Question 1

Which of the following statements is true of the compressive strengths of gypsum materials?

Accepted Answer

A)  Die stone has the lowest compressive strength, because it has the least excess water. 
B)  Die stone has the lowest compressive strength, because it has the most excess water. 
C)  Die stone is almost four times as strong in compression as plaster, because the excess water is minimized. 
D)  Die stone is almost four times as strong in compression as plaster, because the excess water is maximized. 
A)  Die stone has the lowest compressive strength, because it has the least excess water. 
B)  Die stone has the lowest compressive strength, because it has the most excess water. 
C)  Die stone is almost four times as strong in compression as plaster, because the excess water is minimized. 
D)  Die stone is almost four times as strong in compression as plaster, because the excess water is maximized.

Question 2

Which use of gypsum is hardness and abrasion resistance especially important for?

Accepted Answer

A)  Orthodontic models 
B)  Study models 
C)  Dies 
D)  Casts 
A)  Orthodontic models 
B)  Study models 
C)  Dies 
D)  Casts

Question 3

How should gypsum powder and water be added to the mixing bowl?

Accepted Answer

A)  Water should be added first. 
B)  Powder should be added first. 
C)  The second material added should be sprinkled in slowly over a period of about 30 seconds. 
D)  Both A and C 
E)  Both B and C 
A)  Water should be added first. 
B)  Powder should be added first. 
C)  The second material added should be sprinkled in slowly over a period of about 30 seconds. 
D)  Both A and C 
E)  Both B and C

Question 4

The ________ and ______ dense the crystal of the hemihydrate, the less excess water required to get a workable mass.

Accepted Answer

A)  larger; more 
B)  larger; less 
C)  smaller; more 
D)  smaller; less 
A)  larger; more 
B)  larger; less 
C)  smaller; more 
D)  smaller; less

Question 5

Which form of dental gypsum product is created by boiling gypsum in a 30% solution of calcium chloride?

Accepted Answer

A)  Dental stone 
B)  Model plaster 
C)  High-strength dental stone 
D)  A and B 
E)  B and C 
A)  Dental stone 
B)  Model plaster 
C)  High-strength dental stone 
D)  A and B 
E)  B and C

Question 6

If the mixing water temperature ___________ the hemihydrate will not set.

Accepted Answer

A)  is above 37.5° C 
B)  is below 37.5° C 
C)  reaches 100° C 
A)  is above 37.5° C 
B)  is below 37.5° C 
C)  reaches 100° C

Question 7

Which of the following types of dental stones and dental plasters requires the least amount of excess water?

Accepted Answer

A)  Dental stone 
B)  Model plaster 
C)  High-strength dental stone 
A)  Dental stone 
B)  Model plaster 
C)  High-strength dental stone

Question 8

Which of the following is not a method for pouring a gypsum model base?

Accepted Answer

A)  Pile mound onto a smooth, non-stick surface. 
B)  Wrap the impression with boxing wax. 
C)  Over-pour the impression and invert. 
D)  Fill a base former. 
A)  Pile mound onto a smooth, non-stick surface. 
B)  Wrap the impression with boxing wax. 
C)  Over-pour the impression and invert. 
D)  Fill a base former.

Question 9

Accelerators are chemicals that ________ the rate of setting and ________ the time of setting.

Accepted Answer

A)  increase; increase 
B)  increase; decrease 
C)  decrease; increase 
D)  decrease; decrease 
A)  increase; increase 
B)  increase; decrease 
C)  decrease; increase 
D)  decrease; decrease

Question 10

Which of the following materials will accelerate the setting reaction of gypsum products?

Accepted Answer

A)  Agar 
B)  Blood 
C)  Saliva 
D)  Terra alba 
E)  Unset alginate 
A)  Agar 
B)  Blood 
C)  Saliva 
D)  Terra alba 
E)  Unset alginate

Question 11

Which of the following statements is true regarding disinfection of a gypsum model?

