Alginates Flashcards

1
Q

What are three ways alginate can deform?

A
  1. Syneresis - fluid loss from gel to surface (shrinkage)
  2. Evaporation (shrinkage)
  3. Imbibition - swelling if immersed in water (distortion/swelling)
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2
Q

THREE advantages of alginates?

A
  • Easy to use (simple to make and manipulate)
  • Setting time can be manipulated
  • Hydrophilic
  • Relatively cheap
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3
Q

THREE disadvantages of alginates?

A
  • Surface detail not very high (records minimal details)
  • Not dimensionally stable
  • Cannot be poured more than once (single cast)
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4
Q

What is the mixing, working and setting times of Halas Alginate used in ADH?

A
At room temp 23 degrees C:
> Mixing time (45 secs)
> Working time (1 min 45 secs - time to insert into mouth)
> Setting time (30 secs - time in mouth)
Total: 3 mins (purple to pink)
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5
Q

TWO ways setting time of alginate impression material can be manipulated?

A
  1. Water temp

2. W:P ratio

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6
Q

What SEVEN intraoral features should we note before taking impressions?

A
  • Dental arch (shape/size)
  • Palatal vault shape/size (e.g. Tori/exostosis)
  • Axial inclination
  • Mobile teeth
  • Implants
  • Lip tightness
  • Food debris
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7
Q

What FIVE criteria do we use to critique alginates?

A

MSTAR:

  • Mix (homogenous)
  • Size (of tray)
  • Time (set properly)
  • Amount (over/underload)
  • Removal (no drag marks)
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