Back pressure porosity can be avoided 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. 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

3. Placing cast under tap water is to be avoided as______________?

   A. H2O interferes with hygroscopic expansion
   B. H2O inhibits polymerization of dental resin
   C. H2O interferes with Crystallization of dihydrate
   D. Gypsum is slightly soluble in water and the surface of the cast will be eroded

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 is due to_________________?

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

6. Sub surface porosity can be decreased by_______________?

   A. Decreasing the sprue length
   B. Decreasing the sprue thickness
   C. Increasing the melting temperature
   D. Increasing the mould temperature

7. Localised shrinkage porosity is seen when there________________?

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

8. Drug to be avoided in a patient allergic to penicillin is_____________?

   A. Sulphonamide
   B. Tetracycline
   C. Ampicillin
   D. Cholarmphenicol

9. Following analgesic combination should be avoided ?

   A. Aspirin and Codeine
   B. Paracetamol and Dextropropoxyphene
   C. Ibuprofen and Paracetamol
   D. Ibuprofen and DIclofenac

10. Aspirin is avoided in children with influenza infection because of association______________?

    A. Reye’s syndrome
    B. Nausea
    C. Diarrhoea
    D. Acid-base imbalance