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.Management Sciences
Category: Dental Materials
The modulus of elasticity is defined as_______________?
A. The stress at the proportional limit
B. The strain at the proportional limit
C. The stress/strain ratio within the proportional limit
D. None of the above
During setting of alginate impression materials________________?
A. Trisodium phosphate reacts with sodium alginate
B. Trisodium phosphate reacts with calcium sulphate
C. Colloidal changes to sol
D. Material in contact with soft tissues sets last
What is the minimum thickness of the elastomeric impression material for an accurate impression_______________?
A. 2 mm
B. 2-4 mm
C. Greater than 3 mm
D. Maximum in the area of operation
Powdered gold is___________________?
A. Made by a combination of chemical precipitation and atomization
B. Made by electrolytic precipitation
C. Made by beating pure gold at high temperatures
D. Made by milling pure gold ingots
The best way to remove a hydrocolloid impression from the patient’s mouth is____________?
A. Slight rocking of the impression to disengage it from the undercut
B. Wetting the periphery of the impression with moist cotton to break the peripheral seal
C. Sudden jerking of the impression to prevent tearing
D. Supporting the impression along with the tray to prevent disengaging of the tray alone
Over-trituration of silver alloy and mercury_______________?
A. Reduces contraction
B. Increases the strength of lathe cut alloy but reduces the strength of spherical alloy amalgam
C. Decreases creep
D. Gives al dull and crumbly amalgam
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
Polymerisation of heat-cured methyl methacrylate is initiated by______________?
A. Tertiary amine
B. Benzoyl peroxide free radical
C. Hydroquinone
D. Methyl ether
Rough surface of elastomeric impression results from_______________?
A. Inadequate mixing
B. Air bubbles
C. Too rapid polymerization
D. Incomplete polymerization caused by premature removal from mouth
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