WAX PATTERN

PRESENTER: Dr Manjima Khandelwal

PRECEPTOR: Dr Vishwas Bhatia

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CONTENTS

• Introduction
• Prerequisites
• Material Science
• Armamentarium
• Waxing Instruments
• Wax Added Technique
• Cusp to Marginal Ridge Waxing
• Cusp to Fossa Waxing
• Marginal Adaptation
• Review of Technique
• Video
• Functionally Generated Path Technique
• Wax Cut Back
• Problem Areas
• Conclusion
• References

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The fixed partial denture should resemble the natural dentition in form and function.

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Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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• A large percentage of time and effort spent in fabricating metal or pressed-ceramic fixed prostheses is devoted to producing a very accurate wax pattern.

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• From this pattern, the finished restoration is duplicated through the use of the lost-wax process as part of the indirect procedure.

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Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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PREREQUISITES�

The definitive die and cast may require small modifications before waxing is started.

• Correction of Defects
• Provision of Adequate Space for the Luting Agent
• Marking the Margins

Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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CORRECTION OF DEFECTS

• Even a very small undercut on the die of a tooth preparation makes wax pattern removal very difficult.

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• Such areas are normally blocked out intraorally with glass ionomer or restored with amalgam or another suitable material.

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• However, blocking them out on the working die may be more practical and convenient, as long as the defect does not extend to within 1 mm of the cavity margin.

Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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Provision of Adequate Space for the Luting Agent �

• Since the 1920s, practitioners have recognized that a space should exist between the internal surface of the casting and the prepared surface of the tooth everywhere except immediately adjacent to the margin.

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• The space provides room for the luting agent (a material that on hardening fills the space and binds the tooth and crown together) and allows complete seating of the restoration during cementation.

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• At the preparation margin, there should be a band of close adaptation (about 1 mm wide) to prevent disintegration and dissolution of the luting agent.

Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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The ideal dimension for the luting agent space has been suggested at 20 to 40 µm for each wall, which implies that a complete crown should have an internal diameter between 40 and 80 µm larger than the diameter of the prepared tooth.

Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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• If the luting agent space is too narrow, the restoration will not seat properly during cementation because of hydraulic pressure that develops when the viscous mass of luting agent cannot escape through the narrow gap between crown and preparation as the restoration is seated.

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• Conversely, if the luting agent space is too wide, the casting is loose on the tooth, resistance form is reduced, and the position of the crown is difficult to maintain accurately during evaluation and occlusal adjustment

Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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Increasing the Space for the Luting Agent:

A number of factors increase the space for the luting agent for a complete crown:

• Increased thermal and polymerization shrinkage of the impression material

• Use of an internal (initial) layer of soft wax in the wax pattern

• Use of die spacers

• Increased expansion of the investment mold

• Removal of metal from the fitting surface by grinding, airborne-particle abrasion, etching with aqua regia, or electrochemical milling

Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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Reduction of the Space for the Luting Agent:

A number of factors reduce the cement space:

• Reduced thermal and polymerization shrinkage of the impression material

• Use of alloys with a higher melting temperature range

• Reduced expansion of the investment

Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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Die Spacer

• This material is applied to the die to increase the cement space between axial walls of the prepared tooth and the restoration.
• It is formulated to maintain constant thickness when painted on the die.

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• However, it should not coat the entire preparation.
• For adequate marginal adaptation, a band of about 1 mm immediately adjacent to the preparation margin must be left unpainted.
• Use of thickened die spacer can result in an excessive thickness of spacer.

Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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Marking the Margins �

• The technician’s awareness of the precise location of the preparation margin is crucial.
• By marking it with the side of a colored pencil tip, the technician can pinpoint this location.
• The color should contrast with that of the wax that will be used.

Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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MATERIAL SCIENCE

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• Waxes are thermoplastic materials which are solids at room temperature but melt without decomposition to form mobile liquids.

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According to Anusavice:

• “A low molecular weight ester of fatty acids with monohydrate alcohol derived from natural and synthetic components such as petroleum derivatives that softens to a plastic state at a relatively low temperature.

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HISTORY:

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• First cast inlay is attributed to “philbrook”-1897

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• “Taggart” in 1907 introduced lost wax technique.

