Dental materials: Waxes

Question 1

What are the properties of waxes?

Answer 1

Thermoplastic- solid @ room temp + melts at high temp with no decomposition
Crystalline structure

Question 2

What are the different types of waxes and what examples for each?

Answer 2

Animal- Beeswax
Vegetable- carnuba/ candelilla
Mineral- Hydrocarbons

Question 3

What types of hydrocarbon waxes are there?

Answer 3

Straight chain- Paraffin
Branched chain- Microcrystalline

Question 4

What is the softening point and melting point of paraffin wax?

Answer 4

SP= 37-55
MP= 48-70

Question 5

What is the melting point of microcrystalline wax?

Answer 5

65-90

Question 6

Why is microcrystalline wax added to paraffin?

Answer 6

to increase MP and decrease SP

Question 7

What waxes are added to paraffin?

Answer 7

Microcrystalline
Beeswax
Carnuba+ candelilla

Question 8

Why is beeswax added to paraffin

Answer 8

To reduce brittleness and flow

Question 9

What is the lost wax technique?

Answer 9

1) restoration is formed on die/cast of prep (indirect) OR on the tooth prep itself (direct)
2) Removed + invested
3) Wax is then boiled/ burnt off

Question 10

What are the applications of dental wax?

Answer 10

-Modelling (indirect)/ inlay (direct)
-Carding
-Boxing
-Joining components- sticky wax

Question 11

What are the ideal properties of wax when constructing acrylic dentures?

Answer 11

-Withstands intraoral temp-> good at the try-in stage
-No tearing/ flaking/ chipping
- No residue when boiled out
- Tough enough for undercut removal

Question 12

What are the ideal properties of wax when constructing crowns/ inlays/ bridges?

Answer 12

-No tearing/ flaking/ chipping
- No residue when boiled out
-Good colour contrast
-Fractures if locked into an undercut