Dent Mat Lec - WAXES

WAXES

• are low molecular weight ester of fatty acids

• derived from synthetic components such as petroleum derivatives, that soften to a plastic state at a relatively low temperature. 

• as an aid for the production of gypsum casts

• production of nonmetallic denture bases

• registering jaw relations

• laboratory work

What are the uses of waxes?

1. Primarily used in the clinics

2. Used in commercial dental labs

How are waxes grouped?

• bite registration wax

• disclosing wax (pressure indicating paste)

• utility wax for altering and adapting impression trays

• low-melting type I inlay wax used in the mouth for direct wax pattern

Those primarily used in the clinics

• boxing wax

• baseplate wax

• sticky wax

• beading wax

• utility wax

• hard, medium, and soft type II inlay wax for indirect wax pattern

Those used in commercial dental labs

1. Pattern waxes

2. Processing wax

3. Impression wax

Waxes can also be classified into 3 types:

• inlay wax

• casting wax

• baseplate wax

What are under the pattern waxes?

• boxing wax

• utility wax

• sticky wax

What are under the processing wax?

• bite registration

• correction wax

What are under the impression wax?

PARAFFIN

• derived from the high boiling fractions of petroleum

• composed of complex mixture of hydrocarbons of methane series and a minor amount of amorphous or microcrystalline phases

• it is moldable below the liquefaction temperature

• it is likely to flake when trimmed

• does not present a smooth, glossy surface (a desirable requisite for an inlay wax

PARAFFIN

main ingredient; most dental waxes consist 40-60 by wt% of paraffin

40-60%

PARAFFIN

main ingredient; most dental waxes consist ______ by wt% of paraffin

GUM DAMMAR

• OR dammar resin,

• s a natural resin

• Added to paraffin improve the smoothness in molding

• Makes the paraffin more resistant to cracking and flaking

• Increases toughness of the wax

• Enhances smoothness and luster of the surface

CARNAUBA WAX

• Occurs as a fine powder on thE leaves or certain tropical palms

• One of the hardest and most durable waxes.

• One of the main components of inlay wax

• Has a relatively high melting point

• Combined with paraffin to decrease the flow at mouth temperature

• Has an agreeable odor

• Also contributes to the glossiness of the wax surface even more than does the dammar resin

CANDELILA WAX

• Added to partially or entirely replace carnauba wax

• Also obtained from plants

• Provides the same general qualities as the carnauba wax

• Has lower melting point

• Not as hard as carnauba wax

CERESIN

• Is typically a white wax extracted from ozokerite, a waxy mineral mixture of hydrocarbons

• IS colorless or white when pure, but it has somewhat unpleasant odor

• May replace part of the paraffin to modify the toughness and carving characteristics of the wax

TYPE 1 OF DENTAL WAX

• Medium wax employed in direct wax pattern technique

• Max. flow permitted at 37°C (98°F) is 1%

  • Permits carving and removal from the cavity w/o distortion

TYPE 2 OF DENTAL WAX

• Soft wax used in the indirect wax pattern wax technique

• Minimal flow 70% at 45°C (113°F) and max flow at 90%

  • Wax is inserted into the prepped cavity and flows into the details of the cavity

DESIRABLE PROPERTIES OF WAXES

1. Should be uniform when softened.

2. The color should be in contrast with the die material or the tooth.

3. There should be no flakiness or roughness when bent or molded.

4. It should have the property of being carved to the margins and conform to the original anatomy of the tooth.

5. It should be eliminated completely from the mold during the burn out process and should leave no excess or residue which will affect the outcome of the cast metal.

6. It should be completely rigid and dimensionally stable at all times until it is eliminated

7. It should have the property of plasticity or flow at a temperature slightly above that of the mouth

shortened:

• Wax should be uniform when softened.

• Its color should contrast with the die material or tooth.

• There should be no flakiness or roughness when bent or molded.

• It should have the property of being carved to the margins and anatomy.

• It must be completely rigid and dimensionally stable until eliminated.

• During burnout, it should be eliminated completely with no residue.

• At slightly above mouth temperature, it should show plasticity or flow.

THERMAL CONDUCTIVITY

• Is low, time is required to heat them uniformly throughout and to cool them to body or room temperature.

• High coefficient of thermal expansion

  • It expands and contracts thermally more per degree temperature change than any other dental materials.

  • Affected by impurities, temperature of the die, and methods used for applying pressure as it solidifies

DISTORTION

Is the most serious problem when forming and removing wax pattern from the mouth!!!

• Thermal changes

• Released stress from contraction on cooling

• Occluded air

• Change of shape during molding, carving, and removal

• Time and temperature during storage

DISTORTION RESULTS FROM:

ELASTIC MEMORY

Waxes RETURN to their original shape after manipulation.

