Sub surface porosity can be decreased by_______________?

Related Mcqs:

1. In processing methyl methacrylate, the resin may show porosity if the flask is placed too soon porosity most likely occur_____________?

   A. Throughout the denture
   B. Near the borders
   C. In the thickest part
   D. On the denture surface

2. Porosity in porcelain can be prevented by_______________?

   A. Thoroughness of condensation
   B. Rapidity of firing
   C. High firing temperature
   D. All of the above

3. The lingual surface of epiglottis is lined by_______________?

   A. Stratified squamous epithelium
   B. Simple squamous epithelium
   C. Stratified columnar epithelium
   D. Pseudostratified epithelium

4. The porosity formed due to simultaneous nucleation of solid grains and gas bubbles at the first moment that metal freezes at the mold walls is called__________?

   A. Pinhole porosity
   B. Gas inclusion porosity
   C. Micro porosity
   D. Subsurface porosity

5. Suck back porosity in the casting can be eliminated by________________?

   A. Increasing the mould metal temperature difference
   B. Increasing the flow of molten metal
   C. Flaring the point of the sprue attachment
   D. All of the above

6. Suck back porosity is due to_________________?

   A. Attached impurities on undersurface of casting
   B. Hot spot
   C. No rapid cooling
   D. Inadequate melting temperature

7. Localised shrinkage porosity is seen when there________________?

   A. Thin sprue
   B. No reservoir
   C. Investment heated strongly
   D. Inadequate air discharge

8. Back pressure porosity can be avoided by________________?

   A. Using asbestos linear
   B. Placing the sprue at least one quarter inch away form the end of casting ring
   C. Preventing rapid heating the investment in burnout oven
   D. Using a short and wide sprue

9. Porosity of denture base is due to_______________?

   A. Packing at dough stage
   B. Curing at 160°F for 9 hrs
   C. Inadequate pressure
   D. All of the above

10. To prevent porosity in self-cure acrylic resin, curing should be carried in______________?

    A. Cold water
    B. Hot water
    C. Under tap water
    D. Under vacuum pressure