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Phillips’ Science of Dental Materials; Anusavice KJ; 12^th Ed; 194-200  

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The American National Standards Institute (ANSI) and the American Dental Association (ADA) categorized waxes into two types:

• 1. Type I: a medium-hardness wax (generally used with the direct technique for making patterns in the oral cavity)
• 2. Type II: a softer wax (generally used for the indirect fabrication of castings)

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• Waxes used with direct techniques must not flow appreciably at mouth temperature.
• Those used with indirect techniques must resist flow at room temperature to maintain their newly shaped forms.

Phillips’ Science of Dental Materials; Anusavice KJ; 12^th Ed; 194-200  

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Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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INLAY WAX

Blue, Green, Ivory or Deep Purple colours

Phillips’ Science of Dental Materials; Anusavice KJ; 12^th Ed; 194-200  

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• Waxes have highest CTE of any dental material; therefore care must be exercised to minimise distortion of pattern through extreme temperatures.
• Waxes are partly elastic and tend to return to their original shape after deformation.
• Elastic recovery is slower at lower temperature, so if the immediate investing of the pattern is not possible, then they should be stored in refrigerator.
• If the wax is refrigerated, it should be allowed to warm before investing.

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Softened or melted wax applied to die tends to adhere.

Phillips’ Science of Dental Materials; Anusavice KJ; 12^th Ed; 194-200  

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Manipulation

Phillips’ Science of Dental Materials; Anusavice KJ; 12^th Ed; 194-200  

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INDIRECT METHOD OF MANIPLUATION

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• Dipping Method
• Softening wax in warm water
• Adding in layers

Phillips’ Science of Dental Materials; Anusavice KJ; 12^th Ed; 194-200 

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TYPES OF INLAY WAXES

• Occlusal Waxes
• Milling Waxes
• Cervical Waxes
• Underlining Waxes
• Crown Waxes
• Waxes for all-ceramic
• Block out waxes
• Stick-on Waxes
• Occlusal Powder

Phillips’ Science of Dental Materials; Anusavice KJ; 12^th Ed; 194-200  

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OCCLUSAL WAXES

• Ideal for effective and aesthetic modelling of chewing surfaces.
• High degree of hardness
• More tolerant for jaw movements.
• Setting temperature around 59°C

Phillips’ Science of Dental Materials; Anusavice KJ; 12^th Ed; 194-200  

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MILLING WAXES:

• Optimised composition for processing with milling tools.
• Wax-up surfaces are made very smooth, with sharp contours.
• Setting temperature is approx. 62°C

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CERVICAL WAX:

• For details on cervical edges of crowns, precision parts and

inlays.

• Wax can be modelled reliably and extremely thin as far as the

preparation limits.

• Very slight shrinkage
• Setting time approx. 62°C

Phillips’ Science of Dental Materials; Anusavice KJ; 12^th Ed; 194-200  

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UNDERLYING WAXES:

• As first layer of wax-up for inlays and crowns.
• Stable and has exact fitting
• Opaque for better contrast to the dies
• High density enables carving

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CROWN WAX:

• Hard and medium hard waxes in colours blue and dark blue.
• Setting temperature for hard is approx. 61 ° C and for medium-hard is approx. 62°C

Phillips’ Science of Dental Materials; Anusavice KJ; 12^th Ed; 194-200  

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WAX FOR ALL-CERAMIC:

• They are filtered several times and are free from any opaque particles, which could possibly react with the embedding materials or casted objects.

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BLOCK-OUT WAX:

• Not suitable for casting techniques as they do not burn without residue.
• Blocks out undercuts or to smooth rough surfaces on dies.
• Adapts easily to the contours of the die.
• Easy to remove at the end of process.

Phillips’ Science of Dental Materials; Anusavice KJ; 12^th Ed; 194-200  

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STICK-ON WAX:

• To place casting channels, sprues and pontics.
• Perfectly sticks, easy correction of position.
• Stays smooth and sticky
• Burns without residue.

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OCCLUSAL POWDER:

• Consists of 100% wax
• Easy to apply with brush
• Serves as a separating powder when applying hot wax.
• Burns without residue.