Accepted Answer

A)  The model may be sterilized in an autoclave. 
B)  Disinfecting the impression rather than the model is preferable. 
C)  Disinfecting the model rather than the impression is preferable. 
D)  A and B are true statements. 
E)  A and C are true statements. 
A)  The model may be sterilized in an autoclave. 
B)  Disinfecting the impression rather than the model is preferable. 
C)  Disinfecting the model rather than the impression is preferable. 
D)  A and B are true statements. 
E)  A and C are true statements.

Question 12

The impression should not be removed from the gypsum for _______ minutes.

Accepted Answer

A)  3 to 5 
B)  5 to 10 
C)  10 to 20 
D)  20 to 40 
E)  45 to 60 
A)  3 to 5 
B)  5 to 10 
C)  10 to 20 
D)  20 to 40 
E)  45 to 60

Question 13

Which statement(s) is (are) correct about making models, casts, and dies?

Accepted Answer

A)  Fine detail is not significant. 
B)  Gypsums are not dimensionally stable. 
C)  The material does not need to be strong. 
D)  A, B, and C are all correct. 
E)  A, B, and C are all incorrect. 
A)  Fine detail is not significant. 
B)  Gypsums are not dimensionally stable. 
C)  The material does not need to be strong. 
D)  A, B, and C are all correct. 
E)  A, B, and C are all incorrect.

Question 14

Which statement is correct regarding epoxy dies?

Accepted Answer

A)  Works best with alginate 
B)  Low resistance to scratches 
C)  They are dimensionally stable. 
D)  They are a two-component system. 
A)  Works best with alginate 
B)  Low resistance to scratches 
C)  They are dimensionally stable. 
D)  They are a two-component system.

Question 15

When a model or die is wet, its compressive and tensile strength is approximately ____________ its strength when dry.

Accepted Answer

A)  four times 
B)  twice 
C)  one-half 
D)  one-quarter 
E)  one-sixteenth 
A)  four times 
B)  twice 
C)  one-half 
D)  one-quarter 
E)  one-sixteenth

Question 16

Which of the following chemicals is an effective accelerator for gypsum materials?

Accepted Answer

A)  Borax 
B)  Calcium sulfate 
C)  Potassium sulfate 
D)  B-calcium sulfate hemihydrate 
E)  A-calcium sulfate hemihydrate 
A)  Borax 
B)  Calcium sulfate 
C)  Potassium sulfate 
D)  B-calcium sulfate hemihydrate 
E)  A-calcium sulfate hemihydrate

Question 17

Epoxy materials are compatible with most of the elastomeric impression materials. Epoxy materials can be used with alginates.

Accepted Answer

A)  Statement 1 is correct; statement 2 is correct. 
B)  Statement 1 is correct; statement 2 is incorrect. 
C)  Statement 1 is incorrect; statement 2 is correct. 
D)  Statement 1 is incorrect; statement 2 is incorrect. 
A)  Statement 1 is correct; statement 2 is correct. 
B)  Statement 1 is correct; statement 2 is incorrect. 
C)  Statement 1 is incorrect; statement 2 is correct. 
D)  Statement 1 is incorrect; statement 2 is incorrect.

Question 18

Which of the following statements is true of the handling of an alginate impression?

Accepted Answer

A)  The heat produced is the result of an endothermic reaction. 
B)  Any residual water in low places of the impression should not be removed. 
C)  The poured impression may be kept moist by storing it in a humid environment. 
D)  An alginate impression should be rinsed completely and disinfected after pouring. 
A)  The heat produced is the result of an endothermic reaction. 
B)  Any residual water in low places of the impression should not be removed. 
C)  The poured impression may be kept moist by storing it in a humid environment. 
D)  An alginate impression should be rinsed completely and disinfected after pouring.

Question 19

Gypsum model and die materials exhibit ________ in contrast to epoxy model and die materials.

Accepted Answer

A)  excellent compatibility with impression materials 
B)  excellent abrasion resistance 
C)  slight expansion 
D)  both A and C 
E)  both B and C 
A)  excellent compatibility with impression materials 
B)  excellent abrasion resistance 
C)  slight expansion 
D)  both A and C 
E)  both B and C

Question 20

Explain the differences between a study model, a cast, and a die. List the different types of materials associated with each.

