Elastomeric Impression Materials Flashcards Preview

BDS2 CLINICAL Dental Materials > Elastomeric Impression Materials > Flashcards

Flashcards in Elastomeric Impression Materials Deck (27)
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1

What are the types of elastomers

Polyether
Additional silicones

2

How should you select an impression material based on

material characteristics
clinical performance (patient acceptance, ease of use)

3

What material properties should you look at

flow/viscosity
surface detail (reproduction)
wettability
elastic recovery (%)
stiffness (flexibility)
tear strength
mixing time
working time

4

What is polyvinylsiloxane

additional silicone

5

What is the ISO standard for impression materials

that grooves/indentations of either 20um or 50um (depending on material viscosity) are replicated

6

What does superior elastic recovery allow

easy to remove from the patient's mouth and elastically recover from the deformation of removal

7

What does high tear strength allow

The excellent tear resistance reduces the risk of tearing fine margins

8

What does good wettability allow

They spread easily and adapt smoothly to dentine and moist oral tissue

9

What are the ideal properties for impressions materials to achieve a good quality of surface interaction between material and tooth/soft tissue surfaces

viscosity
surface wetting
contact angle

10

What are the ideal properties for accuracy

surface reproduction (ISO)
visco-elasticity/elastic recovery

11

What are the ideal properties for dealing with removal and undercuts

tear/tensile strength
rigidity (flexibility)

12

What are ISO standards designed to do

exclude unsafe and poorly performing materials from the market

13

What is viscosity

a measure of material's ability to flow

14

What is surface wetting

must make intimate contact with teeth mucosa

15

What is the contact angle

determines how well material envelops the hard/soft tissue surface (to record fine detail)

16

What does viscosity determine

determines a material potential for making close contact with hard/soft tissue surfaces
so how well it records

17

What does viscosity range from

low, medium, high

18

Why is surface wetting important

so all surfaces are replicated

19

What is the ideal behavior regarding elasticity

100% elastic recovery

20

When is viscoelastic behavior observed

when impression material have been stretched/compressed on removal from out, fails to return to its original dimensions/shape
i.e there is permanent deformation

21

What is the ideal viscoelasticity

small deformation

22

What is tear strength

stress material will withstand before fracturing
important in the material in the undercut

23

What is rigidity

stress/strain
large stress needed to cause the material to change shape
ideally the impression material is flexible

24

If a material has low rigidity what does this allow

to ease its removal from undercut/interdental regions

25

Which has a lower setting time - polyethers or addition silicones

polyether

26

Which has a lower working time - polyethers or addition silicones

polyether

27

How should you make a decision as to what material you are going to use

1. Know the key properties of the material
2. Review product specification data
3. Know typical values expected for specific properties
4. Identify properties not mentioned
5. Reject claims not supported with scientific and/or clinical data