dental materials MCQs – Page 23

Practise focused dental materials questions with marked answers for exam preparation and subject revision.

dental materials Mcqs
441. To prevent porosity in dental porcelain it should be backed________________?
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A. Under pressure

B. Boric oxide

C. In vacuum

D. For long period

442. Green strength with reference to plaster means_____________?
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A. The wet strength

B. Compressive strength

C. Strength of dental stone due to green colour

D. Dry strength

443. Quartz is Dental porcelain is______________?
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A. Crack minimzer

B. Strengthener

C. Binder

D. Pigment

444. All of the following statements are true for zinc oxide eugenol cements except______________?
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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
445. Which is not true about high copper amalgam alloys______________?
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A. Low creep

B. Low tensile and compressive strength

C. High tensile strength

D. Low Hg: Alloy ratio

446. Which of the following do polycarboxylate and GIC have in common ?
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A. Polyacrylic acid

B. Polysiloxane

C. Phosphoric acid

D. Ion leachable glass

447. The most toxic form of mercury is_________________?
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A. Methyl and ethyl mercury

B. Inorganic mercury forms

C. Mercury vapour

D. Mercury sulphide

448. Clogging of an abrasive wheel with debris causing reduction of abrasive action is called________________?
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A. Blinding

B. Truing

C. Buffing

D. Dressing

449. Opaque porcelain________________?
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A. Not used to mask the colour of the cement used in placing of restoration

B. Is Feldspathic glass

C. Used to produce the characteristic translucence, which is an inherent aspect of the incisal edge in natural teeth

D. Contains opacifier like zirconium and titanium oxide
450. Most preferable cement for temporary restoration______________?
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A. ZOE

B. Ca (OH)2

C. Zinc polycarboxylate cement

D. GIC

451. Porcelain denture teeth________________?
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A. Have a higher coefficient of thermal expansion than acrylic teeth:

B. Have a lower abrasion resistance than enamel

C. Have a higher abrasion resistance than gold

D. Should be used where the inter dental clearance is small

452. Mode of failure during dislodgement of prosthesis cemented with zinc poly carboxylate cement is usually seen at the_____________?
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A. Cement tooth interface

B. Fracture of tooth or prosthesis

C. Cement prosthesis interface

D. Cleavage through the cement layer

453. Which is not present in porcelain________________?
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A. Amorphous material

B. Calcium carbonate

C. Silica

D. Feldspar

454. Thermal conductivity of which material is close to dentin____________?
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A. Cavity varnish

B. Amalgam

C. Silicate

D. Composite resin

455. Which of the following is common to both zinc eugenol cement and polycarboxylate cement?
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A. Chemical bond to tooth structure

B. Polyacrylic acid is liquid

C. Chelation

D. Substitution o eugenol by EBA to increase strength of cement

456. The ADA specification No 1 for composition of amalgam alloy recommends______________?
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A. None of the above

B. 65% silver, 32% tin and 3% copper

C. 65% silver, 29% tin and 5-6% copper

D. 49% silver, 32% tin and 19% cooper

457. Which of the following is true about direct filling gold______________?
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A. Whatever may be the type voids are inherent

B. None of the above

C. Properly condensed mat gold has no voids

D. Voids can be avoided with manual condensation

458. Which phase provides maximum strength in hardened mercury/silver alloy ?
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A. Silver / Tin phase

B. Tin / Mercury phase

C. Silver / Mercury phase

D. Zinc / Mercury phase

459. What fraction of inhaled mercury vapors retained in the body ?
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A. 65-85%

B. 45-55%

C. More than 85%

D. 55-65%

460. Water powder ratio of dental stone and plaster is respectively_________________?
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A. 0.28 and 0.6

B. 0.6 and 3.2

C. 0.28 and 0.98

D. 0.6 and 0.28