1051. Gold based metal ceramic alloys are best cast Lg which of the following?
A. Gypsum investment .
B. Phosphate bonded investment with carbon. *
C. Phosphate bonded investment without carbon.
D. Silica bonded.
E. Silica bonded investment with cashon.
1052. Regarding base metal alloys:
A.The casting shrinkage of base metal alloys is less than that of gold alloys.
B. Chromium added to base metal alloy acts as a solid solution hardner. *
C. Carbide precipitation to a certain extent decreases strength of
D. Manganese and silicone are added to base metal alloys to act as accelerator.
E. Cobalt act to provide flexibility to base metal alloy.
1053. Hardness of which of the following abrasives is maximum?
C. Boron carbide *
D. Silicone carbide
1054. Regarding dental implant materials?
A. Titanium substructure is coated with tricalcium phosphate to act as disinfectant.
B. Ceramics are used as implant materials because of their aesthetics.
C. Co-Cr alloys (63% with other metals is- often used due to
their outstanding strength.
D. Commercially pure titanium should not be used as it can cause corrosion in vivo.
E. Calcium hydroxyapetite crystals are bonded to titanium for better adhesion to bone. *
1055. Which of the following gases used for soldering purposes has the highest temperature?
B. Natural gas.
C. Acetylene . *
E. Carbon oxide.
1056. What must be added to steel in order to render it ‘stainless’?
A. Chromium 12-30% *
B. Carbon less than 1.2%
C. Chromium oxide 3-20%
D. Flouride 2-3%