INLAY CASTING WAX

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INLAY CASTING WAX
Dental Materials Lecture BDS II Year
Dr. Raghuwar D Singh Associate Professor
Prosthodontic Department King Georges Medical
University UP, Lucknow
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• First procedure in the casting of an inlay or
  crown is the preparation of a wax pattern.
• TECHNIQUES for WAX PATTERN Preparation
• Direct Technique
• Indirect Technique

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• TYPES OF INLAY CASTING WAX --
• According to ADA Specification No. 4
• TYPE I Medium Wax for Direct Technique
• TYPE II Soft Wax for Indirect Technique

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COMPOSITION

• Paraffin wax 40 to 60
• Gum dammar
• Carnauba wax
• Coloring agent

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• PARAFFIN WAX
• Derived from high boiling fraction of
  petroleum.
• Depending upon Molecular Wt. Distribution
  can be obtained in a wide melting or softening
  range.
• Paraffin used for Type I waxes have higher
  melting point than the Paraffin used for Type II
  waxes.

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• DISADVANTAGES
• Flake when it is trimmed.
• Does not present Smooth, Glossy surface.

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• GUM DAMMAR or DAMMAR RESIN
• Natural Resin.
• Added to improve the smoothness in molding.
• Resistant to Cracking Flaking.
• Increases the Toughness of the wax.
• Enhances the Smoothness of the surface.

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• CARNAUBA WAX
• Occurs as fine powder.
• Quite Hard in nature.
• High Melting point.
• Combined with paraffin to Decrease the flow
• at mouth temperature.
• Give more Glossiness to wax surface than
• dammar resin.

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• CANDELILLA WAX can also be added to replace
  the Carnauba wax.
• Its Melting point is lower.
• Not as hard as Carnauba wax.
• CERESIN may replace part of Paraffin to modify
• the toughness carving characteristics of
  wax.

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• In modern Inlay Waxes, the Carnauba Wax is
• often replaced in part with certain Synthetic
  
• Waxes that are compatible with Paraffin wax.
• Two waxes of this Types are
• Complex Nitrogen derivatives of higher fatty
• acids.
• Esters of acids derived from Montan wax.

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PROPERTIES OF INLAY WAX

• When softened wax should be uniform.
• Color should contrast with the die material.
• No Flakiness or similar surface roughness when
  wax is bent molded after softening.

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• Should Vaporize completely during burnout
• (5000c).
• Wax should not pull or chip during carving.
• Wax pattern should be completely rigid
• dimensionally stable.

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• FLOW
• THERMAL PROPERTIES
• WAX DISTORTION
• MANIPULATION OF INLAY WAX
• OTHER DENTAL WAXES

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• FLOW
• Requirements according to ADA Specification no.
  4,
• At 450C -- Both Type I II should have a flow
  b/w
• 70 to 90 .
• At 370C -- Type I should not flow more than 1
  .
• At 300C -- Type II should not flow more than 1
  .

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• THERMAL PROPERTIES
• THERMAL CONDUCTIVITY
• Low.
• Takes time to heat the wax uniformly.

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• COEFFICIENT OF THERMAL EXPANSION
• High.
• Thermal changes are higher than any other
  materials.
• Linear expansion of 0.6 when heated from 25
• to 370C is permitted for Type I waxes.
• This property is more significant in Direct Tech.

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• Other Factors that influence the Coefficient
  of
• Thermal Expansion are
• Temperature of the Die.
• Method used for applying pressure to the wax.

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• WAX DISTORTION
• Most serous problem in Inlay wax.
• It is due to Release of Stresses in pattern due
  to,,
• Contraction on cooling.
• Occluded gas bubbles.
• Change of shape of wax during moulding.
• From Manipulation, Carving, Pooling
• Removal.

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• CAUSES OF DISTORTION
• If wax is not at uniform temp. when inserted in
  the cavity.
• If wax is not help under uniform pressure during
  cooling.
• If wax is added in an area of deficiency.

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• TO AVOID DISTORTION OF WAXES
• Minimal carving change in temperature.
• Minimal Storage of pattern.
• Use warm instrument for carving.
• Store it in a Fridge if necessary.

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MANIPULATION OF INLAY WAX

• TECHNIQUES
• DIRECT TECHNIQUE
• INDIRECT TECHNIQUE

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• DIRECT TECHNIQUE
• Softened the stick of wax over the flame.
• Inserted into the cavity held under finger
• pressure.
• Allow to cool gradually at mouth temperature.
• Withdraw the wax pattern carefully.

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• INDIRECT TECHNIQUE
• Pattern is prepared over a lubricated die.
• If molten wax used, very little stresses occur.

