Dr. Raghuwar D SinghAssociate Professor

Prosthodontic DepartmentKing George’s Medical University UP, Lucknow

Dental Materials Lecture

BDS II Year

First procedure in the casting of an inlay or First procedure in the casting of an inlay or crown is the preparation of a wax pattern.crown is the preparation of a wax pattern.

TECHNIQUES for WAX PATTERN TECHNIQUES for WAX PATTERN Preparation::Preparation::

** Direct Technique Direct Technique

** Indirect Technique Indirect Technique

TYPES OF INLAY CASTING WAX --TYPES OF INLAY CASTING WAX --

** According to ADA Specification No. 4 ::According to ADA Specification No. 4 ::

TYPE I = Medium Wax for Direct TechniqueTYPE I = Medium Wax for Direct Technique

TYPE II = Soft Wax for Indirect Technique TYPE II = Soft Wax for Indirect Technique

COMPOSITIONCOMPOSITION

Paraffin wax = 40 to 60 %Paraffin wax = 40 to 60 % Gum dammar Gum dammar Carnauba waxCarnauba wax Coloring agent Coloring agent

PARAFFIN WAX : PARAFFIN WAX :

** Derived from high boiling fraction of petroleum.Derived from high boiling fraction of petroleum.

** Depending upon Molecular Wt. & Distribution Depending upon Molecular Wt. & Distribution can be obtained in a wide melting or softening can be obtained in a wide melting or softening range.range.

** Paraffin used for Type I waxes have higher Paraffin used for Type I waxes have higher melting point than the Paraffin used for Type II melting point than the Paraffin used for Type II waxes.waxes.

DISADVANTAGES –DISADVANTAGES –

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

GUM DAMMAR or DAMMAR RESIN :GUM DAMMAR or DAMMAR RESIN :

Natural Resin.Natural Resin.

Added to improve the smoothness in molding.Added to improve the smoothness in molding. Resistant to Cracking & Flaking.Resistant to Cracking & Flaking. Increases the Toughness of the wax.Increases the Toughness of the wax. Enhances the Smoothness of the surface.Enhances the Smoothness of the surface.

CARNAUBA WAX :CARNAUBA WAX :

Occurs as fine powder.Occurs as fine powder. Quite Hard in nature.Quite Hard in nature. High Melting point.High Melting point. Combined with paraffin to Decrease the flow Combined with paraffin to Decrease the flow

at mouth temperature.at mouth temperature. Give more Glossiness to wax surface than Give more Glossiness to wax surface than

dammar resin.dammar resin.

CANDELILLA WAX CANDELILLA WAX can also be added to can also be added to replace the Carnauba wax. replace the Carnauba wax.

Its Melting point is lower.Its Melting point is lower. Not as hard as Carnauba wax.Not as hard as Carnauba wax.

CERESINCERESIN may replace part of Paraffin to modify may replace part of Paraffin to modify

the toughness & carving characteristics of wax. the toughness & carving characteristics of wax.

In modern Inlay Waxes, the Carnauba Wax is In modern Inlay Waxes, the Carnauba Wax is

often replaced in part with certain Synthetic often replaced in part with certain Synthetic

Waxes that are compatible with Paraffin wax.Waxes that are compatible with Paraffin wax.

Two waxes of this Types are ::Two waxes of this Types are :: Complex Nitrogen derivatives of higher fatty Complex Nitrogen derivatives of higher fatty

acids.acids. Esters of acids derived from Montan wax.Esters of acids derived from Montan wax.

PROPERTIES OF INLAY WAXPROPERTIES OF INLAY WAX

When softened wax should be uniform.When softened wax should be uniform.

Color should contrast with the die material.Color should contrast with the die material.

No Flakiness or similar surface roughness No Flakiness or similar surface roughness when wax is bent & molded after softening.when wax is bent & molded after softening.

Should Vaporize completely during burnout Should Vaporize completely during burnout

(500(50000c).c).

Wax should not pull or chip during carving.Wax should not pull or chip during carving.

Wax pattern should be completely rigid & Wax pattern should be completely rigid &

dimensionally stable.dimensionally stable.

