dental waxes Flashcards
Thermoplastic materials that are composed of a mixture of components from natural and synthetic sources
DENTAL WAXES
Composition of dental waxes
Primary components:
- Synthetic waxes
- Natural waxes
*40% -60%
*derived from high-boiling fractions of petroleum
*__ wax is likely to flake when it is trimmed, and it does not produce a smooth, glossy surface.
Paraffin wax
Natural resin
Added to the paraffin to improve the smoothness and luster, increases toughness and resistance to cracking and flaking.
Gum dammar / dammar resin
derived from the fronds of carnauba palm trees
very hard and it has a relatively high melting point
combined with the paraffin to decrease flow at mouth temperature
contributes greater glossiness to the wax surface than dammar resin
Carnauba wax
added partially or entirely replace carnauba wax
provides the same general qualities as carnauba wax but its melting point is lower and it is not as hard as carnauba wax
Candelilla wax
White wax extracted from ozokerite mineral (colorless or white when pure, but it has a somewhat unpleasant odor)
may replace part of the paraffin to modify the toughness and carving characteristics of the wax.
Ceresin
Derived from secretions that bees use to build honeycombs
Reduces brittleness
Beeswax
Gums – harden in air and form sticky, viscous liquid with water
Fats – tasteless, odorless and colorless. Increase melting range and hardness
Oils – soften and improve polishability
Natural resin – Rosin (tree/plant exudates), Shellac (produce by insects) – Harden
natural waxes
Gums, fats, resins
Important Properties of Waxes(M.F.E.T.)
Melting Range
Flow
Excess Residue
Thermal Expansion
→range of temperatures at which each component of wax will start to soften and then flow
❖Usually, the operator does not want the wax to flow but only to soften
❖wax is unstable →operator must be careful to prevent its distortion
❖to prevent distortion →melting range must be higher than the temperature of the environment (especially in hot climates)
Melting Range
❖Movement of wax as molecules slip over each other
❖Dependent on temperature and time
❖as temperature increases, the viscosity of the wax decreases until wax becomes a liquid →flow
❖wax capable of flowing at room temperature →difficult to control
FLOW
❖It is important that all wax be removed from the object into which it is melted
❖If __ remains after wax is removed, this may result in inaccuracies in the object being produced
EXCESS RESIDUE
➢Waxes expand when heated and contract when cooled
The _____ of waxes is greater than that of any other dental material
→If heated above melting range or heated unevenly →expansion above acceptable standards will result
THERMAL EXPANSION
Classification of Waxes
1.Pattern waxes
2.Processing waxes
3.Impression waxes
are used to create a model of a dental restoration such as a crown or partial denture that eventually is cast using the lost-wax technique
→important properties: low thermal expansion, complete removal of excess residue and appropriate melting ranges
3 types: ?
PATTERN WAXES
1.Inlay Wax
2.Casting Wax
3.Baseplate Wax
→Used to produce patterns for metal casting through
the lost wax technique
→Labeled hard, medium and soft (melting range)
→Red, yellow, blue, green
→paraffin, carnauba, ceresin, beeswax
INLAY WAX
→Used to construct the metal framework of partial and complete dentures
→Physical properties similar to inlay waxes with the exception of melting range because not softened in the mouth(lab procedures only)
CASTING WAX
→Sheets of wax that are generally pink in color
→7.5 cm wide x 15 cm long
→usually layered to produce the contours of the denture and hold the position on which denture teeth are set
→Wax must not distort at mouth temperatures
BASEPLATE WAX
→Used primarily to aid in dental procedures both clinically and in the laboratory
3 types:
PROCESSING WAXES
1.Boxing wax
2.Utility wax
3.Sticky wax
→Used to form the base portion of a gypsum model
→4-5cm wide red strip of boxing wax is wrapped around an impression to produce a form into which gypsum is poured
→Easily manipulated at room temperature
BOXING WAX
→Periphery wax
→Comes in long ropes that are easily manipulated at room temperature
→Used to adapt the periphery of the impression tray to customize the tray and aid in patient comfort
→Given to orthodontic patients to cover sharp brackets and wires
UTILITY WAX
→Thermoplastic materials used to obtain impressions of the oral structures
2 types?
. IMPRESSION WAXES
1.Corrective Impression Wax
2.Bite Registration Wax
*used as a wax veneer over an original impression to register the detail of soft tissues in a functional state
*Correct errors of impression from lab
CORRECTIVE IMPRESSION WAX
