Deck 11: Casting Metals, solders, and Wrought Metal Alloys

Question 1

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

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

Answer 1

gutta percha

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

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

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

Answer 3

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

Question 4

Dental wrought wire is primarily used for what purpose?

A) Clasps for removable prosthetic appliances
B) Wires,brackets,and bands used in orthodontics
C) Correcting small marginal deficiencies on onlays and crowns
D) Closing holes ground into the occlusal surface by adjusting the bite

Question 5

Why are silver-based solders used primarily in dentistry?

A) Add contacts to a bridge
B) Join together units of a bridge
C) Create wires,brackets,and bands used in orthodontics
D) Solder wire components to removable orthodontic appliances

Question 6

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

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

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

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

Question 9

How is the arch wire held to the orthodontic bracket?

A) Cement
B) Magnets
C) Capillary adhesion
D) Ligature wire or elastics

Question 10

Which description is correct regarding palladium?

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

Question 11

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

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

Question 12

Which of the following is true concerning endodontic posts?

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

Question 13

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

A) 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.
B) They have the ability to withstand the low temperatures at which porcelain is fired without distorting or melting.
C) They have a higher thermal expansion than gold alloys used for all-metal crowns.
D) Titanium and titanium alloys are added for easy handling.

Question 14

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

A) Anneal the metal
B) Reduce the grain size
C) Form oxides on the surface of the metal
D) Cause the metal to slump and adapt to the die

Question 15

Which of the following represents the correct order for application of the porcelain layers during the creation of a porcelain-bonded-to-metal crown?
1)Incisal porcelain
2)Opaque porcelain
3)Body porcelain

A) 1,2,3
B) 1,3,2
C) 2,3,1
D) 2,1,3

Question 16

Why is flux used when gold castings are soldered?

A) Prevent greening of the gold casting
B) Lower the melting range of the solder
C) Remove surface oxides so that the solder will flow freely
D) Prevent uneven heating of the unit,causing the gold to crack

Question 17

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 18

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

Question 19

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

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

Question 20

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

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

Question 21

Why is tin added to solders used in dentistry?

A) Improve flow
B) Reduce oxidation
C) Strengthen the bond
D) Lower the melting point

Question 22

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 23

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 24

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 25

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 26

Identify the wrought metals used for orthodontic wires.

Question 27

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

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

Question 28

What is an advantage of using a wrought metal?

A) Easily deforms
B) Does not bend
C) Can be heated
D) Uses light force

Question 29

Of the following,which is the base metal?

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

Question 30

What is the primary purpose of the endodontic post?

A) Reinforce the tooth
B) Bond with the crown
C) Retain the core buildup
D) Fill the access for strength

Question 31

Why is flux used with solder?

A) Increase adhesion
B) Prevent cracking
C) Remove oxidation
D) Reduce solder flow

Question 32

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

A) Chrome
B) Cobalt
C) Nickel
D) Titanium

Question 33

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

A) Inlay
B) Onlay
C) Crown

Question 34

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 35

What are silver solders used for?

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