481. Porcelain denture teeth________________?
A. Have a higher coefficient of thermal expansion than acrylic teeth:
B. Have a lower abrasion resistance than enamel
C. Should be used where the inter dental clearance is small
D. Have a higher abrasion resistance than gold
482. Glass ionomer cements are composed of______________?
A. Alumino silicate powder and phosphoric acid
B. Aluminosillicate powder and polyacrylate
C. Zinc oxide powder and phosphoric acid
D. Zinc oxide powder and polyacrylate liquid
483. Minimum thickness for type I zinc phosphate cement should be_______________?
A. 15 microns
B. 25 microns
C. 50 microns
D. 100 microns
484. Which of the following is common to both zinc eugenol cement and polycarboxylate cement?
A. Polyacrylic acid is liquid
B. Chemical bond to tooth structure
D. Substitution o eugenol by EBA to increase strength of cement
485. The addition of which of the following can accelerate the setting time of zinc oxide cement_____________?
A. Zinc acetate
B. Barium sulphate
C. Zinc sulphate
D. Barium chloride
486. pH of fully set zinc phosphate______________?
487. Which of the following cements is most irritant to pulpal tissues ?
A. Zinc phosphate
C. Glass ionomer
488. PH of polycarboxylate liquid is____________?
489. When selection the colour of cement to use for cementing a porcelain jacket crown, the powder being tested is best mixed with______________?
A. Glycerin-water solution
B. Cement liquid
D. Only water
490. The setting of zinc phosphate may be retarded by ?
A. Increased in the ratio of powder to liquid
B. Diluting the liquid with water
C. Increase the addition of powder to liquid
D. Decrease the addition of powder to liquid