa of the 2C fossa of the 2ndnd MM

D cusp of 2D cusp of 2ndnd molar molar Usually not presentUsually not present Usually non-Usually non-functionalfunctional


MAXILLARY CUSP MAXILLARY CUSP PLACEMENTPLACEMENT

Maxillary lingual Maxillary lingual cuspscusps

Mandibular occlusal Mandibular occlusal surfacessurfaces

Cusp-marginal Cusp-marginal ridgeridge

Cusp-fossaCusp-fossa

First PMFirst PM D fossa of 1D fossa of 1stst PM PM D fossa of 1D fossa of 1stst PM PM

SECOND PMSECOND PM D fossa of 2D fossa of 2ndnd PM PM D fossa of 2D fossa of 2ndnd PM PM

ML cusp of 1ML cusp of 1stst M M C fossa of 1C fossa of 1stst M M C fossa of 1C fossa of 1stst M M

DL cusp of 1DL cusp of 1stst M M D marginal ridge of D marginal ridge of 11stst M & M marginal M & M marginal ridge og 2ridge og 2ndnd M M

D fossa of 1D fossa of 1stst M M

ML cusp of 2ML cusp of 2ndnd M M C fossa of 2C fossa of 2NDND M M C fossa of 2C fossa of 2ndnd M M

DL cusp of 2DL cusp of 2ndnd M M D marginal ridge of D marginal ridge of 22ndnd M M

D fossa of 2D fossa of 2ndnd M Mwww.indiandentalacademy.comwww.indiandentalacademy.com

CUSP-MARGINAL RIDGE CUSP-MARGINAL RIDGE ARRANGEMENTARRANGEMENT

This technique was originally devised This technique was originally devised by EV Payne. It was the first wax-by EV Payne. It was the first wax-added technique for functional added technique for functional waxingwaxing


CUSP-MARGINAL RIDGE FOR CUSP-MARGINAL RIDGE FOR MAXILLARY TEETH MAXILLARY TEETH


Gnathologic Concept: Gnathologic Concept: TripodismTripodism

A cusp fossa relation in which the A cusp fossa relation in which the centric cusp makes contact with the centric cusp makes contact with the occlusal fossa of the opposing tooth at occlusal fossa of the opposing tooth at three points of each cusp in each three points of each cusp in each opposing fossaopposing fossa

The three contact points are the three The three contact points are the three ridges which for the fossa against the ridges which for the fossa against the opposing centric cusp.opposing centric cusp.

Achieved because of the rounded Achieved because of the rounded nature of the cusp ridgesnature of the cusp ridges


Tripod contacts are immediately Tripod contacts are immediately

separated when the mandible performs separated when the mandible performs

lateral excursions and protrusive lateral excursions and protrusive

excursionsexcursions

The centric contacts are immediately The centric contacts are immediately

discluded into groove or into discluded into groove or into

interproximal embrasuresinterproximal embrasures


Advantages of Tripodism:Advantages of Tripodism:– Minimum wear of the cusps tips and cusp shapes Minimum wear of the cusps tips and cusp shapes

is maintainedis maintained → prevents the tip of a cusp to come → prevents the tip of a cusp to come

into contact with the fossa of the opposing toothinto contact with the fossa of the opposing tooth

– Gives Stability to Centric OcclusionGives Stability to Centric Occlusion → forces are → forces are

directed near the centre of the toothdirected near the centre of the tooth

– Distributes Forces on an Individual ToothDistributes Forces on an Individual Tooth → Allows → Allows

a multiplicity of pin point contactsa multiplicity of pin point contacts

– Soft Tissue ProtectionSoft Tissue Protection → minimum lateral force → minimum lateral force

placed on the tooth is better tolerated by the placed on the tooth is better tolerated by the

periodontal membraneperiodontal membrane

– Keeps the Interproximal Contacts IntactKeeps the Interproximal Contacts Intact


Additive TechniqueAdditive Technique


Additive techniqueAdditive technique

Provides an organized step-by-step Provides an organized step-by-step procedure to develop the occlusal procedure to develop the occlusal anatomic formanatomic form

Better understanding of the effects of Better understanding of the effects of articulation on the individual articulation on the individual elements of the occlusal form than elements of the occlusal form than the carving techniquethe carving technique


Step 1: Buildup of ConesStep 1: Buildup of Cones

Centric Cusp tips are developedCentric Cusp tips are developed Centric cones placed at the Centric cones placed at the

appropriate mesiodistal position on appropriate mesiodistal position on the BO or LO lines.the BO or LO lines.

