Question 1

Expansion of the binder from added water to the investment is called ________ expansion.

Accepted Answer

A)  hygroscopic 
B)  chemical 
C)  burnout 
D)  thermal

Question 2

The total expansion of the investment is the sum of the hygroscopic and thermal expansions. Investments rely primarily on hygroscopic expansion to compensate for casting shrinkage of the metal.

Accepted Answer

A)  The first statement is correct; the second statement is correct. 
B)  The first statement is correct; the second statement is incorrect. 
C)  The first statement is incorrect; the second statement is correct. 
D)  The first statement is incorrect; the second statement is incorrect.

Question 3

Which of the following is correct about phosphate-bonded investments?

Accepted Answer

A)  Use a silica refractory 
B)  Use a gypsum investment binder 
C)  Are used for ceramic-alloy restorations 
D)  Both A and C 
E)  Both B and C

Question 4

Which statements are correct regarding the pickling of a casting?

Accepted Answer

A)  Uses hot calcium carbonate 
B)  Removes surface oxides 
C)  Uses hot sulfuric acid 
D)  A and B 
E)  B and C

Question 5

A casting alloy is heated in a _________ made of heat-resistant ceramic.

Accepted Answer

A)  burnout oven 
B)  casting ring 
C)  sprue base 
D)  crucible

Question 6

The temperature in a burnout oven is commonly _____ for high noble alloys.

Accepted Answer

A)  100° C 
B)  100° F 
C)  500° C 
D)  500° F

Question 7

Which of the following statements is(are) true of sprues?

Accepted Answer

A)  Sprues may be made of wax, plastic, or metal. 
B)  Sprues are placed on cusps of the wax pattern. 
C)  Sprues are placed in the central groove of the wax pattern. 
D)  A and B are true statements. 
E)  A and C are true statements.

Question 8

Which of the following statements is(are) true concerning expansion of an investment material?

Accepted Answer

A)  Expansion of the investment from added water is called hydroscopic expansion. 
B)  Investments are designed to expand to compensate for casting shrinkage. 
C)  Expansion of the investment from heat is called thermal expansion. 
D)  A, B, and C are true statements. 
E)  B and C are true statements.

Question 9

Which of the following statements is true of investments used for casting?

Accepted Answer

A)  The refractory material in most dental investments is a form of calcium. 
B)  The binder and the refractory material contribute to expansion of the investment. 
C)  The binder and the refractory material contribute to contraction of the investment. 
D)  The binder, but not the refractory material, contributes to expansion of the investment. 
E)  The refractory material, but not the binder, contributes to expansion of the investment.

Question 10

Which of the following sequences describing the steps involved in making a dental casting from start to finish is correct?

Accepted Answer

A)  Burnout, casting, making the wax pattern, spruing the pattern, investing, removal of investment, pickling, and finishing 
B)  Making the wax pattern, burnout, casting, spruing the pattern, investing, removal of investment, pickling, and finishing 
C)  Making the wax pattern, spruing the pattern, burnout, casting, investing, removal of investment, pickling, and finishing 
D)  Making the wax pattern, spruing the pattern, investing, burnout, casting, removal of investment, pickling, and finishing

Question 11

What method is used to inject the molten alloy into the casting ring?

Accepted Answer

A)  Slip casting 
B)  Press molding 
C)  Linear casting machine 
D)  Centrifugal casting machine

Question 12

What is the purpose of a casting ring?

Accepted Answer

A)  Retains the investment while it sets 
B)  Is commonly lined with a dry ceramic-paper liner 
C)  Is commonly lined with a wet ceramic-paper liner 
D)  Both A and B 
E)  Both A and C

Question 13

The sprue is removed with a thin _____ disk.

Accepted Answer

A)  cuttle 
B)  carbide 
C)  diamond 
D)  carborundum

Question 14

Approximately how long does it take for the wax to burn out in the kiln?

Accepted Answer

A)  30 minutes 
B)  1 hour 
C)  1.5 hours 
D)  2 hours

Question 15

The investment material is _________; the wax pattern is __________.

Accepted Answer

A)  hydrophilic; hydrophilic 
B)  hydrophilic; hydrophobic 
C)  hydrophobic; hydrophilic 
D)  hydrophobic; hydrophobic

Question 16

An invested wax pattern should set for at least ________ before burnout.

Accepted Answer

A)  10 minutes 
B)  45 minutes 
C)  12 hours 
D)  24 hours 
E)  1 week

Question 17

What is the purpose of the sprue?

Accepted Answer

A)  Provides access channel for molten alloy to reach casting 
B)  Form the occlusal surface of a casting 
C)  Form the proximal surface of a casting 
D)  Reduce the metal content of a casting

Question 18

Compare and contrast casting with milling.

Accepted Answer

The answer of Compare and contrast casting with milling....

Question 19

Following removal of a ring from the burnout oven, any delay in casting of more than ___________ will severely compromise the fit and quality of the cast restoration.

Accepted Answer

A)  1 to 2 seconds 
B)  8 to 10 seconds 
C)  20 to 30 seconds 
D)  60 to 90 seconds 
E)  2 to 3 minutes

Question 20

During the casting process, how is a metal sprue treated?

Accepted Answer

A)  Coated with a surfactant 
B)  Removed before casting 
C)  Burned out with the wax 
D)  Secured in the investment

Exam 12: Casting, Soldering, and Welding