Deck 10: Casting Alloys, Solders, and Wrought Metal Alloys

Question 1

Which of the following is true concerning grain formation in dental casting alloys?

A) Large crystals produce more desirable properties in the metal alloy than small crystals do.
B) Iridium or ruthenium is added to gold-base alloys to keep the crystals from growing too large.
C) Reheating gold-based alloys will degrade the physical properties.
D) Reheating base-metal alloys will not degrade the physical properties.

Answer 1

Iridium or ruthenium is added to gold-base alloys to keep the crystals from growing too large.

Question 2

Which of the following is the most esthetic margin for a ceramic-metal crown?

A) Disappearing metal margin
B) Porcelain facial margin
C) All-metal margin
D) All-metal facing

Answer 2

Porcelain facial margin

Question 3

The higher the fineness number of a gold solder, the _______ the gold content and the ______ the melting point of the solder.

A) higher; higher
B) higher; lower
C) lower; higher
D) lower; lower

Answer 3

higher; lower

Question 4

Flux is used when gold castings are soldered, to:

A) lower the melting range of the solder
B) remove surface oxides so the solder will flow freely and wet the alloy surfaces as it melts
C) prevent uneven heating of the unit, causing the gold to crack
D) prevent greening of the gold casting

Question 5

Silver-based solders are used primarily in dentistry to:

A) join together units of a bridge
B) add contacts to a bridge
C) solder wire components to removable orthodontic appliances
D) create wires, brackets, and bands used in orthodontics

Question 6

After the substructure for a porcelain-bonded-to-metal crown is cast in metal, it is heated at high temperature to:

A) reduce the grain size
B) anneal the metal
C) form oxides on the surface of the metal
D) cause the metal to slump and adapt to the die

Question 7

Which of the following is a noble metal used for dental casting alloys?

A) Silver (Ag)
B) Platinum (Pt)
C) Copper (Cu)
D) Titanium (Ti)

Question 8

Which of the following is true of the preparation of the metal substructure for porcelain-bonded-to-metal crowns?

A) The metal substructure must be at least 1.5 mm thick.
B) The metal substructure must be concave in shape.
C) The metal substructure should have sharp angles.
D) To make room for the metal substructure and porcelain, these crowns require greater reduction of the tooth than all-metal crowns.

Question 9

Which of the following would not be considered an extracoronal restoration?

A) Inlay
B) Onlay
C) Crown

Question 10

Which of the following base metals has the highest incidence of allergic response?

A) Nickel
B) Chromium
C) Beryllium
D) Gallium

Question 11

Which of the following statements is true of noble dental casting alloys?

A) They must contain at least 60% by weight noble alloys, of which gold must account for at least 40% by weight.
B) They require gold and must contain at least 25% noble metals by weight.
C) They do not require any gold but must contain at least 25% noble metals by weight.
D) They do not require gold and require less than 25% by weight of noble metals.

Question 12

The metals in porcelain bonding alloys are selected and blended so they have which of the following properties?

A) They have the ability to withstand the low temperatures at which porcelain is fired without distorting or melting.
B) They have a higher thermal expansion than gold alloys used for all-metal crowns.
C) Small amounts of metals such as indium, iron, tin, or gallium are added to form oxides on the metal surface to which the porcelain will bond.
D) Titanium and titanium alloys are added for easy handling.

Question 13

Dental wrought wire is primarily used for:

A) wires, brackets, and bands used in orthodontics
B) clasps for removable prosthetic appliances
C) closing holes ground into the occlusal surface by adjusting the bite
D) correcting small marginal deficiencies on onlays and crowns

Question 14

Which of the following is true concerning the use of endodontic files and reamers in dentistry?

A) Stainless steel files become more flexible as the diameter of the file increases.
B) Nickel-titanium files are far more flexible than stainless steel files.
C) Reamers are similar to files except that they have more twists in the metal and cut faster.
D) Rotary instruments are usually composed of stainless steel alloys.

Question 15

Which of the following is true concerning endodontic posts?

