Gypsum Products (general info) Quiz 2

Question 1

What is gypsum?

Answer 1

naturally occuring mineral which is mined from the earth’s crust

Question 2

What happens when gypsum is heated? What’s the process called?

Answer 2

it is calcinated. Water is driven off through a process called calcining

Question 3

What are the final products when gypsum is calcinated?

Answer 3

plaster and stone

Question 4

Examples of dentalgypsum

Answer 4

1) impression plaster
2) plaster
3) stone
4) binder in investments

Question 5

What is plaster used for?

Answer 5

models

Question 6

What is stone used for?

Answer 6

models, dies

Question 7

What are investments?

Answer 7

investment is the mold into which metals are cast

Question 8

What does it mean that gypsum is a “binder in investment”?

Answer 8

gypsum product serves as the matrix which holds the investment together (Ex: cement in concrete)

Question 9

What is a model or caste?

Answer 9

replicas of oral structures

Question 10

What are models or casts used for?

Answer 10

1) indirect restorative procedures
2) diagnosis and treatment planning
3) records (for orthodontic treatment progress)

Question 11

Dies

Answer 11

are a removable part of a model which are typically used to replicate a single tooth

Question 12

What is gypsums chemical format?

Answer 12

calcium sulfate CaSO4*2H2O

Question 13

Write the heating equation from dihydrate to hemihydrate

Answer 13

CaSO42H2O —–> CaSO41/2H2O+3/2H2O

Question 14

How is plaster formed? Characteristics?

Answer 14

by heating gypsum in the air at 110-120C. Porous and irregularly shaped particles

Question 15

How is stone formed? Characteristics?

Answer 15

By heating gypsum in the air at 120-130C in an autoclave. Dense and regularly shaped particles

Question 16

What the importance of the autoclave when making stone from gypsum?

Answer 16

generates steam and pressure. Makes more regularly shaped particles

Question 17

How is die stone made? Characteristics?

Answer 17

process varies depending on manufacturer but similar to making stone. Harder and denser than stone

Question 18

What is die stone used for?

Answer 18

dies in crowns and bridge construction

Question 19

Once gypsum products are formed, they are ground into?

Answer 19

various sized powder particles

Question 20

Manufacturers control?

Answer 20

1) particle size
2) particle distribution
3) packing density of the gypsum product

Question 21

Order of least to most porous?

Answer 21

die stone -> stone -> plaster

Question 22

Order of most reguarly shaped to least?

Answer 22

die stone -> stone -> plaster

Question 23

Order of lowest packing density to most?

Answer 23

plaster -> stone -> die stone