Diameter of the base of the cone is Diameter of the base of the cone is one third of the mesiodistal diameter one third of the mesiodistal diameter of the respective cuspof the respective cusp


For a Maxillary 1For a Maxillary 1stst Molar… Molar…

Give sufficient space to wax the centric Give sufficient space to wax the centric cusp ridge and triangular ridgescusp ridge and triangular ridges

Wax the mesiolingual cusp to contact a Wax the mesiolingual cusp to contact a flat area located in the central fossa of the flat area located in the central fossa of the mandibular 1mandibular 1stst molar molar

Then wax the distolingual cusp to contact Then wax the distolingual cusp to contact the marginal ridge of the mandibular 1the marginal ridge of the mandibular 1stst molarmolar

DEVELOP THE CONTACTS ONLY ON THE DEVELOP THE CONTACTS ONLY ON THE CUSP TIPSCUSP TIPS


Step 2: Mesial and Distal Step 2: Mesial and Distal Marginal RidgesMarginal Ridges

Develop the mesial and distal marginal Develop the mesial and distal marginal ridges in a triangular shape with the apex ridges in a triangular shape with the apex on the triangle at the occlusal piton the triangle at the occlusal pit

Mesial marginal ridge should contact the Mesial marginal ridge should contact the opposing cusp on the central fossa lineopposing cusp on the central fossa line

Distal marginal ridge should be formed to Distal marginal ridge should be formed to the same height as the adjacent marginal the same height as the adjacent marginal ridges.ridges.

From occlusal view: marginal ridges From occlusal view: marginal ridges should converge to the lingual, creating a should converge to the lingual, creating a greater lingual than buccal embrasure.greater lingual than buccal embrasure.


Step 3: Central Fossa Contact Step 3: Central Fossa Contact AreaArea

Contact area should have a superior Contact area should have a superior surface that is slightly convex with surface that is slightly convex with the highest point at the center.the highest point at the center.

From occlusal view: area is From occlusal view: area is rhomboidal shaped with each apex rhomboidal shaped with each apex fitting into a development occlusal fitting into a development occlusal groovegroove

Mesiodistal and buccal diameters Mesiodistal and buccal diameters should be approx 2mmshould be approx 2mm


Step 4: Lingual Cusp RidgesStep 4: Lingual Cusp Ridges

Should have a definite convexity between Should have a definite convexity between the lingual height of contour and the cusp tipthe lingual height of contour and the cusp tip

From lingual View: Should be triangular with From lingual View: Should be triangular with apex at the cusp tip and base at the wax apex at the cusp tip and base at the wax copingcoping

SHOULD NOT MODIFY THE EXISTING SHOULD NOT MODIFY THE EXISTING CUSP TIPS – THEY DO NOT CONTACT CUSP TIPS – THEY DO NOT CONTACT

THE OPPOSING TEETH IN CENTRIC AND THE OPPOSING TEETH IN CENTRIC AND ECCENTRIC POSITIONSECCENTRIC POSITIONS


Step 5: Mesial and Distal Step 5: Mesial and Distal Lingual Cusp RidgesLingual Cusp Ridges

Should not alter the cusp tipShould not alter the cusp tip Should provide physiologic occlusal Should provide physiologic occlusal

embrasures and proper transitional embrasures and proper transitional line angles.line angles.

Most not contact the opposing toothMost not contact the opposing tooth Should leave sufficient space for the Should leave sufficient space for the

triangular and oblique ridges.triangular and oblique ridges.


Step 6: Functional Cusp Step 6: Functional Cusp Triangular RidgesTriangular Ridges

Extends from the cusp tip to the Extends from the cusp tip to the central fossacentral fossa

Should be convex from the cusp tip Should be convex from the cusp tip to the central fossa and from the to the central fossa and from the mesial to the distal aspect.mesial to the distal aspect.

Should have a greater mesiodistal Should have a greater mesiodistal width at the central fossa than at the width at the central fossa than at the cusp tip and should slope down from cusp tip and should slope down from the cusp tip to the fossa.the cusp tip to the fossa.


Supplemental grooves should be Supplemental grooves should be developed to separate the mesial developed to separate the mesial and distal aspects of the lingual cusp and distal aspects of the lingual cusp ridges from the respective ML and DL ridges from the respective ML and DL triangular ridges.triangular ridges.