A) Posts reinforce endodontically treated teeth against fracture.
B) A post is one type of dental implant.
C) Parallel posts have been shown to transmit less stress to the root than tapered posts.
D) Pre-formed posts generally are made with the core already attached.

Question 16

During conventional root canal therapy, the root canal space is sealed with _________ so that bacteria cannot grow in the space.

A) silver amalgam
B) zinc phosphate
C) gutta percha
D) chlorobutanol

Question 17

The arch wire is held to the orthodontic bracket by:

A) cement
B) ligature wire or elastics
C) magnets
D) capillary adhesion

Question 18

Palladium:

A) has poor corrosion resistance
B) increases the hardness of the alloy
C) is more expensive than gold
D) is a precious metal but it is not considered noble

Question 19

Which of the following is true concerning nickel allergy?

A) Men have a higher rate of allergy to nickel than do women, by a ratio of 10 to 1.
B) The overall allergy rate to nickel for the general population is about 1% to 3%.
C) It is more common to see nickel allergy in removable partial dentures than in the margins of base-metal crowns.
D) Some responses to nickel cause a skin reaction rather than a response in the mouth, even though the oral cavity is the source of the nickel.

Question 20

Which of the following metals is added to both gold and silver solders to lower the melting range?

A) Borax
B) Potassium fluoride
C) Tin
D) Indium

Question 21

An advantage of using a wrought metal is that it:

A) easily deforms
B) does not bend
C) can be heated
D) uses light force

Question 22

Silver solders are used for:

A) soldering orthodontic wires
B) soldering crowns and pontics
C) soldering partial denture clasps

Question 23

Match the items with the correct description below.
Noble alloy

A)Alloy composed of non-noble metals
B)A mixture of two or more metals
C)Alloy containing at least 60% noble metals, 40% of which must be gold
D)Classification of metal based on its high cost
E)Alloy composed of metals that do not corrode readily

Question 24

Flux is used with solder to:

A) increase adhesion
B) prevent cracking
C) remove oxidation
D) reduce solder flow

Question 25

Why would zinc be added to a base-metal mixture?

A) Makes it stronger
B) Reduces oxidation
C) Decreases solubility
D) Provides luster

Question 26

Match the items with the correct description below.
Base-metal alloy

A)Alloy composed of non-noble metals
B)A mixture of two or more metals
C)Alloy containing at least 60% noble metals, 40% of which must be gold
D)Classification of metal based on its high cost
E)Alloy composed of metals that do not corrode readily

Question 27

Of the following, which is the base metal?

A) Palladium
B) Gold
C) Platinum
D) Gallium

Question 28

The primary purpose of the endodontic post is to:

A) retain the core buildup
B) reinforce the tooth
C) bond with the crown
D) fill the access for strength

Question 29

Match the items with the correct description below.
High-noble alloy

A)Alloy composed of non-noble metals
B)A mixture of two or more metals
C)Alloy containing at least 60% noble metals, 40% of which must be gold
D)Classification of metal based on its high cost
E)Alloy composed of metals that do not corrode readily

Question 30

Match the items with the correct description below.
Precious metal

A)Alloy composed of non-noble metals
B)A mixture of two or more metals
C)Alloy containing at least 60% noble metals, 40% of which must be gold
D)Classification of metal based on its high cost
E)Alloy composed of metals that do not corrode readily

Question 31

Match the items with the correct description below.
Alloy

A)Alloy composed of non-noble metals
B)A mixture of two or more metals
C)Alloy containing at least 60% noble metals, 40% of which must be gold
D)Classification of metal based on its high cost
E)Alloy composed of metals that do not corrode readily

Question 32

Tin is added to solders used in dentistry to:

A) strengthen the bond
B) lower the melting point
C) improve flow
D) reduce oxidation

Question 33

Patients who have an adverse reaction to base-metal appliances such as partial dentures are typically allergic to:

A) chrome
B) cobalt
C) nickel
D) titanium

Question 34

Describe the different kinds of posts that are available.