impression materials

Question 1

does an impression produce a positive or negative reproduction of tissues?

Answer 1

negative

Question 2

which material is used to fill an impression and produce a positive replica?

Answer 2

dental stone

Question 3

name the 2 clinical classifications of impression materials?

Answer 3

mucostatic

mucocompressive

Question 4

which type of impression material will displace the soft tissues slightly to give an impression of the undisplayed mucosa?

Answer 4

mucostatic

Question 5

which type of impression material is a viscous material that records an impression of the mucosa underpaid?

Answer 5

mucocompressive

Question 6

are low viscosity alginates mucostatic or mucocompressive?

Answer 6

mucostatic

Question 7

are high viscosity alginates mucostatic or mucocompressive?

Answer 7

mucocompressive

Question 8

no impression material is truly elastic, they are instead?

Answer 8

viscoelastic

Question 9

describe viscoelastic?

Answer 9

inhibits both viscous and elastic characteristics when undergoing deformation

Question 10

are lower viscoelastic materials more or less elastic ?

Answer 10

more elastic

Question 11

which creates larger strain, sharply pulling the impression material from the patients mouth or gradually pulling the impression?

Answer 11

gradual pull

Question 12

which properties affect accuracy of an impression?

Answer 12

viscosity - determines ability to flow over surface and record detail
setting mechanisms - does this cause dimensional contraction
thermal expansion coefficient - ideally low
hydrophobic/hydrophillic - affects surface contact
elasticity
tear strength

Question 13

name 2 types of elastic impression materials?

Answer 13

hydrocolloids and elastomers

Question 14

name an irreversible hydrocolloid?

Answer 14

alginate

Question 15

which ions replace which in the alginate reaction?

Answer 15

calcium ions replace sodium