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• METHODS OF INDIRECT TECHNIQUE
• Dipping Method
• In full crowns.
• Die is dipped in hot liquid wax.
• Softening In Warm Water Not recommended.
• Adding in Layer Using spatula or brush.

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OTHER DENTAL WAXES
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• RPD WAXES
• PRECESSING WAXES
• Boxing Beading Waxes.
• Utility Wax.
• Sticky Wax.
• IMPRESSION WAXES
• Corrective impression Wax
• Bite Registration Wax

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RPD WAXES

• USES
• To make patterns of metallic framework of RPD.
• Pattern for RPD is made on a special cast known
  as the Refractory Cast.

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• SUPPLIED AS --
• Sheets .40 and .32 mm thickness.
• Readymade shapes, Round, Half round
• Grid
  or Meshform
• Clasp
  shapes
• Other
  forms.
• Bulk.

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• PROPERTIES
• Highly Ductile, as they must adapt easily and
• stick onto the refractory cast.
• Must Vaporize during burnout.

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BASEPLATE WAXorMODELING WAX
Supplied as, Sheets of pink or red colour.
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• USES
• To make Occlusion rim.
• To form the desired contour of denture after
• teeth are set.
• To make patterns for Orthodontic appliances.

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• CLASSIFICATION
• Type I Soft for building
  Veneers.
• Type II Medium
• Type III Hard

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• COMPOSITION
• Paraffin wax or Ceresin 80
• Beeswax 12
• Carnauba wax 2.5
• Natural or Synthetic resin 3
• Microcrystalline 2.5

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PROCESSING WAX

• Used mainly as accessory aids.

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• Examples are ,
• Boxing Wax Beading Wax.
• Utility Wax.
• Sticky Wax.

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BOXING BEADING WAX

• USES --
• To build up vertical walls around the
  impression.
• SUPPLIED AS
• Boxing wax as sheets.
• Beading wax as strips.

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UTILITY WAX

• Supplied as Sticks and Sheets.
• Uses To adjust the contour of perforated
  tray.
• Composition Petrolatum other waxes.
• It is adhesive and can stick to the
  tray.

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STICKY WAX

• USES --
• To join metal parts before soldering.
• To join fragments of broken dentures before
• repair.

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• COMPOSITION --
• Mainly Yellow Beeswax, Rosin Natural
  resins such as Gum dammer.
• PROPERTIES
• Sticky when melted Adheres closely to surface.
• Firm and Brittle at room temperature.

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IMPRESSION WAXES

• Used to record non undercut edentulous portions
  of the mouth.
• Examples are ,
• CORRECTIVE IMPRESSION WAX
• BITE REGISTRATION WAX

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CORRECTIVE IMPRESSION WAX

• USES --
• To make functional impression of RPD.
• To record Posterior Palatal Seal.
• Functional Impression for Obturatures.

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• COMPOSITION --
• Paraffin wax
• Ceresin wax
• Beeswax
• May contain metal particles.
• PROPERTIES
• FLOW at 37 0 C is 100 .
• Should be poured immediately.

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BITE REGISTRATION WAX

• USES --
• To record the relationship between the upper
  and
• lower teeth.
• SUPPLIED AS -- U shaped rods.
• COMPOSITION -- Beeswax, Paraffin, Ceresin.

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MCQs

• 1. The role of gum dammar in Inlay casting wax
  is
• a) To improve cracking resistance
• b) To provide strength to wax
• c) To impact smoothness to pattern
• d) All of the above

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• 2. Carnauba was is preffered to candelila wax as
• It is harder and has less flow
• It has low melting temperature
• It provides luster to the pattern
• All of the above

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• 3. Inlay wax should have following requisites
• Its colour should be in contrast with tooth or
  die material
• It should have capability to be carved according
  to tooth anatomy and there should be no flaking.
• When heated, it should be completely eliminated
  from the mould.
• All of the above.

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• 4. Which of the following waxes is used for
  making of casting pattern
• Boxing wax
• Inlay wax
• Modeling wax
• Utility wax

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• 5. The minimum flow of inlay wax at 450C should
  be
• 60
• 6
• 70
• 100

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• 6. Which of the following correctly describe type
  I inlay casting wax
• Soft wax used for direct technique
• Medium wax used for indirect technique
• Soft wax used for indirect technique
• Medium was used for direct technique

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• 7. The maximum ingredient of inlay casting wax
• Paraffin wax
• Ceresin
• Carnauba wax
• Gum dammar

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• 8. Which of the following is added inlay casting
  was to improve the smoothness
• Ceresin
• Candellila wax
• Gum dammar
• Synthetic wax

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• 9. Percentage of Carnauba wax in inlay casting
  wax is
• 40
• 60
• 25
• 10

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• 10. Inlay casting wax is supplied as
• Sheets only
• Mesh form only
• Both of the above
• None of the above