Impression Materials

Question 1

mucostatic definition and imp examples

Answer 1

slightly displaces tissues
“undisplayed” mucosa

ZOE, low viscosity alginate

Question 2

mucocompressive definition and imp examples

Answer 2

viscous, under load, “displaced” mucosa

impression compound, high viscosity alginate/elastomers

Question 3

ideal properties of impression materials

Answer 3

surface wetting, inimate
high surface reproduction
high elastic recovery
high tear strength
high flexibility
low setting shrinkage
low thermal expansion
non-toxic
acceptable taste/smell
cheap

Question 4

name elastic impression materials

Answer 4

hydrocolloids - agar, alginate
elastomers - polyether, polysulphide, silicone

Question 5

what is the setting reaction of alginate

Answer 5

sodium alginate -> calcium alginate

trisodium phosphate preferentially reacts with ca
calcium crosslinking

Question 6

properties of alginate

Answer 6

ok accuracy
easy use
poor tear strength
cheap
needs cast asap as dimensional change [synergis, inhibition]

Question 7

how are elastomers formed

Answer 7

polymerisation
via crosslinking polymer chains

Question 8

brand name for polyether

Answer 8

impregum

Question 9

brand name for addition cured silicone

Answer 9

polyvinylsiloxane

Question 10

examples of non-elastic impression materials

Answer 10

rigid, cannot be removed from undercuts without distortion

impression compound
ZOE