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Flashcards in Gypsum Deck (8)
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1
Q

What is a study model?

A

It is a positive replica of the dentition produced from an impression.

2
Q

What is the purpose of a study model?

A

To record the position and she of teeth.
Aids visualisation and assessment of the dentition.
Enables manufacture of dental protheses.

3
Q

What structure of gypsum determines its properties?

A

Crystalline structure.

4
Q

What are the 4 main uses of gypsum?

A

Cast, die, mould material and investment binder.

5
Q

What are the 3 main types of gypsum?

A
  1. Plaster (beta hemihydrate)
  2. Dental stone (alpha hemihydrate)
  3. Densite (improved stone).
6
Q

How is plaster heated and what are the arrangements of its crystals?

A

Plaster is heated in an open vessel and it has large porous crystals.

7
Q

How is dental stone heated and what are the arrangements of its crystals?

A

It is heated in an autoclave and it it non-porous, regular crystals and it requires less water.

8
Q

How is Densite heated and what are the arrangements of its crystals?

A

It is heated in the presence of calcium and magnesium chloride and it consists of compact smoother particles.