Elastomers

Question 1

How are elastomers formed

Answer 1

by polymerisation with cross-linking of polymer chains

Question 2

What significance does cross linking have when forming elastomers

Answer 2

• generates elastic properties
• causes fluid to solid transition

Question 3

Downside of polymerisation of elastomers

Answer 3

• may produce byproducts
• which affect dimensional stability and cast compatibility

Question 4

Types of elastomers

Answer 4

• silicones
• polyethers
• polysuphides

Question 5

ideal properties of impression materials

Answer 5

• quality of surface interaction between material and tooth/soft tissue surfaces
• accuracy
• dealing with removal and undercuts - high tear and tensile strength
• dimensional stability - low setting shrinkage and thermal expansion/contraction
• low rigidity = easy of remove of material, especially from undercut regions