1. Never allow relaxation of the wax.

2. Do not remove the wax while still soft.

3. Avoid thermal changes, or the increase or decrease of temperature

4. Soften the wax homogeneously.

5. Never create undercuts in the cavity.

6. Invest the pattern immediately after removal from the mouth or die.

To prevent distortion:

• Baseplate wax

• Bite wax/corrective wax/impression wax

• Sticky wax

• Boxing wax

SPECIALTY WAXES

BASEPLATE WAX

• used principally to establish the initial arch form in the construction of complete dentures

• supplied in 1-2mm thick red or pink sheets

• made up of approximately 75% paraffin or ceresin with addition of beeswax and other resin or waxes

1-2mm

BASEPLATE WAX

supplied in ______ thick red or pink sheets

75% paraffin or ceresin

BASEPLATE WAX

made up of approximately _______ with addition of beeswax and other resin or waxes

Types of baseplate waxes

• Depends on percentage of flow of each type at room temperature, at mouth temperature and at 45°C (113°F).

• The harder the wax, the less the flow at a given temperature.

TYPE I (BASEPLATE WAXES)

soft wax for building veneers

TYPE II (BASEPLATE WAXES)

medium wax for patterns to be tried in the mouth in normal climactic conditions.

TYPE III (BASEPLATE WAXES)

hard wax for trial fitting in the mouth in tropical climates

• Bite wax

• Corrective wax

• Impression wax

• Limited to use in edentulous portion of the mouth because they distort when withdrawn from undercut areas.

• Quite soft at mouth temperature

• Have sufficient body to register the details of the soft tissue

• Are rigid at room temperature

• Sticky wax

-quite tacky when melted but firm and brittle when cooled.

-Used to join and temporarily stabilize components of a bridge before soldering or the pieces of a broken denture prior to repair.

Sticky wax

• Quite tacky when melted but firm and brittle when cooled.

• Used to join and temporarily stabilize components of a bridge before soldering or the pieces of a broken denture prior to repair.

• Indirect

• Direct

What are the wax patterns?

WAX PATTERN

• The first procedure in the casting of an inlay or crown for the lost-wax pattern technique

• It should be an accurate reproduction of the missing tooth structure

• It forms the outline of the mold into which the gold alloy is cast

• It should be well adapted to the prepared cavity, properly carved with minimal distortion

• It should be invested as soon as possible after removal from the cavity

DIRECT WAX PATTERN

• The wax is carved directly on the tooth itself

• Uses a type I wax or medium wax.

Advantages:

• Less material is used

• Less time-consuming

Disadvantage:

• Difficult to carve

Direct wax pattern technique

1. A stick of wax is softened over a flame. Do not overheat.

2. Twirl the wax until it becomes shiny.

3. Remove from the flame.

4. Repeat the process until the wax is warm throughout.

5. Knead together and shape to the prepared cavity.

6. Use a sprue to remove the pattern from the tooth.

7. Avoid touching the wax with fingers to prevent temperature change.

8. Invest the pattern immediately

Advantages:

• Less material is used

• Less time-consuming

What are the advantages of DIRECT WAX PATTERN?

Disadvantage:

• Difficult to carve

What are the disadvantages of DIRECT WAX PATTERN?

INDIRECT WAX PATTERN

The wax is carved on the die. Uses a type II wax or soft wax

Advantages

• Visibility in carving the pattern

Disadvantages

• More material is used

• More time-consuming

INDIRECT WAX PATTERN TECHNIQUE

1. Lubricate the die. Avoid any excess as it will prevent intimate adaptation to the die

2. Melt the wax and add it by increment or layer into the die using a spatula or brush

3. Overfill the cavity then carve to the proper contour Avoid abrading any surface of the die when carving on the margins.

4. Use a silk cloth for final polishing of the pattern.

5. Invest the pattern immediately.

Advantages

• Visibility in carving the pattern

What are the advantages of INDIRECT WAX PATTERN?

Disadvantages

• More material is used

• More time-consuming

What are the disadvantages of INDIRECT WAX PATTERN?

• Paraffin

• Gum Dummar/Dammar Resin

• Carnauba Wax

• Candelila Wax

• Ceresin

What are composed of waxes?

High boiling fractions of PETROLEUM

Where is Paraffin derived from?

HIGH

Melting point of Carnauba wax

Low and not as hard as carnauba wax

Melting point of Candelilla Wax

Low and not as hard as Carnauba

Melting point of Ceresin

• Low in thermal conductivity

• High in coefficient of thermal expansion

What are the waxes’ thermal property?

THERMAL CONDUCTIVITY

LOW

• Dental waxes have low thermal conductivity, meaning they do not transfer heat quickly.

• Because of this, they require more time to heat uniformly throughout and also to cool down to body or room temperature.

Explanation: This property is important because uneven heating or cooling can cause distortion. When working with wax patterns, they must be warmed or cooled slowly and evenly to maintain accuracy.

COEFFICIENT OF THERMAL EXPANISON

HIGH

• Dental waxes have a high coefficient of thermal expansion, which means they expand and contract significantly with temperature changes — more than most other dental materials.

• This behavior is influenced by factors like impurities, temperature of the die, and the pressure applied during solidification.

Explanation: Because wax expands or contracts a lot, even small temperature changes can alter its size and shape. This must be carefully controlled to avoid inaccuracies in the final cast restorations.