Waxes

Dental waxes

thermoplastic materials which are normally solids at room temperature, but melt, without decomposition, to form flowy liquids

Natural waxes

complex combination of organic compounds of high molecular weights

• It is the primary component of dental wax

Carnauba and Candelilla (Vegetable)

Blended with paraffin wax in order to control the softening temperature and modify properties.

Beeswax

The effect of adding this to paraffin wax is to render the material less brittle and reduce the extent to which it will flow under stress at temperatures just below the melting point

Synthetic waxes

High degree of refinement with no contamination

• Polyethylene waxes

• Polyoxyethylene glycol waxes

• Halogenated hydrocarbon waxes

• Hydrogenated waxes

• Waxes ester

Fats

Increase the melting range and the hardness of compound waxes.

Hydrocarbon oils

soften mixture of waxes

Silicone oils

improve the ease of polishing with waxes

Resins

improves toughness, hardness, melting range of waxes

Melting range

waxes consist of similar type of molecules of different molecular weight

• they have melting range rather than melting point

Excess residue

wax should not leave a residue which would affect the quality of the restoration

Thermal expansion

waxes have the highest coefficient of thermal expansion

Expands

when temperature is increased

Contract

when temperature is decreased

Residual stress

Manipulation during heating, cooling, bending → stress in wax → increase in wax temperature→ stress is released → irreversible deformation of wax pattern

To prevent stress formation

• wax must be carved with warm instruments

• Melted wax must be added in small increments

To prevent release of residual stress

• wax pattern must not be stored at high temperature

• Decrease time between finishing and investing wax pattern

low

the elastic modulus, proportional limit and compressive strength of waxes are ___ compared eith those of other materials

Ductility

increases when the temperature of wax is increased

Pattern wax

Used to form the general predetermined size and contour of artificial dental restoration, which is to be constructed of a more durable material

Inlay wax

Used to fabricate working patterns for crowns, inlays and bridges

• Form - as round sticks with various colors

Casting wax

Used to make working patterns of metallic framework of RPD

• Form - as sheets and ready made shapes

Baseplate wax

Used to build contours of dentures and hold denture teeth in place before processing

• Form - as sheets, red or pink

Composition of Inlay pattern wax

paraffin, carnauba, ceresin, beeswax

Type I wax

a hard wax that is prescribed for forming direct patterns in the mouth

Type II wax

a softer wax that is used as an indirect technique wax.

Casting wax

Copies accurately the surface against which it is pressed

• Pliable and readily adaptable at 40 to 45 C

• Vaporize at 500C, leaving no film other than carbon

Baseplate wax

derives its name from its use on the baseplate tray in the technique for complete denture restoration

Processing wax

Used primarily as auxillary aids in fabricating models of a variety of restorations and appliances either clinically or in the laboratory

Boxing wax

helps contain stone around impressions when pouring

• Form: long strips

• Pliable at 21C, retain shape at 35C

Utility wax

to extent periphery of impression trays or reduce irritation of soft tissues by it

• Form: long beads

• Pliable at 21 to 24C

• Tacky at 21 to 24C

Sticky wax

used to assemble metallic pieces temporarily in place

Bite registration wax

Used to articulate models of opposing arches

• Formulated from beeswax or hydrocarbon waxes such as paraffin or ceresin and contain alumina or copper particle