871. Glass ionomer cements are primarily used for?
A. temporary restorations
B. restoring eroded areas
C. pulp capping
D. thermal insulating bases
872. The chief ingredient of an irreversible hydrocoiloid impression material is?
A. sodium alginate
B. potassium oxalate
D. calcium sulfate
E. zinc oxide
873. Methyl methacrytateresins are used for all of the following, except?
A. for the manulacture of teeth
B. as impression materials
C. for constructing impression trays
D. as filling materials
E. none of the above
874. Gold casting alloys can be age hardened by heating at?
A. 500°C for 10 min followed by slow cooling to room temperature
B. 300°C for 1 hour followed by slow cooling to room temperature
C. 750-900°C for 5-10 min and then quenching in water
D. 200-450°C for 15-30 min and then quenching in water
875. When die spacers are used, the gypsum die Is coated with resin?
A. only on the enamel surfaces
B. to within 0.5 mm of the margin
C. Upto 1.0mm cervical to the gingival finiish line
D. onto the exposed portion of the tooth on the die
876. Which of the following components of alginate impression material may be a possible healthhazard?
A. Alginic acid
B. Triethanol amine
E. None of the above
877. Butyl rubber dissolved in chloroform is used as a tray adhesive, when making an impression with
A. agar hydrocolloids
B. addition silicones
D. condensation silicones
878. Pyroplastic flow of dental porcelain?
A. will be high if the soda/potash ratio is less
B. is determined by the soda form of feldspar
C. is determined by the potash form of feldspar
D. is determined by the quartz form
E. should be high
879. When cristobalite is heated to 300°C, it?
A. exhibits slight shrinkage
B. changes from beta to alpha form
C. decreases in density
D. inverts from a high form to a low form
880. The sol to gel transformation in the case of reversible hydrocolloids, is a function of ?
B. water content
C. potassium sulfate concentration
D. silica content