Definitive casts and dies

Question 1

What are two other terms that synonymous with master cast?

Answer 1

• Definitive cast

- Working cast

Question 2

What is a replica or copy of the prepared tooth or teeth, ridge areas, and other parts of the dental arch known as?

Answer 2

-Master cast

Question 3

What is a die?

Answer 3

-Positive reproduction of the prepared tooth

Question 4

T/F The master cast must accurately represent both prepared and unprepared tooth surfaces

Answer 4

True

Question 5

What must the unprepared teeth immediately adjacent to the prepared teeth be free of the meet the master cast requirements?

Answer 5

• Voids
• Defects
• Irregularities

Question 6

All contacting surfaces of opposing teeth in MI and any tooth surfaces involved in anterior guidance must be free of what to meet mast cast requirements?

Answer 6

• Free of defects

- Allow for precise articulation

Question 7

T/F All relevant soft tissues must be accurately reproduced, especially edentulous ridges that will be involved in fixed prostheses

Answer 7

True

Question 8

For die requirements all _______ areas must be accessible.

Answer 8

Marginal

Question 9

Epoxy resin is _____ abrasion resistant that gypsum.

Answer 9

More

Question 10

Epoxy resin is ____ expensive than gypsum

Answer 10

More

Question 11

What type of impression material must be used for an epoxy resin?

Answer 11

• PVS

- Polyether

Question 12

What type of impression material must be used for a polyurethane?

Answer 12

• PVS

- Polyether

Question 13

Polyurethane is ____ abrasion resistant than gypsum

Answer 13

-More

Question 14

Electroplated is ______ distorted

Answer 14

Easily

Question 15

What is electroplated incompatible with?

Answer 15

• Polyether

- Polysulfide

Question 16

With flexible silicone or polyether the restoration is ___ separated from die.

Answer 16

Easily

Question 17

Gypsum is _______ abraided.

Answer 17

-Easily

Question 18

Gypsum is also known as what?

Answer 18

-Calcium sulfate dihydrate (mined this way)

Question 19

What is calcination?

Answer 19

-The turning of dihydrate gypsum into dental stone (anhydrite)

Question 20

When is the Beta-hemihydrate produced?

Answer 20

-When gypsum is heated in an open ketlle type to produce Type I and Type II Dental plaster or stone

Question 21

Type I and Type II dental stone are what type of hemihydrate?

Answer 21

-Beta

Question 22

Type II Dental stone is what type of hemihydrate?

Answer 22

-Alpha

Question 23

What is alpha-hemihydrate also referred to as?

Answer 23

-Hydrocal

Question 24

When is alpha-hemihydrate produced?

Answer 24

-When gypsum is dehydrated under pressure in the presence of water vapor

Question 25

How is Densite produced?

Answer 25

-Gypsum is boiled in 30% CaCl solutions

Question 26

Type IV, and V dental stone is what?

Answer 26

-Densite

Question 27

What do you use type I stone for?

Answer 27

-Impression plasters and Mounting stone

Question 28

What is Type II stone used for?

Answer 28

-Model plasters

Question 29

What is type III stone used for?

Answer 29

-Model stones

Question 30

What is Type IV stone used for?

Answer 30

-Die stones

Question 31

What is Type V stone used for?

Answer 31

-Die stones

Question 32

What properties does Type IV stone have?

Answer 32

- High strength | - Low expansion

Question 33

What properties does Type V stone have?

Answer 33

- High strength | - High expansion

Question 34

What has the lowest expansion?

Answer 34

-Type I mounting stone

Question 35

What is plaster of Paris?

Answer 35

-Type I dental stone

Question 36

What type of stone do you used for Diagnostic casts, -working casts for Removable complete dentures?

Answer 36

Type III

Question 37

What is the theoretical lowest required volume of water needed to hydrate 100g of hemihydrate?

Answer 37

- 18.6 mL

Question 38

Which type of hemihydrate crystals are smaller, more prismatic and regular in shape?

Answer 38

-Alpha

Question 39

Which type of hemihydrate crystals are larger, more porous and irregular in shape?

Answer 39

-Beta

Question 40

Which type of hemihydrate required more water?

Answer 40

-Beta

Question 41

Which type of hemihydrate produces a harder and stronger set structure?

Answer 41

-Alpha

Question 42

What does adding more water to the mix do to the set time?

Answer 42

-Increase the set time

Question 43

What can decrease the set time of the materials?

Answer 43

- 2% K2SO4 - Slurry mix - Increase water temp

Question 44

If you spatulate more quickly what does it to do the set time?

Answer 44

-Decrease

Question 45

T/F The high strength dental stone contains the least amount of excess water

Answer 45

True

Question 46

How long after mixing and pouring is the gypsum usually at its maximum wet strength?

Answer 46

-1 - 2 hours

Question 47

What is wet strength?

Answer 47

-The strength measured when excess water remains in the hardened mass of stone

Question 48

What is dry strength?

Answer 48

-Stone is its strength with all of the excess water removed.

Question 49

The dry strength is approximately ______ that of the wet strength?

Answer 49

-Twice

Question 50

What is hardness?

Answer 50

-Surface measurement of the resistance of one material to be deformed by indenting or scratching by another material

Question 51

T/F Surface hardness always correlates with abrasion resistance.

Answer 51

False | -They dont always correlate