Chapter 10: Dental Amalgam

Chapter 10: Dental Amalgam

 

Complete Chapter Questions With Answers

 

Sample Questions Are Posted Below

 

MULTIPLE CHOICE

 

1. For what reason have insurance carriers seen a reduction in the use of dental amalgam for posterior restorations by approximately 45% in the past 20 years?

a.	Other direct restorative materials have superior durability, ease of handling, and physical characteristics.
b.	Its wear resistance and compressive strength are inferior to composite resin and glass ionomer cement.
c.	A study conducted by the National Institutes of Health (NIH) in 1991-1993 concluded that amalgam is not safe for human use.
d.	Concerns by patients about its safety and its lack of esthetics have prompted many patients to request tooth-colored materials.

 

 

ANS:  D

Insurance carriers have seen a reduction in the use of dental amalgam for posterior restorations by approximately 45% in the past 20 years, probably because concerns by patients about its safety and its lack of esthetics have prompted many patients to request tooth-colored materials. Still, no other direct restorative material has the durability, ease of handling, and good physical characteristics of amalgam. Its wear resistance and compressive strength are superior to composite resin and glass ionomer cement. A study conducted by the National Institutes of Health (NIH) in 1991-1993 concluded that amalgam is safe for human use.

 

REF:   p. 150             TOP:   Dental Amalgam

 

2. When the silver-based alloy used to create dental amalgam is mixed with _____, the reaction that occurs is called amalgamation.

a.	methyl methacrylate
b.	a bonding agent
c.	an acid etchant
d.	mercury

 

 

ANS:  D

When the silver-based alloy used to create dental amalgam is mixed with mercury, the reaction that occurs is called amalgamation. The material that is produced is called dental amalgam.

 

REF:   p. 150             TOP:   Dental Amalgam (Alloy Used in Dental Amalgam)

 

3. Modern dental amalgams are considered to be high in _____ content compared with their predecessors.

a.	copper
b.	silver
c.	zinc
d.	tin

 

 

ANS:  A

Modern dental amalgams are considered to be high in copper content (13% to 30%) compared with their predecessors, which had 2% to 4% copper by weight. They generally contain 40% to 70% silver and 12% to 30% tin. They are mixed with mercury 43% to 50% by weight.

 

REF:   p. 151             TOP:   Dental Amalgam (Composition)

 

4. Spherical alloys require _____ mercury to wet the particles and generally set _____ than lathe-cut particles.

a.	more; more quickly
b.	more; more slowly
c.	less; more quickly
d.	less; more slowly

 

 

ANS:  C

Spherical alloys require less mercury to wet the particles and generally set more quickly than lathe-cut particles.

 

REF:   p. 151             TOP:   Dental Amalgam (Composition)

 

5. In the low-copper amalgams, zinc was responsible for the gradual _____ of the amalgam over time if moisture contamination was present during placement.

a.	tarnish
b.	corrosion
c.	expansion
d.	contraction

 

 

ANS:  C

In the low-copper amalgams, zinc was responsible for the gradual expansion of the amalgam over time if moisture contamination was present during placement. Contact of the moisture with zinc caused the formation of hydrogen gas within the amalgam, which caused it to expand. Delayed expansion could cause the restoration to expand beyond the cavity walls and could cause cracking in the adjacent enamel.

 

REF:   p. 151             TOP:   Dental Amalgam (Composition)