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.Management Sciences
Category: Dental Materials
When restoring a tooth with resin material, acid etching can do all of the following except______________?
A. Increase the surface area
B. Permit chemical bonding between resin and enamel
C. Create surface irregularities in enamel for better mechanical retention of resin
D. Condition the tooth surface for better wetting
The best pickling solution for gypsum bonded investment is_______________?
A. Hydrochloric acid
B. Nitric acid
C. Sulphuric acid
D. Phosphoric acid
Quartz is added to gypsum bonded investment to______________?
A. Increase the strength
B. Counter balance contraction of gypsum during heating
C. aid in hygroscopic expansion
D. Increase the shelf life of investment
When porcelain is basked against metal, it should possess a________________?
A. high fusion expansion
B. high fusion temperature
C. linear coefficient of thermal expansion less than but close to that of metal
D. Linear coefficient of thermal expansion greater than, but close to that of the metal
Macromolecules in Dental Resin is attached by______________?
A. Covalent bonds
B. sonic bonds
C. Vander Wall’s Forces
D. Hydrogen Bonds
A rough / Chalky surface of the cast is due to_______________?
A. Not waiting for 20 min before pouring
B. High speed accelerator
C. Air incorporation in the mix
D. All of the above
In amalgam alloy which acts as oxygen scavenger_____________?
A. Cu
B. Zn
C. Pd
D. Ag
Insufficient closure of the flasks during packing of denture base resin can result in_____________?
A. Poor colour stability
B. Less polymerization shrinkage
C. Increase in vertical dimension
D. Decrease in vertical dimension
Discolouration of silver alloy is due to_____________?
A. Tarnish
B. Tarnish and corrosion
C. Wet corrosion
D. Dry corrosion
All of the following statements are true for zinc oxide eugenol cements except______________?
A. Equal lengths of base paste and accelerator paste are mixed together until the mix has a uniform colour
B. Increase in temperature and humidity shorten the setting time
C. The mix appear thick at the start of mixing but after 30 seconds of additional spatulation it becomes more fluid
D. Water accelerates but heat retards the setting of zinc oxide eugenol cements
E. Both C & D
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