1. titanium casting is done under vaccum in argon atmosphere under air pressure in nitrogen atmosphere in specifically fabricated aluminium vanadium crucibles using cad-cam technique 2. Any marked distortion of the casting is related to Distortion of the wax pattern Improper temperature control Suck back porosity Localised shrinkage 3. Hardening heat treatment for gold copper alloys involves Heating to 350 degree C for 15-30 min followed by quenching Quenching immediately after casting Quenching immediately after recrystallisation Heating to 700 degree C for 10 min followed by quenching 4. In orthodontic stainless steel wire which of the following is used to reduce hardness? Cobalt Carbon Silicone Chromium 5. an amalgam is an alloy one of whose consituent is silver one of those whose constituent is mercury of two or more metals of silver and tin 6. dental plaster powder and dental stone powder differ mainly in solubility shelf life particle porosity chemical formula 7. which zone of flame is used for melting alloys combustion zone central zone reducing zone oxidising zone 8. Porcelain is strongest when in a state of tension neutrality compression torsion 9. During final finishing of composite you find a void, what will you do: Re-etch and fill the composite Fill with composite after etching, application of bonding agent Leave as it is Remove entire composite and refill it 10. Mercaptan are a component of: Condensation silicone Addition silicone Polyether Polysulphide 11. setting time of zinc phospahte cement is retarted by increasing the rate of addition of powder to liquid decreasing the rate of addition of powder to liquid increasing the powder liquid ratio diluting the liquid with a small amount of water 12. strain hardening of a metal decreases its surface hardness resistance to corrosion strength proportional limit 13. Pinhole porosities are related to Distortion of wax pattern Casting investment junction Entrapement of gas during solidification Sprue casting dissociation 14. ductility means the metal can be transformed into sheets percentage elongation increases with rise in temperature subjecting a cylindrical specimen to a compressive load 15. gold alloys used for the fabrication of saddle bars and clasps are type IV type II type III type I 16. direct wax pattern may distort due to composition of wax methoc of heating of wax release of internal stresses the placement of reservior 17. Which of the following is a solid solution? gallium silver alloy amalgam silver palladium cobalt chromium 18. within practical limits when the water/powder ratio is increased beyond the recommended amount in mixing plaster the all of the above setting expansion is decreased compressive strength is decreased setting time is increased 19. the penetration of the fissure sealant into the fissures is independent of the chemical composition of the enamel must occur before the polymerisation of the material is not influenced by the wettability of the enamel is the result of a chemical bond between the sealant and enamel 20. Liquid which shows thickening on increasing strain is called Dilatant Newtonian Pseudoplastic Thixotropic Loading … Question 1 of 20
