581. Co-efficient of Thermal exansion of amalgam is______________?

A. 6.6 a (ppm k-1)
B. 11.4 a (ppm k-1)
C. 14.0 a (ppm k-1)
D. 25.0 a (ppm k-1)

582. A patient who has had a recent amalgam filling in the upper teeth has a gold filling in the lower teeth, the patient complains of pain. The reason for this can be mainly_____________?

A. Improper amalgam filling
B. Pulp exposure
C. Galvanism
D. None of the above

583. Outstanding clinical performance of dental amalgam restoration is related to its____________?

A. Compressive strength
B. Tensile strength
C. Corrosion
D. Creep

584. Absorption of mercury in the human body occurs least from_____________?

A. Lungs
B. Gastro-intestinal Track
C. Skin
D. Kidneys

585. Mercury is toxic because it_____________?

A. Complexes with hemoglobinto form methemoglobin
B. Inhibits hemoglobin synthesis, producing anemia
C. Inhibits anaerobic glycolysis
D. Binds to sulfhydryl groups

586. What fraction of inhaled mercury vapors retained in the body ?

A. 45-55%
B. 55-65%
C. 65-85%
D. More than 85%

587. The effect of trituration on strength in an amalgam restoration depends on______________?

A. Amalgam alloy
B. Trituration time
C. Speed of amalgamator
D. All of the above

588. Decrease in creep occurs in_______________?

A. Under trituration or over trituration of amalgam
B. Decreases with condensation pressure
C. Increase with condensation pressure
D. Cannot be predictable

589. Cavo surface angle for amalgam resoration is butt joint as____________?

A. It increases compresssive and tensile strengths
B. Decreased compressive, increased strength
C. Decreased compressive, decrease tensile strength
D. Increased compressive, increased tensile strength

590. Which of the following are characteristic feature of high copper amalgam alloy ?

A. Low compressive strength
B. High marginal breakdown
C. Less marginal 
D. High creep


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