1021. The dental amalgam alloys and mercury are mixed in ratio of:

A. 1:1 *
B. 2:1
C. 1:2
D. 1:3
E. 1:4

1022. Most common drawback of amalgam restoration is:

A. Secondary expansion.
B. Porosity.
C. Marginal break-down.*
D. Contraction on setting.
E. Contraction away from margins.

1023. What are the consequences of prolonged heating of a dental casting investment?

A. Disintegration of the investment.
B. Rough moulds of investment.
C. Contamination of the alloys.
D. Any of the above. *
E. Expansion of alloys .

1024. Regarding dental Amalgam:

A. It is a mixture of silver alloy and mercury. *
B. It is be composed of spherical tin and mercury.
C. It is a mixture of irregular particles of silver and tin.
D. Amalgamation process is formed during heating of silver-mercury.
E. The process of mixing amalgam is called Amalgamation.

1025. Which part of an amalgam restoration has the highest mercury concentration?

A. Marginal area. *
B. Centre of the restoration.
C. Pulpal area.
D. Proximal surface of restoration.
E. Inclined plane.

1026. What is the maximum level of occupational exposure considered safe with regard to mercury vapors?

A. 5 mg of mercury
B. 50 mg *
C. 35 mg
D. 25 mg
E. 1 mg of mercury

1027. The cement which has antibacterial property is:

A. Copper oxide cement. *
B. Glass informer cement.
C. Polycarboxylate cement.
D. Zinc phosphate cement .
E. Zinc oxide Eugenol cement.

1028. Cement extensively used for attachment of orthodontic brackets to teeth is.

A. Silicate cement.
B. Resin cement. *
C. Glass ionomer cement.
D. Copper oxide cement.
E. ZnO Eugenol cement.

1029. Cement not irritant to pulpal tissue is.

A. Calcium hydroxide cement. *
B. Silicate cement.
C. Copper cement.
D. Glass ionomer cement.
E. Resins cement.

1030. The main resin constituent of polishable composite resin is:

A. Polymethymethacrylae
B. Polycarbonate
C. Cyanoacrylate
D. Urethane *
E. Dimethacrylate.