Step 7: Non-Centric Cusp Step 7: Non-Centric Cusp tipstips

Should be developed on the corresponding Should be developed on the corresponding BO lineBO line

Should vertically and horizontally overlap the Should vertically and horizontally overlap the opposing tooth in the occluded position.opposing tooth in the occluded position.

In laterotrusion these cusps are developed to In laterotrusion these cusps are developed to pass through the embrasures and grooves of pass through the embrasures and grooves of the opposing teeth without contact.the opposing teeth without contact.

Sufficient room should be provided to allow Sufficient room should be provided to allow wax up of the surrounding cuspal ridges.wax up of the surrounding cuspal ridges.


Step 8: Buccal Cusp RidgesStep 8: Buccal Cusp Ridges

Should blend into the buccal cusp Should blend into the buccal cusp conescones

Should be triangular with apex at the Should be triangular with apex at the cusp tip and base on the wax copingcusp tip and base on the wax coping

Should not modify the existing cusp Should not modify the existing cusp tiptip

No contact with the opposing tooth in No contact with the opposing tooth in centric and eccentric positionscentric and eccentric positions


Step 9: Mesiobuccal and Step 9: Mesiobuccal and Distobuccal cusp ridgesDistobuccal cusp ridges

Each has a slight convexity between the buccal Each has a slight convexity between the buccal crest of contour and the BO line.crest of contour and the BO line.

Do not modify the existing cusp tip or contact any Do not modify the existing cusp tip or contact any opposing tooth surface in any centric or eccentric opposing tooth surface in any centric or eccentric positionposition

Transition should be continuous with the remaining Transition should be continuous with the remaining wax pattern providing physiologic embrasureswax pattern providing physiologic embrasures

Inner aspects are convex surfaces that slope down Inner aspects are convex surfaces that slope down into the marginal ridges and form the buccal into the marginal ridges and form the buccal portion of the MB and DO Fossaportion of the MB and DO Fossa

Mesiobuccoocclusal and distobuccoocclusal point Mesiobuccoocclusal and distobuccoocclusal point angles should align buccolingually with the point angles should align buccolingually with the point angle of the adjacent teeth providing physiologic angle of the adjacent teeth providing physiologic occlusal embrasure.occlusal embrasure.


Step 10: Buccal Cusp Step 10: Buccal Cusp Triangular RidgesTriangular Ridges

Should be convex in all dimensions.Should be convex in all dimensions. Greater MD width at the central fossa line Greater MD width at the central fossa line

than the cusp tip line.than the cusp tip line. Supplemental grooves are developed to Supplemental grooves are developed to

separate the mesial and distal aspects of separate the mesial and distal aspects of the buccal cusp triangular ridges from the the buccal cusp triangular ridges from the respective inner aspects of the MB and DB respective inner aspects of the MB and DB cusp ridges.cusp ridges.

Do not contact the opposing teeth in any Do not contact the opposing teeth in any centric or eccentric position.centric or eccentric position.


Subtractive Subtractive TechniqueTechnique


Develop Axial Contours on the dies.Develop Axial Contours on the dies. Block out areas of the functional core that Block out areas of the functional core that

should not contact the wax.should not contact the wax. Lubricate the blocked out coreLubricate the blocked out core Warm the tip of a chip blowerWarm the tip of a chip blower Heat each occlusal surface separately with Heat each occlusal surface separately with

warm air stream from the chip blowerwarm air stream from the chip blower Close the lubricated functional core onto the Close the lubricated functional core onto the

soft occlusal wax and observe the wax soft occlusal wax and observe the wax patternpattern


Repeat the above procedure for each Repeat the above procedure for each wax pattern.wax pattern.

Close the functional core into all the Close the functional core into all the wax patterns at the same time, making wax patterns at the same time, making sure the guide pin touches the tablesure the guide pin touches the table

Coat the occlusal of the anatomic castCoat the occlusal of the anatomic cast Close the anatomic cast into the wax Close the anatomic cast into the wax

pattern making the contacts in white pattern making the contacts in white on the wax patternson the wax patterns

Carve anatomic contours into the Carve anatomic contours into the occlusal surface, taking care to avoid occlusal surface, taking care to avoid carving away the white occlusal carving away the white occlusal contactscontacts


Round the carved occlusal of the wax Round the carved occlusal of the wax pattern of the wax pattern with a gentle pattern of the wax pattern with a gentle warm air stream from a heated chip blowerwarm air stream from a heated chip blower

Close the functional into the warmed Close the functional into the warmed occlusal of the wax pattern.occlusal of the wax pattern.

