A. Decreasing the sprue length
B. Decreasing the sprue thickness
C. Increasing the melting temperature
D. Increasing the mould temperature
Related Mcqs:
- 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 - Porosity in porcelain can be prevented by_______________?
A. Thoroughness of condensation
B. Rapidity of firing
C. High firing temperature
D. All of the above - The lingual surface of epiglottis is lined by_______________?
A. Stratified squamous epithelium
B. Simple squamous epithelium
C. Stratified columnar epithelium
D. Pseudostratified epithelium - 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 - 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 - Suck back porosity is due to_________________?
A. Attached impurities on undersurface of casting
B. Hot spot
C. No rapid cooling
D. Inadequate melting temperature - Localised shrinkage porosity is seen when there________________?
A. Thin sprue
B. No reservoir
C. Investment heated strongly
D. Inadequate air discharge - 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 - 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 - 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
