Impression material Flashcards

1
Q

What are FOUR types of non-aqueous elastomers?

A
  • Polysulfides
  • Condensation silicones
  • Polyethers
  • Polyvinyl Siloxanes (PVS)
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2
Q

Polysulfide:

  • Reaction type and byproduct
  • Disadvantages
A
  • Reaction type: Condensation (SH, Pb2O)
  • Byproduct: H2O
  • Disadvantages: poor dimensional stability (water loss, temp change, continued polymerisation) Offensive odour
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3
Q

Condensation silicones:

- Byproduct

A
  • Byproduct: alcohol (smell)

NOTE: stability: PVS > condensation silicones > polysulfides

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4
Q

PVS:

  • Reaction type and byproduct
  • Advantage
  • Disadvantage
A
  • Reaction type: addition
  • Byproduct: hydrogen gas
  • Advantage: very dimensionally stable
  • Disadvantage: setting retarded by sulfur in latex gloves and astringident solutions
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5
Q

Polyethers:

  • Reaction type
  • Disadvantages
  • Advantage
A
  • Reaction type: cationic polymerisation of imine end groups
  • Disadvantages: very stiff, odour
  • Advantage: very good shelf life (~5yrs)
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