Gypsum Flashcards Preview

Dental Materials > Gypsum > Flashcards

Flashcards in Gypsum Deck (12):
1

What is Gypsum material used for?

model/ die material

2

What properties does gypsum have?

dimensional accuracy
fluid when poured
good wetting
compatible with all materials

3

What products are used for models/dies?

dental plaster
dental stone
densite

4

What has highest porosity and particle size?

plaster

5

How is gypsum used to make plaster?

heated at 120 degrees

6

How is gypsum used to make densite?

boiled in calcium chloride

7

How is gypsum used to make dental stone?

steam pressured

8

What are the stages of setting re. gypsum?

1st stage: water becomes saturated with hemihydrate 0.8% sol
2nd stage: conversion of hemihydrate to dehydrate
3rd stage: dihydrate crystalises out

9

What is setting accompanied by?

increased viscosity
exothermic- up to 30 degrees
expansion

10

What is a retarder of gypsum setting?

Borax

11

What is an accelerator of gypsum setting?

K2So4

12

What is colour code re. dyes?

white: plaster
yellow: stone
blue/pink: die stone