Accepted Answer

Study models are used to observe the pat

Which of the following statements is true of the compressive strengths of gypsum materials?

Which use of gypsum is hardness and abrasion resistance especially important for?

How should gypsum powder and water be added to the mixing bowl?

The __ and dense the crystal of the hemihydrate, the less excess water required to get a workable mass.

Which form of dental gypsum product is created by boiling gypsum in a 30% solution of calcium chloride?

If the mixing water temperature ___________ the hemihydrate will not set.

Which of the following types of dental stones and dental plasters requires the least amount of excess water?

Which of the following is not a method for pouring a gypsum model base?

Accelerators are chemicals that the rate of setting and the time of setting.

Which of the following materials will accelerate the setting reaction of gypsum products?

Which of the following statements is true regarding disinfection of a gypsum model?

The impression should not be removed from the gypsum for _______ minutes.

Which statement(s) is (are) correct about making models, casts, and dies?

Which statement is correct regarding epoxy dies?

When a model or die is wet, its compressive and tensile strength is approximately ____________ its strength when dry.

Which of the following chemicals is an effective accelerator for gypsum materials?

Epoxy materials are compatible with most of the elastomeric impression materials. Epoxy materials can be used with alginates.

Which of the following statements is true of the handling of an alginate impression?

Gypsum model and die materials exhibit ________ in contrast to epoxy model and die materials.

Explain the differences between a study model, a cast, and a die. List the different types of materials associated with each.

Introduction to Restorative Dental Materials

Properties of Materials

Preventive Dental Materials

Direct Esthetic Restorative Materials

Dental Amalgam

Finishing, Polishing, and Cleansing Materials

Cements

Impression Materials

Waxes

Casting Alloys, Wrought Alloys, and Solders

Casting, Soldering, and Welding

Polymers in Prosthodontics

Dental Ceramics

Dental Implants

Filters

Exam 9: Model and Die Materials

Which of the following statements is true of the compressive strengths of gypsum materials?

Which use of gypsum is hardness and abrasion resistance especially important for?

How should gypsum powder and water be added to the mixing bowl?

The ________ and ______ dense the crystal of the hemihydrate, the less excess water required to get a workable mass.

Which form of dental gypsum product is created by boiling gypsum in a 30% solution of calcium chloride?

If the mixing water temperature ___________ the hemihydrate will not set.

Which of the following types of dental stones and dental plasters requires the least amount of excess water?

Which of the following is not a method for pouring a gypsum model base?

Accelerators are chemicals that ________ the rate of setting and ________ the time of setting.

Which of the following materials will accelerate the setting reaction of gypsum products?

Which of the following statements is true regarding disinfection of a gypsum model?

The impression should not be removed from the gypsum for _______ minutes.

Which statement(s) is (are) correct about making models, casts, and dies?

Which statement is correct regarding epoxy dies?

When a model or die is wet, its compressive and tensile strength is approximately ____________ its strength when dry.

Which of the following chemicals is an effective accelerator for gypsum materials?

Epoxy materials are compatible with most of the elastomeric impression materials. Epoxy materials can be used with alginates.

Which of the following statements is true of the handling of an alginate impression?

Gypsum model and die materials exhibit ________ in contrast to epoxy model and die materials.

Explain the differences between a study model, a cast, and a die. List the different types of materials associated with each.

Introduction to Restorative Dental Materials

Properties of Materials

Preventive Dental Materials

Direct Esthetic Restorative Materials

Dental Amalgam

Finishing, Polishing, and Cleansing Materials

Cements

Impression Materials

Waxes

Casting Alloys, Wrought Alloys, and Solders

Casting, Soldering, and Welding

Polymers in Prosthodontics

Dental Ceramics

Dental Implants

Filters

The __ and dense the crystal of the hemihydrate, the less excess water required to get a workable mass.

Accelerators are chemicals that the rate of setting and the time of setting.