1. the prinicipal factor in minimising the firing shrinkage of porcelain is the uniformity of particle size thoroughness of condensation fusion temperature ratio of flux to feldspar 2. Etching of feldspathic ceramic: HN03 35% Phosphoric acid HCL HF acid 3. the union of metal to porcelain fused restoration is by mechanically rough surface nickel and orcelain cobalt and porcelain tin and indium oxides 4. direct wax pattern may distort due to methoc of heating of wax release of internal stresses composition of wax the placement of reservior 5. Principle hardener in gold alloy is Zinc Palladium Copper Silver 6. Purpose of reservior is to Prevent removal of molten metal Gives smooth polished surface Prevent localised shrinkage porosity Help in removal of wax 7. a thinner mix of gypsum bondeded investment will result in increases setting expansion produce a smoother casting decrease setting expansion increases thermal expansion 8. when force is applied perpendicular to the metal surface,resultant deformation is compressive strain tensile strain shearing stress tensile stress 9. Structural durability is a? Structural phenomenon Mechanical phenomenon None of the above Biological phenomenon 10. Copper content of single composition alloys 9-20% 30-40% 13-30% 0-6% 11. what filler is used in impression compound “alginate” sodium bicarbonate calcium alginate diatomaceous earth sodium phosphate 12. Fins and spines in casting are caused by: Rapid heating of investment Water film present Increased casting pressure Prolonged heating 13. condensation shrinkage during porcelain firing is determined by uniform distriution of particle size rate of firing size and shape of particle type of investment used 14. In orthodontic stainless steel wire, content of carbon is 0.6 -0.8 percent 12-20 percent 1-1.2 percent 6-8 percent 15. In metal-ceramic restorations, failure or fracture usually occurs: in the porcelain in the metal None of the above at the porcelain-metal interface 16. Which of the following best describes “strain hardening” or “work hardening”? softening a metal at room temperature hardening (or deformation) of a metal at a very high temperature softening a metal by controlled heating and cooling hardening (or deformation) of a metal at room temperature 17. methyl methacrylate can be activated by all of the following except heat sulfuric acid derivatives lead peroxide tertiary amines 18. All of the following statements are true regarding glass ionomer restorations,except glass ionomers are somewhat esthetic and polish much better than composites glass ionomer adheres to mineralized tooth tissue glass ionomer is often the ideal material of choice for restoring root surface caries in patients with high caries activity the best surface finish for a glass ionomer restoration is that obtained against a surface matrix 19. The dentist can best control the setting time of irreversible hydrocolloid impression material by altering the Mixing time Water temperature Amount of retarder added Water powder ratio 20. best cement for cementation of orthodontic molar bands silicate zinc phosphate GIC silicophosphate Loading … Question 1 of 20
