Elastomeric Impression Materials

Question 1

what are the two types of elastomer

Answer 1

polyether and addition silicones

Question 2

Shore A hardness

Answer 2

specific hardness test for impression materials

Question 3

what does the shark fin test test

Answer 3

ability of an impression material to deal with an undercut

Question 4

ideal viscosity of an impression material

Answer 4

ideally a low viscosity so it can flow readily and make close contact with tissues and record surface detail

Question 5

ideal surface wetting of impression materials

Answer 5

ideally a low contact angle so all of surface can be covered and replicated

Question 6

what is the minimum surface reproduction an impression material should have

Answer 6

50 um

Question 7

ideal tear strength of impression materials

Answer 7

high tear strength essential so that it doesn’t tear upon removal

Question 8

ideal rigidity of impression materials

Answer 8

should be low - flexible enough for removal particularly in undercut areas

Question 9

compare addition silicones and polyethers
- working time

Answer 9

addition silicones - 4 mins
polyethers - 6 mins

Question 10

compare addition silicones and polyethers
- setting time

Answer 10

addition silicones - 6 mins
polyethers - 5 mins

Question 11

are polyethers or addition silicones better for deep undercuts

Answer 11

polyethers

Question 12

do polyethers or addition silicones have higher tear strength

Answer 12

addition silicones