Exam 11: Casting Alloys, Wrought Alloys, and Solders

A) all of the alloy melts
B) an alloy begins to melt
C) all of the alloy freezes upon cooling
D) some of the alloy freezes upon cooling

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A) Silver
B) Cobalt
C) Chromium
D) Aluminum

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A) Silver will not corrode in the oral environment.
B) The term precious metal is preferred over noble metal.
C) Seven noble metals are commonly used in dental casting alloys.
D) Base metals are required in dental alloys for strength, flexibility, and wear resistance.
E) Base metals are viewed in dentistry as bad metals and are not used in dental restorations.

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A) Forms a surface oxide layer to bond to
B) Smooth surface to prevent irregularities in the ceramic
C) Decreases the thickness to allow for more ceramic build-up
D) Lowers the solidus of the metal so it is compatible with the ceramic temperatures

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A) The solidus of the alloy must be lower than the fusion temperature of the ceramic.
B) The solidus of the alloy must be higher than the fusion temperature of the ceramic.
C) The coefficient of thermal expansion for the alloy should be less than that of the ceramic.
D) Both A and C
E) Both B and C

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A) tin
B) nickel
C) copper
D) titanium

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A

A) The ability to be mechanically formed
B) The ability to be drawn into a wire
C) Corrosion resistance
D) Tarnish resistance

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A) gradations
B) granules
C) lattice
D) grains

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A) dark gray; dark yellow
B) light yellow; light gray
C) light yellow; dark gray
D) dark gray; light yellow

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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.

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Dental casting alloys (versus wrought alloys) are alloys used clinically in their as-cast form. In dentistry, casting alloys are categorized in several ways but most often on the basis of noble metal content. The nobility of an alloy is expressed as a sum of the weight percentages of the noble metals in the alloy. For example, if an alloy contains 60% gold, 10% palladium, 5% platinum, and 25% copper, the nobility would be 75% (the sum of gold, palladium, and platinum). Alloys also are described on the basis of their most common metal. For example, an alloy with 75% gold often is described as gold based, or an alloy with 60% nickel may be described as nickel based. The term based indicates which metal is the major component in the alloy and should not be confused with the term base metal. There are three major organizations worldwide. The ADA is the entity of choice in the United States.

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.

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A) Bond direct composite to the metal substructure.
B) Refire new porcelain to the metal while the crown remains in the mouth.
C) Remove the crown, refire new porcelain to the metal, and then re-cement the crown.
D) Prevent debonding by selection of compatible alloys and ceramics and the proper manipulation of these materials during fabrication.

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A) Select an appropriate alloy.
B) Periodic cleaning of the ceramic oven
C) Firing the restoration at the appropriate temperature
D) A, B, and C
E) Only A and C are correct.

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A) Its relatively high melting point
B) Its resistance to corrosion
C) Its yellow color
D) A, B, and C
E) A and C

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A) flow
B) liquidus
C) solidus
D) viscosity

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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.

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A

A) Zinc
B) Nickel
C) Copper
D) Titanium
E) Palladium

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