This document discusses the use and properties of waxes in dentistry. Waxes are thermoplastic materials that are solid at room temperature but soften and become malleable when heated, allowing them to be molded. In dentistry, waxes are used to form patterns and models, including direct patterns made in a patient's mouth and indirect patterns made from impressions. Different waxes have different properties suitable for tasks like denture construction, taking impressions, or forming inlays and posts. The document outlines the sources of waxes, their thermal and mechanical properties, and applications in dentistry.
2. Waxes
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Waxes are thermoplastic materials
Soft on heating hard on cooling
Solid at room temperature
Melt without decomposition
Form mobile liquids
Poor mechanical properties
Used to form patterns (wax pattern)
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6. Types used in dentistry
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Fixing denture teeth for displaying (carding wax)
Boxing in dentures before making the model (boxing-in
wax)
Temporary joining two broken pieces (sticky wax)
For taking impression (impression waxes)
To control hemeostasis (bone wax)
In endodontics (gutta percha)
In orthodontics (orthowax)
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21. Requirements of a pattern
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Copy exact size Shape & Contour
Dimensionally stable after formation of pattern
Easily be removed after mould formation
For indirect use its melting point should be above room
temperature
For direct use it should set at mouth temperature
Molding temperature
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24. Softening and Melting Temperature
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Softens at 37 to 55 ͦ C
Parrafin wax melts at 44 to 70 ͦ C
Microcrystalline waxes melt at 65 to 90 ͦ C
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25. Animal
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Bees wax
Honey combs
Partially crystalline natural polyesters
It can flow under stress just below the melting point
Very flow able
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26. Vegetable
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Derived from trees and plants
Carnauba wax (Brazil wax or Palm wax)
Candelilla wax
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28. Thermal
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Melting point
Solid-solid transition temperature (lower than melting
point) brittle state changes into a mouldable and softer
material
Softening temperature just above the mouth temperature
Poor thermal conductor (must be kept above SST for
thorough softnening)
High coefficient of thermal expansion
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29. Mechanical
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Flow more during moulding and no flow at mouth or
room temperature prevents distortion
Brittleness inherent property can be controlled desired in
inlay wax
Toughness more desirable in wax denture base
Internal stress
Dimentional changes
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30. Methods of Softening
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water bath
Infra-red lamp 250 watts
Bunsen burner
It should not touch the flame
Glossy (shiny) appearance indicates melting outer surface
In water uniform but leaching of constiuents occours
Water incorporation also alters its composition and
properties
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31. Ideal method for softening
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Wax annealer
Thermostatically controlled oven which keeps the wax at
a constant temperature
just above the softening point
Ready for use
The annealer is most useful for inlay waxes
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32. Applications
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Processing waxes
Denture modeling wax
Wax rim
Mounting artificial teeth on that rim
Three types
Type 1 soft
Type 2 hard
Type 3 extra hard
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33. Application (contd,)
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Type 1 material
Hard at room temperature but soft at mouth temperature
Building contours and veneers in the laboratory
The type 2 material
For pattern production in temperate climate
Type 3 material
For use in warmer climates
Modelling waxes consist mainly of mixtures of paraffin
wax and beeswax and have melting points in the range
49–58ºC
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34. Dimentional Stability
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High values of coefficient of thermal expansion
Manner in which the materials are used (softening with
heat and cooling) suggests that a significant dimensional
change can occur
An upper limit of 0.8% expansion on heating from 25ºC
to 40ºC is allowed in the ISO specification
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35. Pre-formed Polymeric Components
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An alternative to waxes for modelling the metal
components of partial dentures
Available in sheets
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36. Temporary Denture Bases
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Constructed from wax and used during denture
construction are prone to distortions unless great care is
taken
For this reason alternative materials/techniques are
sometimes used
Shellac a wax-like resin which is more stable at mouth
temperature has been used for construction of the
temporary denture base
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37. Shellac
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Natural beetle exudate which has a considerably higher
softening temperature than ordinary modelling wax
Care must be taken to ensure thorough softening prior to
moulding otherwise considerable stresses are introduced
which eventually lead to distortion
The wax rim is then built on top of this more stable base
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39. Inlay waxes
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Inlays or cast posts etc produced by patterns
Direct
Indirect
Two types of inlay casting waxes
Type 1 soft indirect
Type 2 hard direct (may be used indirectly)
Presentation is in the form of cones, sticks and cakes
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40. Requirements
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Should soften just above mouth temperature
Magnitude of thermal contraction and internal stresses
should be minimum
Softening temperature must be tolerated without pain by
the patient
Thermal contraction occurring on removal of the direct
pattern material from the mouth is 0.1–0.5%
Investing the pattern as soon as possible is required
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41. Requirements
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Hard at mouth temperature
On removal from the cavity fractures not to flow
This enables the undercuts to be located and removed
Good colour contrast with enamel
Easy to carve without flaking
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42. Pattern of Post
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The post channel is usually prepared using a proprietary
system and a pre-formed pattern for the post is installed
into the canal
The core is then built up in wax by melting the wax on an
instrument and carrying the molten wax into the tooth
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43. Indirect Patterns
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Soft type
Some what same like direct
Softens at lower temperature than direct
No flow at room temperature
Thermal contraction is much lower as lower softening
temperature
A distinct advantage of the indirect technique
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