Elastomeric Impression Materials Flashcards Preview

2 - Dental Material Science > Elastomeric Impression Materials > Flashcards

Flashcards in Elastomeric Impression Materials Deck (13)
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1
Q

What are the two impression materials?

A

Polyether
Addition silicone

2
Q

What are the desirable qualities of an impression material?

A

Accurate detail reproduction
Elastic recovery
High tear strength
Dimensionally stable
Ease of use
Speed of setting

3
Q

What are the ISO standards?

A

Dental Standard – designed to assess relevant properties of a product to see whether it meets acceptable requirements for safe and effective use

4
Q

What is the ISO standard for impressions materials?

A
  • grooves/indentations of either 20um or 50um (depending on material viscosity) are replicated
5
Q

What components in addition silicone ensure exceptional precision and excellent reproduction of anatomical details?

A

The combination of the polymer and spheroid silicon microfillers

6
Q

What does a good wetability mean?

A

Material spreads easily and adapts smoothly to denture and moist oral tissue

7
Q

What is the purpose of the ISO standards?

A

“Standards are NOT designed to establish which is the “best performing” material for a given clinical application ……(instead) they are designed to exclude unsafe and poorly performing materials from the market”

8
Q

What are the ideal properties of impression materials?

A

Viscosity – must be able to flow readily

Surface wetting – must make intimate contact with teeth/mucosa close to 0 degrees is best

Accuracy - surface reproduction and viscosity-elasticity/ elastic recovery

Tear Strength - stress material will withstand before fracturing

Low rigidity - ideally impression material is FLEXIBLE ie has low rigidity, to ease its removal from undercut /interdental regions

9
Q

What is viscosity and what is the different ranges?

A
  • a measure of material’s ability to flow
  • determines a material’s potential for making close contact with hard/soft tissue surfaces
    (how well it records surface detail) - range: low, medium, high
10
Q

What is the ideal elasticity of a material?

A

100% elastic recovery
Recovery from deformation, no permanent strain

11
Q

What should be done to reduce permanent strain/deformation?

A

If LOAD time is less - and impression removed with a sharp pull, there is less overall permanent strain (ie lower deformation)

12
Q

What is the ideal viscoelasticity?

A

when impression material, having been stretched/compressed on removal from mouth, fails to return to its original dimensions/shape

ie there is permanent deformation (permanent strain)

IDEAL – low viscoelasticity (small deformation)

13
Q

What type of material has a shorter working and setting time?

A

Polyether