MCQs on Dental Materials : Amalgams Part 1

The term "trituration" means:

A. Lysing amalgam alloy
B. Mixing of amalgam alloy and mercury
C. Removal of excess of mercury
D. None of the above

Dynamic creep is the:

A. Continuing alloying between Silver-Tin alloy and mercury during the life of the restoration
B. Deformation of set amalgam during function
C. Process whereby alloy is wetted by mercury
D. Spread of amalgam during packing

The highest mercury concentration in amalgam filling is found:

A. At the margin of restoration
B. In the centre of the restoration
C. In the deepest part of the restoration
D. None of the above

The dental amalgam is most resistant to:

A. Compressive stress
B. Impact stress
C. Shear stress
D. Tensile stress

The ADA specification no. 1 for composition of amalgam alloy recommends:

A. 65% silver, 32% tin and 3% copper
B. 49% silver, 32% tin and 19% copper
C. 65% silver, 29% tin and 5-6% copper
D. None of the above

According to ADA sp. no. 1, the minimum compressive strength for silver amalgam after one hour should be:

A. 80 Mpa
B. 140 Mpa
C. 260 Mpa
D. 510 Mpa

Which of the following phases of dental amalgam has minimum strength?

A. Gamma 1
B. Gamma 2
C. Gamma 3
D. Epsilon 1

Admixed high copper alloy powder contains:

A. 9-20% copper
B. 13-20% copper
C. 9-30% copper
D. 13-30% copper

Compared to conventional amalgams, spherical amalgams:

A. Require more mercury
B. Require heavy compaction forces
C. Have longer setting time
D. None of the above

Finishing and polishing of amalgam causes ___________ of the restoration.

A. Increase in tarnish and corrosion resistance
B. Increase in the marginal strength
C. Decrease the tarnish and corrosion resistance
D. Increase in the compressive strength

Which of the following statements about high copper silver alloy compared to conventional alloy is not true?

A. It has increased tensile and compressive strength
B. It has poor tarnish and corrosion resistance
C. Its edge strength is greater
D. Mercury content in the final restoration is less

Setting time of amalgam is best controlled by:

A. Using spherical particles
B. Lathe cut alloy
C. Altering Hg-alloy ratio
D. Trituration time

Increase in the residual mercury in silver amalgam filling can:

A. Cause fracture of the filling
B. Cause tarnish and corrosion
C. Increase in strength
D. Decrease condensation pressure

High Cu alloys have all of the following except:

A. High tensile strength
B. Low creep
C. High corrosion
D. None of the above

Chronic mercury toxicity results from:

A. Ingestion while removing old amalgam
B. Skin contact
C. Mercury vapor
D. All of the above

In non zinc containing dental amalgam alloy, the percentage of zinc present is:

A. Less than 0.02 %
B. Less than 0.1 %
C. Less than 0.01 %
D. None of the above

In spherical alloys as compared to lathe cut:

A. Less condensing force is required
B. More condensing force is required
C. Both require same condensing force
D. Manipulation is easy

High copper dental amalgams are superior to other amalgams because high copper dental amalgams:

A. have less marginal breakdown
B. are workable at lower Hg-alloy ratio
C. have a higher ratio of tensile to compressive strength
D. have less resistance to tarnish and corrosion

Well premeasured capsules of amalgam can release mercury vapor during:

A. Mulling
B. Carving
C. Condensation
D. Trituration

The largest component of amalgam alloy is:

A. Silver
B. Tin
C. Zinc
D. Copper

In a high copper amalgam, the phase which is eliminated is:

A. Gamma 1
B. Gamma 2
C. Gamma 1 and Gamma 2
D. No phase is eliminated

During amalgamation, trituration is done to:

A. dissolve the alloy in mercury
B. coat the alloy particles with mercury
C. remove excess mercury from amalgam
D. dissolve Hg in alloy

Moisture contamination of amalgam can lead to:

A. Marginal breakdown
B. Shrinkage
C. Delayed expansion
D. Increased stresses

Amalgam restorations give the best clinical service when the residual mercury content is:

A. 38-42%
B. 48-52%
C. 58-62%
D. 68-72%

Discoloration of silver alloy is due to:

A. Tarnish
B. Tarnish and corrosion
C. Wet corrosion
D. Dry corrosion

Percentage of tin in low copper alloy is:

A. 30-35%
B. 26-28%
C. 13-32%
D. 22-30%

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