FLOWFLOW

THERMAL PROPERTIESTHERMAL PROPERTIES

WAX DISTORTIONWAX DISTORTION

MANIPULATION OF INLAY WAXMANIPULATION OF INLAY WAX

OTHER DENTAL WAXESOTHER DENTAL WAXES

FLOWFLOW – –

Requirements according to ADA Specification no. 4,Requirements according to ADA Specification no. 4,

At 45At 4500C -- Both Type I & II should have a flow b/w C -- Both Type I & II should have a flow b/w

70 to 90 %.70 to 90 %.

At 37At 3700C -- Type I should not flow more than 1 %.C -- Type I should not flow more than 1 %.

At 30At 3000C -- Type II should not flow more than 1 %.C -- Type II should not flow more than 1 %.

THERMAL PROPERTIESTHERMAL PROPERTIES – –

THERMAL CONDUCTIVITYTHERMAL CONDUCTIVITY : : Low. Low. Takes time to heat the wax uniformly.Takes time to heat the wax uniformly.

COEFFICIENT OF THERMAL EXPANSION COEFFICIENT OF THERMAL EXPANSION :: High.High.

Thermal changes are higher than any other Thermal changes are higher than any other materials.materials.

Linear expansion of 0.6 % when heated from 25Linear expansion of 0.6 % when heated from 25

to 37to 3700C is permitted for Type I waxes.C is permitted for Type I waxes.

This property is more significant in Direct Tech.This property is more significant in Direct Tech.

** Other Factors that influence the Coefficient of Other Factors that influence the Coefficient of

Thermal Expansion are –Thermal Expansion are –

Temperature of the Die.Temperature of the Die. Method used for applying pressure to the wax.Method used for applying pressure to the wax.

WAX DISTORTION –WAX DISTORTION – Most serous problem in Inlay wax.Most serous problem in Inlay wax.

It is due to Release of Stresses in pattern due to,,It is due to Release of Stresses in pattern due to,,

* Contraction on cooling.* Contraction on cooling.

* Occluded gas bubbles.* Occluded gas bubbles.

* Change of shape of wax during moulding.* Change of shape of wax during moulding.

* From Manipulation, Carving, Pooling & * From Manipulation, Carving, Pooling &

Removal.Removal.

CAUSES OF DISTORTIONCAUSES OF DISTORTION : :

If wax is not at uniform temp. when inserted in the If wax is not at uniform temp. when inserted in the cavity.cavity.

If wax is not help under uniform pressure during If wax is not help under uniform pressure during cooling.cooling.

If wax is added in an area of deficiency.If wax is added in an area of deficiency.

TO AVOID DISTORTION OF WAXES :TO AVOID DISTORTION OF WAXES :

Minimal carving & change in temperature.Minimal carving & change in temperature.

Minimal Storage of pattern.Minimal Storage of pattern.

Use warm instrument for carving.Use warm instrument for carving.

Store it in a Fridge if necessary.Store it in a Fridge if necessary.

MANIPULATION OF MANIPULATION OF INLAY WAXINLAY WAX

TECHNIQUES –TECHNIQUES –

DIRECT TECHNIQUEDIRECT TECHNIQUE

INDIRECT TECHNIQUEINDIRECT TECHNIQUE

DIRECT TECHNIQUE ::DIRECT TECHNIQUE ::

Softened the stick of wax over the flame.Softened the stick of wax over the flame.

Inserted into the cavity & held under finger Inserted into the cavity & held under finger

pressure.pressure.

Allow to cool gradually at mouth temperature.Allow to cool gradually at mouth temperature.

Withdraw the wax pattern carefully.Withdraw the wax pattern carefully.

INDIRECT TECHNIQUE ::INDIRECT TECHNIQUE ::

Pattern is prepared over a lubricated die.Pattern is prepared over a lubricated die.

If molten wax used, very little stresses occur.If molten wax used, very little stresses occur.

METHODS OF INDIRECT TECHNIQUE –METHODS OF INDIRECT TECHNIQUE –

Dipping Method – Dipping Method – * In full crowns.* In full crowns. * Die is dipped in hot liquid wax.* Die is dipped in hot liquid wax.

Softening In Warm Water – Softening In Warm Water – Not recommended.Not recommended. Adding in Layer – Adding in Layer – Using spatula orUsing spatula or brush.brush.

