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Dental Materials Y3 > Dental Waxes > Flashcards

Dental Waxes Flashcards

1
Q

What state are dental waxes in at room temperature

A

solid

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2
Q

Why do we heat dental waxes

A

Heating converts the wax to a liquid phase that makes it easily mouldable

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3
Q

why do manufacturers of dental waxes blend 2 or more waxes together

A

this gives the material a softening temperature range over which it is a useful mouldable material

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4
Q

What rough melting range do we want a dental wax to have on clinic and why

A

Only slightly higher than the mouth temperature as any higher would make it uncomfortable for the patient

Note: In Labs, waxes may have a much higher melting range

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5
Q

Why is thermal expansion very important in dental waxes relative to other dental materials

A

Dental waxes have a higher thermal expansion and contraction than any other dental material

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6
Q

What can happen if a wax is heated too far above the melting range or is heated unevenly

A

This will cause expansion above the acceptable standards and cause inaccuracies in the final casting

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7
Q

What can cause dimensional changes in dental waxes on standing

A

The release of residual stresses

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8
Q

What are dental waxes composed of

A

Of a synthetic and then 2 or more natural waxes and small amounts of additives

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9
Q

Describe some properties of natural waxes that are added to dental waxes

A
  • High molecular weight

- complex combination of organic compounds

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10
Q

Name some of the natural waxes that can be added to dental waxes

A
  • Paraffin
  • Microcrystalline
  • Ceresin
  • Carnauba
  • Cendelilla
  • Beeswax
  • Spermaceti
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11
Q

What is the melting range of paraffin

A

40-70C

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12
Q

What is the melting range of Microcrystalline

A

60-90C

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13
Q

What is the melting range of Ceresin

A

61-78C

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14
Q

What is ceresin used for in dental waxes

A

to increase the melting range of paraffin wax

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15
Q

What is the melting range of carnauba

A

84-91C

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16
Q

What is carnauba used for in dental waxes

A

Increases the melting range and hardness of paraffin wax

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17
Q

What is the melting range of candelilla

A

68-75C

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18
Q

What is candelilla used for in dental waxes

A

Hardens paraffin wax

19
Q

What is the melting range of beeswax

A

63-70C

20
Q

Give some examples of synthetic waxes used in dental waxes

A
  • Polyethylene
  • Polyoxyethylene glycol
  • Halogenated hydrocarbon
  • Hydrogenated Hydrocarbon
  • Wax esters
21
Q

What are the melting ranges of polyethylene and polyoxyethylene glycol

A
  • Polyethylene = 100-105C

- Polyoxyethylene glycol = 37-63C

22
Q

What kinds of additives are used in dental waxes

A
  • Gums
  • Fats
  • Resins
23
Q

How are natural waxes classified according to origin

A
  • Mineral = Paraffin, Microcrystalline, ceresin
  • Plant = Carnauba, Candelilla
  • Animal = Beeswax, Spermaceti
24
Q

How do mineral and plant waxes differ based on their chemical structures

A
  • Mineral waxes = hydrocarbons ranging from 17-44 C atoms

- Plant waxes = saturated alkanes ranging from 19-31 C atoms

25
Q

How can dental waxes be classified based on their uses

A
  • Pattern waxes = Inlay, casting and modelling waxes
  • Processing wax = Boxing, Utility and Sticky waxes
  • Impression wax = Occlusal registration and Corrective waxes
26
Q

What kind of wax is an inlay wax

A

A pattern wax

27
Q

What types of inlay wax are there and what are their uses

A
  • Type 1 (medium) - Direct techniques

- Type 2 (soft wax) - Indirect techniques

28
Q

Name some restorations that use inlay waxes

A

Inlays, onlays and crowns - these are first made in wax and then converted into metal

Inlay waxes can be used for making patterns of metallic restorations

29
Q

What are the constituents of inlay pattern waxes

A
  • Paraffin - 60%
  • Carnauba - 25%
  • Ceresin - 10%
  • Beeswax - 4%
  • Dammar resin - 1%
30
Q

What properties makes paraffin need additives

A

It is weak and flakes on trimming

31
Q

What does dammar resin do to inlay pattern waxes

A

improves smoothness, resistance to cracking and flaking and imparts gloss to surface

32
Q

What are casting waxes used for

A

Used in patterns for denture framework ie construct the metal framework of partial and complete dentures

33
Q

What classes of casting wax are there and describe their features

A
  • Class A: 28 gauge, 0.4mm, pink
  • Class B: 30 gauge, 0.32mm, green
  • Class C: ready made shapes, blue
34
Q

What are the properties of casting waxes

A
  • Adaptable at 40-45C
  • Not brittle on cooling
  • Highly ductile
  • Burnt out without leaving residue?
35
Q

What is modelling wax also called

A

Baseplate wax

36
Q

What is baseplate/modelling wax used for

A

Setting up of artificial teeth for full dentures

37
Q

What are the constituents of modelling/baselpate wax

A
  • Paraffin or cersin (70-80%)
  • Beeswax (12%)
  • Carnauba (2.5%)
  • Natural or synthetic resins (3%)
  • Microcrystalline or synthetic waxes (2.5%)
38
Q

What kind of wax is sticky wax

A

A processing wax

39
Q

What is sticky wax used for

A

Its an adhesive wax that is used for the temporary joining of items
- e.g. align fractured parts of acrylic dentures, align fixed partial parts before soldering

40
Q

What are the constituents of sticky wax

A
  • Resin
  • Yellow beeswax
  • Gum dammar
41
Q

What are the properties of sticky wax

A
  • At RT = hard and brittle
  • When melted it adheres closely to the applied surface
  • Sticky when melted
  • Fractures when movement occurs
42
Q

What is impression wax used for

A

Occlusal Registry

Corrective for edentulous impressions

43
Q

What are the constituents of impression wax

A
  • Hydrocarbon waxes (paraffin, ceresin and beeswax)

- Metal particles (Al or Cu)

44
Q

What are the properties of impression wax

A
  • Limited to edentulous portions of mouth as it distorts when withdrawn from undercut areas
  • Soft at mouth temperature - flows at mouth temp (rigid at RT)
  • Available in sheets and cakes

Dental Materials Y3 (9 decks)

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