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.

1. Waxes (Thermoplstics) in
Dentistry
1
D R M U M TA Z U L I S L A M
B.Sc. BDS. C. Implant. C. Ortho.
12/5/2013

2. Waxes
2
 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)
12/5/2013

3. Patterns
3
 Direct wax pattern
 Indirect wax pattern
 lost-wax technique
12/5/2013

4. Direct
4
12/5/2013

5. Indirect
5
12/5/2013

6. Types used in dentistry
6
 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)
12/5/2013

7. Waxes
7
12/5/2013

8. Processing wax
8
12/5/2013

9. Full range of processing waxes
9
12/5/2013

10. Modeling wax
10
12/5/2013

11. Modeling wax
11
12/5/2013

12. Wax rims
12
12/5/2013

13. Wax bite blocks
13
12/5/2013

14. Wax bite
14
12/5/2013

15. Wax bite
15
12/5/2013

16. Base Plate Wax
16
12/5/2013

17. Sticky wax
17
12/5/2013

18. Bone wax
18
12/5/2013

19. Ortho wax
19
12/5/2013

20. Ortho wax
20
12/5/2013

21. Requirements of a pattern
21
 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
12/5/2013

22. Sources
22
 Mineral
 Animal
 Vegetable
12/5/2013

23. Mineral
23
 Parrafin wax (straight chain) brittle
 Microcrystalline wax( branched) elastic
 Petrolium byproducts
 Hydrocarbons
12/5/2013

24. Softening and Melting Temperature
24
 Softens at 37 to 55 ͦ C
 Parrafin wax melts at 44 to 70 ͦ C
 Microcrystalline waxes melt at 65 to 90 ͦ C
12/5/2013

25. Animal
25
 Bees wax
 Honey combs
 Partially crystalline natural polyesters
 It can flow under stress just below the melting point
 Very flow able
12/5/2013

26. Vegetable
26
 Derived from trees and plants
 Carnauba wax (Brazil wax or Palm wax)
 Candelilla wax
12/5/2013

27. Properties
27
 Thermal
 Mechanical
12/5/2013

28. Thermal
28
 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
12/5/2013

29. Mechanical
29
 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
12/5/2013

30. Methods of Softening
30
 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
12/5/2013

31. Ideal method for softening
31
 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
12/5/2013

32. Applications
32
 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
12/5/2013

33. Application (contd,)
33
 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
12/5/2013

34. Dimentional Stability
34
 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
12/5/2013

35. Pre-formed Polymeric Components
35
 An alternative to waxes for modelling the metal
components of partial dentures
 Available in sheets
12/5/2013

36. Temporary Denture Bases
36
 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
12/5/2013

37. Shellac
37
 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
12/5/2013

38. Shellac
38
12/5/2013

39. Inlay waxes
39
 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
12/5/2013

40. Requirements
40
 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
12/5/2013

41. Requirements
41
 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
12/5/2013

42. Pattern of Post
42
 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
12/5/2013

43. Indirect Patterns
43
 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
12/5/2013

44. Thank you
44
12/5/2013