Definitive Casts & Dies

Question 1

A replica of the tooth surfaces, residual ridge areas, and/or other parts of the dental arch and/or facial structures used to fabricate a dental restoration and prosthesis:

Answer 1

Definitive (master or working) cast

Question 2

Definitive cast=

Answer 2

master or working cast

Question 3

The positive reproduction of the form of a prepared tooth in any suitable substance:

Answer 3

die

Question 4

A metal pin used in some stone cast to remove die sections and replace them accurately in the original position:

Answer 4

die pin

Question 5

In a die, the unprepared tooth structure apical to the finish line should be easily visible at:

Answer 5

0.5-1.0mm

Question 6

Advantages of gypsum products:

Answer 6

1. compatible will all impression materials
2. ability to reproduce fine detail & sharp margins
3. dimensional accuracy & stability
4. easy to use

Question 7

What is the disadvantage of gypsum products?

Answer 7

Susceptibility to abrasion

Question 8

ADA Type I & II gypsum products:

Answer 8

Impression plaster/ model & mounting plaster

(plaster)

Question 9

ADA Type III gypsum products:

Answer 9

Dental stone (general purpose cast)

Question 10

ADA Type IV gypsum products:

Answer 10

High strength/lowest expansion (die stone)

Question 11

ADA Type V gypsum products:

Answer 11

High strength/high expansion (die stone)

Question 12

What are the advantages of automixing of gypsum product?

Answer 12

1. homogenous
2. more strength
3. intended expansion

Question 13

What is directly proportional to the water:powder ratio of gypsum products?

Answer 13

Setting times & manipulation

Question 14

Regarding the water:powder ratio of gypsum products:
Describe the directly proportional ratio to increased water

Answer 14

Increased water= increased setting time; increased fluidity

Question 15

What is indirectly proportional to the water:powder ratio of gypsum products?

Answer 15

Compression strength & setting expansion

Question 16

Describe the inverse relationships of gypsum products with an increase in water:

Answer 16

Increased water= decreased compressive strength; decreased setting expansion

Question 17

Surface hardness does not equal:

Answer 17

abrasion resistance

Question 18

A replica of the tooth surfaces, residual ridge areas, and/or other parts of the dental arch and/or facial structures used to FABRICATE a dental restoration or prosthesis:

Answer 18

Definitive (master or working) cast

Question 19

The positive reproduction of the form of a PREPARED tooth in any suitable substance:

Answer 19

Die

Question 20

A metal pin used in stone casts to remove die sections and to replace them accurately in the original position:

Answer 20

Die pin

Question 21

Definitive cast die requirements:

Answer 21

1. bubble free
2. distortion free
3. must reproduce both prepared & unprepared tooth surfaces
4. all occluding surfaces must allow for precise articulation of the opposing casts
5. all relevant soft tissues should be reproduced

Question 22

Die requirements:

Answer 22

1. reproduces the prepared tooth exactly
2. all surfaces must be accurately duplicated
3. no bubbles
4. no voids
5. finish line should be especially accurate
6. unprepared tooth structure 0.5mm apical to finish line should be visible
7. adequate access for carving wax pattern margin
8. correct cervical contour of restoration

Question 23

Types I-V gypsum stones:

Type I:
Type II:
Type III:
Type IV:
Type V:

Answer 23

Type I: impression plaster
Type II: model/mounting plaster
Type III: dental stone (general purpose cast)
Type IV: high strength/low expansion (die stone)
Type V: high strength/high expansion (die stone)

Question 24

Desirable properties of die materials:

Answer 24

1. accuracy
2. ability to reproduce fine detail
3. strong & durable (strength resistance & abrasion resistance)
4. color (should contrast with wax, scanning visibility for CAD/CAM)

Question 25

Water:powder ratio= the _____ amount of water necessary to obtain proper manipulation of stone. You should use the manufacturers recommendations. Add powder to liquid (allows for proper wetting)

Answer 25

LEAST

Question 26

INCREASED water DIRECTLY leads to INCREASED:

Answer 26

Setting time & fluidity

Question 27

INCREASED water INDIRECTLY leads to DECREASED:

Answer 27

Compressive strength & setting time

Question 28

May result in unset or powdery gypsum on the surface:

Answer 28

disinfectant

Question 29

Dry strength is _______ x stronger than wet strength

Answer 29

2

Question 30

When gypsum is immersed in water (per every 20 min of immersion) linear dimension decreases, this describes:

Answer 30

solubility

Question 31

What happens to the gypsum material when immersed in water with calcium sulfate slurry?

Answer 31

Solubility decreases

Question 32

Surfaces impregnation of gypsum products uses:

Answer 32

cyanoacrylate cement