Clinical failures Flashcards

1
Q

rough or uneven impression surface

A
  • incompletepolymerization
  • improper mixing or ratio of components
  • FOR ADDITION SILICON= surface agents like latex contaminate material and inhibit polymerization
  • FOR CONDENSED SILICON= excessively high accelerator/base ratio with
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2
Q

bubbles

A

air incorporated when mixing

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3
Q

irregularly shaped voids

A

moisture or debris on surface of teeth

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4
Q

rough or chalky stone cast

A
  • inadequate cleaning of impression
  • excess water still present
  • excess wetting agent still on impression
  • premature removal of caste
  • improper W/P ratio
  • ADDITION SILICON= failure to delay pour for at least 20 minutes (so it doesn’t contain salt?)
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5
Q

distortion

A

*movement of tray during polymerization
*resin tray not aged sufficiently
*lack of adhesion of elastomer to tray
*excessive bulk of materiel used
*elastic properties develop in material before tray is set
*premature or improper removal of impression from mouth
delayed pouring of addition silicone or condensed silicon impression
*lack of mechanical retention to impression tray

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6
Q

Inadequate bulk causes what?

A

Tearing

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7
Q

Leaving case in impression too long causes what?

A

Rough or chalky cast

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8
Q

Having a too low W/P ratio causes?

A

Grainy material

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9
Q

Impression not poured immediately causes?

A

Distortion

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10
Q

Air incorporation during mixing causes?

A

Bubbles

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