Remove any excess wax and round any Remove any excess wax and round any flattened areas with a carving instrumentflattened areas with a carving instrument

Smooth the occlusal of the wax pattern Smooth the occlusal of the wax pattern with a gentle, warm air stream from a with a gentle, warm air stream from a heated chip blower and check the finished heated chip blower and check the finished wax pattern both the functional core and wax pattern both the functional core and the anatomic cast.the anatomic cast.


MARGIN FINISHINGMARGIN FINISHING The margin is critically important area of any wax The margin is critically important area of any wax

pattern. While a good margin may not insure the pattern. While a good margin may not insure the success of a casting, a poor one can almost success of a casting, a poor one can almost guarantee its failureguarantee its failure

Smooth any roughness on the axial surface with a Smooth any roughness on the axial surface with a slightly warm beavertail burnisher.slightly warm beavertail burnisher.

Any excess wax is carved almost to the margin Any excess wax is carved almost to the margin with a PKT no4.with a PKT no4.

Finish carving the margin with a slightly warm Finish carving the margin with a slightly warm beavertail burnisherbeavertail burnisher

Do not approach the finish line on the die with a Do not approach the finish line on the die with a sharp instrument as it can remove die material as sharp instrument as it can remove die material as well as the wax margins, resulting in a casting well as the wax margins, resulting in a casting that will not fit the prepared tooththat will not fit the prepared tooth


OVERWAXED MARGINS: areas in which OVERWAXED MARGINS: areas in which wax has been carried past the finish line wax has been carried past the finish line may break off when the pattern is may break off when the pattern is withdrawn from the die, resulting in a withdrawn from the die, resulting in a short or shy margin. If the overwaxes area short or shy margin. If the overwaxes area does not break off, it may spring back. does not break off, it may spring back. When cast in metal, this area will no When cast in metal, this area will no longer bend as it once did in wax, and the longer bend as it once did in wax, and the casting may be prevented from seating all casting may be prevented from seating all the way on the tooththe way on the tooth

SHORT MARGINS: will not provide an SHORT MARGINS: will not provide an adequate seal for the finished restorations adequate seal for the finished restorations


RIPPLES: any roughness in wax near the RIPPLES: any roughness in wax near the margin will be duplicated in the casting. If margin will be duplicated in the casting. If allowed to remain on the finished, allowed to remain on the finished, cemented restorations, these areas act as cemented restorations, these areas act as colecting point for plaque, leading to colecting point for plaque, leading to irritation and inflammation of the gingival irritation and inflammation of the gingival tissue.tissue.

THICK MARGINS: a thick, rounded margin THICK MARGINS: a thick, rounded margin will result in poor sealing of the restoration will result in poor sealing of the restoration and poor axial contours that will ultimately and poor axial contours that will ultimately lead to periodontal problems. The margins lead to periodontal problems. The margins must come to a knife edgemust come to a knife edge

OPEN MARGINS: attention to detail is OPEN MARGINS: attention to detail is essential to produce close margins. The essential to produce close margins. The pattern must be burnished and melted, as pattern must be burnished and melted, as well as cut, to ensure close adaptation of well as cut, to ensure close adaptation of the wax to the die in the marginal areasthe wax to the die in the marginal areas


To finish the occlusal grooves, hold a To finish the occlusal grooves, hold a very small cotton pellet in cotton very small cotton pellet in cotton pliers and dip it in the die lubricant. pliers and dip it in the die lubricant. Run the pellet carefully through the Run the pellet carefully through the groovesgrooves

Same method is employed to finish Same method is employed to finish the axial surfaces.the axial surfaces.

Avoid excessive or prolonged buffing Avoid excessive or prolonged buffing action near marginsaction near margins

Remove all lubricant from pattern Remove all lubricant from pattern once polishing is over. Any lubricant once polishing is over. Any lubricant left on the pattern when it is invested left on the pattern when it is invested can cause surface roughnesscan cause surface roughness


Depressions cannot be polished away. Depressions cannot be polished away. They are better removed by filling They are better removed by filling them with wax and then smoothening them with wax and then smoothening themthem

The purpose of finishing is to provide a The purpose of finishing is to provide a smooth surface for castingsmooth surface for casting

Wax is softer than metal. Anything Wax is softer than metal. Anything that can be done in wax, as opposed that can be done in wax, as opposed to doing it later in metal, should be. In to doing it later in metal, should be. In wax, anything can be done in a wax, anything can be done in a fraction of time, with less effort, and fraction of time, with less effort, and with better results.with better results.


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