WAX PATTERN FABRICATION FOR FPD

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WAX PATTERN FABRICATION FOR FPD
dr shabeel pn
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INTRODUCTION

• USUALLY WAX PATTERN FABRICATION DENOTES THE
  WAX PATTERN FABRICATED TO CAST METAL OR CASTABLE
  GLASS CERAMICS (DICOR). WAX PATTERN FABRICATION
  INVOLVES THREE MAJOR STEPS NAMELY FABRICATION OF
  THE RETAINER,THE PONTIC AND CONNECTOR

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FABRICATION OF THE RETAINER WAX PATTERN

• THE METHOD OF FABRICATION OF THE RETAINER
  COMPONENT WILL VARY ACCORDING TO THE MATERIAL
  USED AND THE DESIGN OF THE RESTORATION

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• DIRECT TECHNIQUE
• WAX PATTERN IS FABRICATED DIRECTLY OVER THE
  PREPARED TOOTH IN THE ORAL CAVITY
• DONE WITH TYPE-I WAX,HENCE NOT USED FOR FIXED
  PARTIAL DENTURE PATTERN

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• 2. INDIRECT TECHNIQUE
• PATTERN IS FABRICATED OVER THE PREPAIRED TOOTH IN
  THE DIE OR CAST
• MADE USING TYPE-II WAX
• ADVANTAGES
• DONE IN THE LAB THEREBY REDUCING THE CHAIRSIDE
  TIME
• DONE BY TECHNICIAN THEREBY REDUCING WORK LOAD OF
  DENTIST
• ALLOWS BETTER VISUALISATION OF THE MARGINS OF THE
  RESTORATION ESPECIALLY FROM THE GINGIVAL ASPECT

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PROCEDURE

• FABRICATED BY PREPARING A WAX COPING FOLLOWED BY
  ADDING LAYERS OF WAX TO BUILD UP AXIAL AND
  OCCLUSAL CONTOUR

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COPING PREPARATION

• PROCEDURE
• SURFACE CONTOURING AND MARGINAL FINISH ARE
  NECESSARY FOR ALL METAL OR DICOR CERAMIC RETAINER
• IN METAL CERAMIC RETAINER COPING IS ALONE
  PREPARED AND CASTED USING METAL CERAMIC ALLOY
• THE COTOURS AND MARGINS ARE DIERECTLY PREPARED
  USING CERAMIC AND FIRED

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COPING PREPARATION

• DONE USING WAX OR HEATED SHEET OF RESIN
• WAX COATED ON THE TOOTH USING A WAX SPATULA OR BY
  DIPPING THE DIE INTO THE HOT WAX

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• WHILE ADDING NEW LAYERS OF WAX THE PREVIOUS LAYER
  SHOULD BE MELTED TO AVOID FORMATION OF VOIDS
• COPING SHOULD BE WAXED IN EXCESS MESIALLO
  DISTALLY TO PRESERVE PROXIMAL CONTACT

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PREPARING THE AXIAL CONTOURS

• ESTABLISHING THE PROXIMAL CONTACT
• USUALY THE PROXIMAL CONTACT OCCUR AT HE OCCLUSAL
  THIRD WHEN VIEWED FROM SIDE
• PROXIMAL CONTACT SHOULD BE FACIALLY LOCATED WHEN
  VIEWED OCCLUSALLY

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• CONTACT AREA SHOULD BE OPTIMUM
• 
  

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• AXIAL SURFACE BELOW THE CONTACT SHOULD NEVER BE
  CONVEX
• LINGUAL PROMINENCE IS GREATER FOR MANDIBULAR
  POSTERIORS THAN MAXILLARY POSTERIORS

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• HEIGHT OF CONTOUR ON THE LINGUAL SURFACE
  MAXILLARY POSTERIORS OCCUR IN CERVICAL THIRD AND
  THE SAME IN MANDIBULAR POSTERIORS OCCUR IN MIDDLE
  THIRD

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PREPARING THE OCCLUSAL CONTOUR OR DEVELOPING
OCCLUSAL MORPHOLOGY

• IT SHOULD BE IN HARMONY WITH ADJUSENT OR OPPOSITE
  TEETH
• P.K. THOMAS CARVERS ARE USED TO CARVE THE OCLUSAL
  SURFACE
• PROCEDURE
• TAIL END OF PKT CARVER SHOULD BE USED TO BUILT
  CONES OF WAX OVER THE AREAS WHERE THE CUSPS ARE
  TO BE FORMED

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• MARGINAL RIDGES AND CUSP RIDGES ARE BUILT USING
  SAME INSTRUMENT
• PARTIALY WAXED OCCLUSAL SURFACE IS OCCLUDED
  AGAINST THE OPPOSING CAST

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• INTERNAL INCLINES OF THE CUSP ARE CONTORED
• RIDGES SHOULD BE CONVEX
• OCCLUSAL MORPHOLOGY SHOULD BE MODIFIED ACCORDING
  TO SURROUNDING TEETH

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FINISHING THE MARGINS OF THE PATTERN

• MARGINS ARE FINISHED TO A FINE EDGE USING
  BURNISHER
• A COTTON PELLET SOAKED IN DIE LUBRICANT IS USED
  TO FINISH THE OCCLUSAL GROOVES

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• THE AXIAL SURFACE IS FINISHED WITH A COTTON ROLL
  DIPPED IN A DIE LUBRICANT
• REMOVE THE LUBRICANT AFTER FINISHING

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PONTIC FABRICATION

• FABRICATION OF WAX PATTERN FOR METAL CERAMIC AND
  RESIN VENEERED PONTICS
• PROCEDURE
• AXIAL SURFACES ARE CONTOURED AS DESCRIBED FOR A
  RETAINER
• INLAY WAX IS SOFTENED AND FUSED TOOTH RETAINER IN
  THE FORM OF A CYLINDER

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• WAX CONE SHOULD BE PLACED ON THE FLAT OCCLUSAL
  SURFACE INORDER TO CONTOUR THE OCCLUSAL SURFACE
• THE RETAINER PATTERNS ARE FINISHED AND THE
  PROXIMAL AND THE GINGIVAL SURFACE OF THE PONTIC
  ARE CONTOURED ACCORDING TO THE NEIGHBOURING TEETH

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• GINGIVAL SURFACE IS CONTOURED ACCORDING TO DESIGN
  OF THE PONTIC

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