dental materials Mcqs
601. Ag-Cu eutectic alloy has a characteristic Property of that fusion temp of_____________?
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A. The resultant alloy is greater

B. The resultant alloy varies according to the content of Ag of Cu

C. None of the above

D. The resultant alloy is lesser
602. Model plaster (white) used to cast study models before mixing with water, is largely composed of____________?
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A. CaCO3

B. (CaSO4)2-H2O

C. CaSO4-2H2O

D. CaO

603. The main purpose of adding metallic oxides in ceramic is________________?
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A. None of the above

B. Transparency

C. Colour matching

D. Opacity

604. Which of the following show chemical bond with enamel (Calcified tissues)______________?
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A. BIS-GMA resins in pit and fissure sealants

B. Composites

C. Polycarboxylate cements

D. Direct filling resins

605. Dental porcelains are crystalline materials of________________?
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A. Plastic

B. Rubber

C. Organic substances

D. Glass
606. Amalgam restorations give the best clinical service when the residual mercury content is_______________?
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A. 48-52%

B. 68-72%

C. 38-42%

D. 58-62%

607. Advantage of zinc containing amalgam is_______________?
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A. Resistance to creep

B. Better handling property

C. Toxicity to pulp and dentin

D. Dimensional Stability

608. A patient who has had a recent amalgam filling in the upper teeth has a gold filling in the lower teeth, the patient complains of pain. The reason for this can be mainly_____________?
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A. Improper amalgam filling

B. Pulp exposure

C. None of the above

D. Galvanism
609. What is common in amalgam and ceramics ?
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A. Less compressive strength and tensile strength

B. More compressive strength but less tensile strength

C. Less compressive strength but more tensile strength

D. More compressive strength and tensile strength
610. Dicor restoration is_______________?
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A. Castabel ceramic

B. None of the above

C. Heat pressed ceramics

D. Two coloured restorations

611. Which of the following statement is true regarding lathe cut low Copper silver alloy ?
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A. Requires least amount of mercury

B. Achieves high compressive strength at 1 hr.

C. Has tensile strength both at 15 minutes and 7 days is comparable to high copper, unicompositional alloys

D. Has lower cree value

612. Which cement is irritating to the pulp ?
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A. Zinc phosphate

B. Ethoxybenzoic acid

C. Carboxylate cement

D. Zinc oxide-eugenol cement

613. The setting of zinc phosphate may be retarded by ?
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A. Diluting the liquid with water

B. Decrease the addition of powder to liquid

C. Increase the addition of powder to liquid

D. Increased in the ratio of powder to liquid

614. PH of which cement remain below 7 even after 1 month after insertion into the cavity ?
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A. Zinc Phosphate

B. Silicate cement

C. Resin cement

D. Glass Ionomer Cement

615. Percentage of tin in low copper alloy is______________?
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A. 13-32%

B. 22-30%

C. 26-28%

D. 30-35%

616. Cavity varnishes have_____________?
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A. Excellent bonding to tooth

B. No bonding to tooth

C. Average bonding to tooth

D. Low bonding to tooth

617. About zinc oxide eugenol all are true except_______________?
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A. ZnO is converted to Zn(OH)2

B. Reaction is autocatalytic

C. Water is the byproduct of reaction

D. Dehydrated ZnO reacts with dehydrated eugenol
618. During amalgamation, trituration is done to_____________?
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A. Dissolve the alloy in mercury

B. Coat the alloy particle with mercury

C. Dissolve Hg in alloy

D. Remove excess mercury from the amalgam

619. Chemical method of strengthening porcelain involves_________________?
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A. Exchange of aluminium and sodium ions

B. Exchange of sodium and potassium ions

C. Exchange of aluminium and potassium ions

D. None of the above

620. Finishing and polishing of Amalgam make the restoration______________?
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A. Increased compressive strength

B. Decrease the tarnish and corrosion resistance

C. Increase the marginal strength

D. Increase in tarnish and corrosion resistance
621. In non zinc containing dental amalgam alloy the percentage of zinc present is______________?
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A. Less than 0.01%

B. None of the above

C. Less than 0.1%

D. Less than 0.02%

622. Amalgam achieves 70% of the strength by____________?
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A. 4 hours

B. 16 hours

C. hours

D. 8 hours
623. Co-efficient of Thermal exansion of amalgam is______________?
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A. 6.6 a (ppm k-1)

B. 11.4 a (ppm k-1)

C. 25.0 a (ppm k-1)

D. 14.0 a (ppm k-1)

624. For dental amalgam, the elastic modulus and tensile strength is______________?
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A. 350 Gpa and 10 120 Mpa

B. 40 Gpa and 60 100 Mpa

C. 21 Gpa and 27 55 Mpa

D. 360 Gpa and 125 130 Mpa

625. The cavity varnish applied reduces post operative sensitivity in amalgam restoration by____________?
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A. Decreasing conduction of heat to pulp

B. Minimize marginal leakage around restoration

C. By altering the chemical composition of restoration materials

D. By preventing penetration of corrosion products into the dentinal tubules

626. Which of the following is most important in strength ZOE_____________?
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A. Speed of mixing

B. Liquid powder ratio

C. Addition of few drops of water

D. Temperature of mixing stab

627. Which of the following cements have anti cariogenic properly________________?
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A. Calcium Hydroxide

B. Zinc silicophosphate

C. Zinc phosphate

D. ZOE