Phillips’ Science of Dental Materials; Anusavice KJ; 12^th Ed; 194-200  

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WAX PATTERN FABRICATION

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ARMAMENTARIUM

The following equipment are needed:

• Bunsen burner

• Inlay wax

• Waxing instruments

• Cotton cleaning cloth

• Sharp colored pencil

• Separating liquid

• Soft toothbrush

• Double-sided brushes (soft/rigid)

• Occlusal indicator powder: zinc stearate or powdered wax

• Cotton balls

• Fine nylon hose

Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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WAXING INSTRUMENTS

• Designed by Peter K Thomas
• For wax additive waxing technique

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• No 1 and No 2: Wax addition instruments
• No 3: Burnisher for refining occlusal anatomy
• No 4 and No 5: Wax carvers

Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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FUNCTIONAL OCCLUSAL WAX-UP �or�THE WAX-ADDED TECHNIQUE

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• To apply the principles of articulation when waxing the occlusal surface or opposing occlusal surface of the posterior teeth, the wax-added technique or the functional occlusal technique was developed.

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• Its advantage over carving technique is that it provides an organized step-to-step procedure to develop the occlusal anatomic form.

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Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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A: Margins of coping was are removed.

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B: Coping on the die with wax on the margins removed.

Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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A: Margin wax is added using a dropper.

B: Finished coping removed from the die and margins are verified.

Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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CUSP - TO - MARGINAL RIDGE WAXING

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Step 1: Build-Up of Cones

Build-up cones for maxillary 1^st premolar

Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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Note:

• The lingual cusp of maxillary first premolar is located slightly anterior to the buccal cusp.
• On maxillary molars, the mesio-lingual cusp appears to be framed between the mesio-buccal and disto-buccal cusp when viewed buccally.

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But:

• These are arbitrary considerations.
• The opposing occlusion and its dynamic function will influence modification to cusp height and placement.

A: Maxillary right 1^st premolar

B: Maxillary right 1^st molar

Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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Build-up cones for mandibular molar

Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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Step 2: Adding the Triangular Ridges

• The linguo triangular ridge should contact the distal cuspal ridge of the opposing premolar, but disclude during any excursive movement.

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• Similarly, buccal triangular ridge is formed.

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• There should be no interreference when the articulator is moved in eccentric excursions.

Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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Addition of triangular ridges on mandibular molar

Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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Step 3: Adding Axial contour ridges

• Buccal and lingual contour ridges are completed to complete the axial tooth form.

Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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Step 4: Adding mesial and distal cuspal ridges

• They complete the buccal and lingual outline form of the tooth.
• There should be no contact in eccentric excursions except when working group function is indicated.

Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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Step 5: Adding the marginal ridges

• The mesial and distal marginal ridges complete the occlusal outline form of the tooth and forms interproximal embrasures.
• As the articulator is closed, the opposing cusp will determine the height of marginal ridge.

Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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Step 6: Fill-in and Refinement

The supplemental anatomy and refinement of the final occlusal form is now completed.

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No. 23 sickle explorer is used to add minute details.

Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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Fundamentals Of Fixed Prosthodontics- Shillingburg et al; 4^rd Edition; 343-361

Cones for facial cusp. PKT-1

Facial ridges and triangular ridges. PKT-1

Mesial and distal cusp ridges for facial cusp. PKT-1

Cones for palatal cusp. PKT-1

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Fundamentals Of Fixed Prosthodontics- Shillingburg et al; 4^rd Edition; 343-361

Mesial and distal cusp ridges for palatal cusp. PKT-1

Facial ridges and triangular ridges. PKT-1

Marginal ridges. PKT-1

Supplemental anatomy. PKT- 3 and 5

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CUSP-TO-FOSSA WAXING

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• Also called Cups-to-embrasure waxing
• Coined by Lundeen in 1969

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It is so widely accepted because, biomechanically

• The most stable tooth contact in the position of maximal intercuspation can be established
• The occlusal forces can be most axially directed, and
• The ‘wedging effect’ of a cusp articulated over the occlusal embrasure is avoided (Thomas, 1967)

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Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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• In appearance, the restoration cannot and need not to be an exact reproduction of the natural tooth.
• The restoration should just be a expression of the functional principles of tooth morphology.

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• It is the skeletal relationship of the teeth that can cause a variety of combinations of cup-to-fossa contacts.

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Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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The biomechanical principle:

• The stamp cusp should articulate with within a fossa of an opposing tooth
• With this contact the occlusal forces are transmitted to the supporting tissues in the most axial direction.

Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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Fundamentals Of Fixed Prosthodontics- Shillingburg et al; 4^rd Edition; 343-361

Cones for facial cusp. PKT-1

Cones for lingual cusp. PKT-1

Marginal ridges and cusp ridges. PKT-1

Smoothening axial contours. PKT-1

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Fundamentals Of Fixed Prosthodontics- Shillingburg et al; 4^rd Edition; 343-361

Triangular ridges. PKT-1

Supplemental anatomy. PKT- 3 and 5

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MARGIN ADAPTATION OF WAX PATTERN

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Margin is re-melted with PKT-1 instrument

A depression remains near the margins

Fundamentals Of Fixed Prosthodontics- Shillingburg et al; 4^rd Edition; 343-361

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Wax is added at the margins

Excess wax is removed with PKT-4

Fundamentals Of Fixed Prosthodontics- Shillingburg et al; 4^rd Edition; 343-361

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Margins are finished

Finished margin is viewed from an apical direction

Fundamentals Of Fixed Prosthodontics- Shillingburg et al; 4^rd Edition; 343-361

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Grooves are finished and smoothened with cotton pellet

Axial surfaces are smoothened with cotton

Fundamentals Of Fixed Prosthodontics- Shillingburg et al; 4^rd Edition; 343-361

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• The margin is a critically important area of any wax pattern.
• While a good margin may not ensure the success of a casting, but a poor one can almost guarantee its failure.

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Margins should be checked for :

• Short Margins
• Ripples
• Thick Margins
• Thin Margins
• Open Margins

Fundamentals Of Fixed Prosthodontics- Shillingburg et al; 4^rd Edition; 343-361

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REVIEW OF TECHNIQUE

• The die is modified as necessary and lubricated
• An initial coping is waxed; this forms the internal surface.
• The proximal surfaces are developed, with correctly located contact areas The axial surfaces are waxed.
• Over-contouring near the gingival margin must be avoided.
• The occlusal surfaces are developed with a wax addition technique, which makes it easier to determine the best location of cusps and occlusal contacts
• The margins are reflowed, and the wax pattern is finished

Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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FUNCTIONALLY GENERATED PATH TECHNIQUE

• It is an alternative way of forming the occlusal surface of a wax pattern.

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• This method was first described by Meyers in 1933.

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• Rather than employing an articulator to stimulate the movement of the mandible, this technique uses a tracing made in the mouth to capture the path travelled by opposing cusp in mandibular function.

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Fundamentals Of Fixed Prosthodontics- Shillingburg et al; 4^rd Edition; 343-361

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DuVall N; Rogers P; Application of the Functionally Generated Path Technique to Restore Mandibular Molars in Bilateral Group Function Occlusion; J Prosthodont; 2013; Apr; 22; 3; 226-32

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WAX CUT BACK

If a ceramic veneer is to be used, once the definitive contour of the wax pattern has been completed, the pattern is cut back over an even thickness usually approx 1 mm to provide room for the porcelain fused onto the cast metal substructure

Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530

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PROBLEM AREAS

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Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212

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CONCLUSION

• Crown /FDP should resemble natural dentition in form and function.
• Determinants of occlusion and their effect on the occlusal surface of teeth.
• Able to interpret harmonious relationship with adjacent teeth and soft tissues.
• The wax pattern should be a precise model for the final restoration.
• During fabrication of wax patterns, the design principles for optimal biomechanical and hygienic function should be considered.
• If the waxing procedure is followed in a sequential order, operators should have no problem achieving excellent results.

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REFERENCES

• Contemporary Fixed Prosthodontics- Rosenstiel , Land And Fujimoto. 5^th Ed; 499-530
• Fundamentals Of Fixed Prosthodontics- Shillingburg et al; 4^rd Edition; 343-361
• Dental Laboratory Procedures- Fixed Partial Dentures; Rhoads, Rudd, Morrow; 2^nd Ed; 170-212
• Phillips’ Science of Dental Materials; Anusavice KJ; 12^th Ed; 194-200
• Restorative Dental Materials; Robert G. Craig; 11^th Ed; 339-356 
• Wheeler’s Dental Anatomy, Physiology and Occlusion; Nelson, Ash; 9^th Ed
• Council on Dental Materials, Instruments, and Equipment: Revised ANSI/ADA specification No. 4 for inlay wax; J Am Dent Assoc; 1984; 88; 108-125
• Lundeen HC; Introduction to Occlusal Anatomy; J Prosthet Dent; 1969
• Thomas PK; Syllabus on Full Mouth Waxing Technique for Rehabilitation; 1967

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THANK YOU

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