OTHER DENTAL WAXESOTHER DENTAL WAXES

RPD WAXESRPD WAXES

PRECESSING WAXESPRECESSING WAXES

* Boxing & Beading Waxes.* Boxing & Beading Waxes.

* Utility Wax.* Utility Wax.

* Sticky Wax.* Sticky Wax.

IMPRESSION WAXESIMPRESSION WAXES

* Corrective impression Wax* Corrective impression Wax

* Bite Registration Wax* Bite Registration Wax

RPD WAXESRPD WAXES

USES –USES –

To make patterns of metallic framework of RPD.To make patterns of metallic framework of RPD.

Pattern for RPD is made on a special cast known as the Pattern for RPD is made on a special cast known as the Refractory Refractory CastCast..

SUPPLIED AS --SUPPLIED AS --

** Sheets Sheets .40 and .32 mm thickness. .40 and .32 mm thickness.

** Readymade shapesReadymade shapes, Round, Half round, Round, Half round

Grid or MeshformGrid or Meshform

Clasp shapesClasp shapes

Other forms.Other forms.

** Bulk.Bulk.

PROPERTIES –PROPERTIES –

Highly Highly DuctileDuctile, as they must adapt easily and, as they must adapt easily and

stick onto the refractory cast.stick onto the refractory cast.

Must Must VaporizeVaporize during burnout. during burnout.

BASEPLATE WAXBASEPLATE WAXoror

MODELING WAXMODELING WAX

Supplied as,

Sheets of pink or red colour.

USES –USES –

To make Occlusion rim.To make Occlusion rim.

To form the desired contour of denture after To form the desired contour of denture after

teeth are set.teeth are set.

To make patterns for Orthodontic appliances.To make patterns for Orthodontic appliances.

CLASSIFICATION –CLASSIFICATION –

Type I = Soft ; for building Veneers.Type I = Soft ; for building Veneers.

Type II = MediumType II = Medium

Type III = HardType III = Hard

COMPOSITION –COMPOSITION –

Paraffin wax or Ceresin = 80 %Paraffin wax or Ceresin = 80 %

Beeswax = 12 %Beeswax = 12 %

Carnauba wax = 2.5 %Carnauba wax = 2.5 %

Natural or Synthetic resin = 3 %Natural or Synthetic resin = 3 %

Microcrystalline = 2.5 %Microcrystalline = 2.5 %

PROCESSING WAXPROCESSING WAX

**** Used mainly as accessory aids. Used mainly as accessory aids.

Examples are ,Examples are ,

Boxing Wax & Beading Wax.Boxing Wax & Beading Wax. Utility Wax.Utility Wax. Sticky Wax.Sticky Wax.

BOXING & BEADING WAXBOXING & BEADING WAX

USES --USES --

To build up vertical walls around the impression.To build up vertical walls around the impression.

SUPPLIED AS –SUPPLIED AS –

Boxing wax Boxing wax as sheets.as sheets.

Beading waxBeading wax as strips. as strips.

UTILITY WAXUTILITY WAX

Supplied as – Supplied as – Sticks and Sheets.Sticks and Sheets.

Uses –Uses – To adjust the contour of perforated tray. To adjust the contour of perforated tray.

Composition – Composition – Petrolatum & other waxes.Petrolatum & other waxes.

**** It is adhesive and can stick to the tray.It is adhesive and can stick to the tray.

STICKY WAXSTICKY WAX

USES --USES --

To join metal parts before soldering.To join metal parts before soldering. To join fragments of broken dentures before To join fragments of broken dentures before

repair.repair.

COMPOSITION --COMPOSITION --

Mainly Yellow Beeswax, Rosin & Natural resins Mainly Yellow Beeswax, Rosin & Natural resins such as Gum dammer. such as Gum dammer.

PROPERTIES –PROPERTIES –

Sticky when melted & Adheres closely to surface.Sticky when melted & Adheres closely to surface. Firm and Brittle at room temperature.Firm and Brittle at room temperature.

IMPRESSION WAXESIMPRESSION WAXES

Used to record non – undercut edentulous Used to record non – undercut edentulous portions of the mouth.portions of the mouth.

Examples are ,Examples are ,

** CORRECTIVE IMPRESSION WAX** CORRECTIVE IMPRESSION WAX

** BITE REGISTRATION WAX** BITE REGISTRATION WAX

CORRECTIVE IMPRESSION WAXCORRECTIVE IMPRESSION WAX

USES --USES --

To make functional impression of To make functional impression of RPD.RPD.

To record Posterior Palatal Seal.To record Posterior Palatal Seal. Functional Impression for Functional Impression for

Obturatures.Obturatures.

COMPOSITION --COMPOSITION --• Paraffin waxParaffin wax• Ceresin waxCeresin wax• BeeswaxBeeswax

May contain metal particles.May contain metal particles.

PROPERTIES –PROPERTIES –• FLOW at 37 FLOW at 37 0 0 C is 100 %.C is 100 %.• Should be poured immediately.Should be poured immediately.

BITE REGISTRATION WAXBITE REGISTRATION WAX

USES --USES --

To record the relationship between To record the relationship between the upper andthe upper and

lower teeth.lower teeth.

SUPPLIED AS --SUPPLIED AS -- U shaped rods. U shaped rods.

COMPOSITION -- COMPOSITION -- Beeswax, Beeswax, Paraffin, Ceresin.Paraffin, Ceresin.

MCQsMCQs

1. The role of gum dammar in Inlay 1. The role of gum dammar in Inlay casting wax is:casting wax is:

a) To improve cracking resistancea) To improve cracking resistance

b) To provide strength to waxb) To provide strength to wax

c) To impact smoothness to patternc) To impact smoothness to pattern

d) All of the aboved) All of the above

2. Carnauba was is preffered to 2. Carnauba was is preffered to candelila wax as:candelila wax as:

a)a) It is harder and has less flowIt is harder and has less flow

b)b) It has low melting temperatureIt has low melting temperature

c)c) It provides luster to the patternIt provides luster to the pattern

d)d) All of the aboveAll of the above

3. Inlay wax should have following 3. Inlay wax should have following requisites:requisites:

a)a) Its colour should be in contrast with tooth Its colour should be in contrast with tooth or die materialor die material

b)b) It should have capability to be carved It should have capability to be carved according to tooth anatomy and there according to tooth anatomy and there should be no flaking.should be no flaking.

c)c) When heated, it should be completely When heated, it should be completely eliminated from the mould.eliminated from the mould.

d)d) All of the above.All of the above.

4. Which of the following waxes is 4. Which of the following waxes is used for making of casting pattern:used for making of casting pattern:

a)a) Boxing waxBoxing wax

b)b) Inlay waxInlay wax

c)c) Modeling waxModeling wax

d)d) Utility waxUtility wax

5. The minimum flow of inlay wax at 5. The minimum flow of inlay wax at 454500C should be:C should be:

a)a) 60%60%

b)b) 6%6%

c)c) 70%70%

d)d) 100%100%

6. Which of the following correctly 6. Which of the following correctly describe type I inlay casting wax:describe type I inlay casting wax:

a)a) Soft wax used for direct techniqueSoft wax used for direct technique

b)b) Medium wax used for indirect Medium wax used for indirect techniquetechnique

c)c) Soft wax used for indirect techniqueSoft wax used for indirect technique

d)d) Medium was used for direct Medium was used for direct techniquetechnique

7. The maximum ingredient of inlay 7. The maximum ingredient of inlay casting wax:casting wax:

a)a) Paraffin waxParaffin wax

b)b) CeresinCeresin

c)c) Carnauba waxCarnauba wax

d)d) Gum dammarGum dammar

8. Which of the following is added 8. Which of the following is added inlay casting was to improve the inlay casting was to improve the smoothness:smoothness:

a)a) CeresinCeresin

b)b) Candellila waxCandellila wax

c)c) Gum dammarGum dammar

d)d) Synthetic waxSynthetic wax

9. Percentage of Carnauba wax in 9. Percentage of Carnauba wax in inlay casting wax is:inlay casting wax is:

a)a) 40%40%

b)b) 60%60%

c)c) 25%25%

d)d) 10%10%

10. Inlay casting wax is supplied as:10. Inlay casting wax is supplied as:

a)a) Sheets onlySheets only

b)b) Mesh form onlyMesh form only

c)c) Both of the aboveBoth of the above

d)d) None of the aboveNone of the above