dental materials MCQs – Page 10

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

dental materials Mcqs
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

461. What is the working time of zinc polyacrylate cement ?
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A. 4 Minutes

B. 3 Minutes

C. 2 Minutes

D. 1 Minutes

462. In porcelain metal elements are embedded in the matrix of________________?
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A. Plastic

B. Resin matrix

C. Rubber matrix

D. Glass
463. Which of the following characterizes the silicate cement______________?
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A. Chemically attaches to the tooth structure

B. It produces thinnest film surface

C. It is pulpal irritant

D. It is highly cariogenic

464. Mercury intoxication in dental office mainly results from____________?
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A. Direct contact with the mercury

B. None of the above

C. Inhalation of mercury vapours

D. Ingestion of mercury

465. Age hardening is a process done at______________?
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A. Heating up to 200 450C for 15 30 min and quenching in water

B. Heating above 700C for 30 min and quenching in water

C. Heating at 700C for 1 hour and quenching in water

D. Heating at 700C for 10 15 min and quenching in water

466. Mercury rich condition in a slow setting amalgam alloy system in a resoration in______________?
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A. Merginal damage

B. All of the above

C. Accelerated corrosion

D. Fracture of the restoration

467. Which of the following are characteristic feature of high copper amalgam alloy ?
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A. Less marginal #

B. Low compressive strength

C. High creep

D. High marginal breakdown

468. What is the recommended for condensation of dental amalgam ?
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A. 25 lb

B. 3 pounds

C. 35 pounds

D. 15 lb

469. Increase in the residual mercury in silver amalgam filling can_____________?
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A. Tarnish and corrosion

B. Cause fracture of the filling

C. Increase the strength

D. Decrease condensation pressure

470. The chief advantage of zinc phosphate cement is its___________?
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A. Good compressive strength

B. Film thickness

C. Lack of irritation

D. Low solubility

471. Super abrasive is________________?
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A. Silicon arbide

B. Aluminum oxide

C. Sand

D. Diamond
472. The material used in its pure form in dentistry is______________?
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A. Gold

B. Silver

C. Amalgam

D. Composite

473. Pitting of direct filling old restoration usually results from_________________?
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A. Improper stepping of condenser point

B. Using contaminated gold foil

C. Poor finished preparation

D. Using small condenser point

474. Which one of the following dental cements does not contain water as part of the composition of the liquid component ?
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A. Zinc silicophosphate cement

B. Zinc oxide equgenol cement

C. Zinc polycarboxylate cement

D. Zinc Phosphate cement

475. The term trituration means____________?
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A. Lysing amalgam alloy

B. None of the above

C. Mixing of amalgam alloy and mercury

D. Removal of excess of mercury

476. The highest mercury concentration in amalgam filling is found_____________?
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A. None of the above

B. In the deepest part of the restoration

C. At the margin of the restoration

D. In the centre of the restoration

477. Condensation shrinkage of porcelain during firing depends on__________________?
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A. Rate of arriving at firing temperature

B. Uniformity of particle size

C. Type of investment used

D. Shape and size of particle
478. Advantage of zinc phosphate over GIC is______________?
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A. Tensile strength

B. High compressive strength

C. Diametral strength

D. High modulus of elasticity
479. Which one of the following dental cement accelerates the formation of reparative dentin ?
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A. Zinc oxide

B. Silica

C. Eugenol

D. Calcium Hydroxide
480. The largest component of amalgam alloy is_____________?
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A. Tin

B. Silver

C. Copper

D. Zinc

481. Which of the following bur is used in the preparation of cavity restored with porcelain fused to metal ?
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A. Diamond bur

B. Diamond but for porcelain and carbide bur for metal

C. Carbide bur

D. Stainless steel bur

482. Phenomenon in which porcelain appears different under varying light condition is______________?
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A. Opacification

B. Refractive optics

C. Translucency

D. Metamerism
483. The setting of zinc phosphate is accelerated by_____________?
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A. Adding a drop of oleic acid

B. Increasing mixing time

C. Adding a drop of water

D. Cooling the slab

484. Ceramics fired to metals are processed by_______________?
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A. Machining

B. Slip casting

C. Heat pressing

D. Sintering
485. Polycarboxylate cement is used for_____________?
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A. Leuting

B. Permanent restoration

C. Die material

D. Temporary restoration

486. In a high copper amalgam the phase, which is eliminated is_______________?
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A. Gamma 2

B. Gamma 1 and 2

C. Gamma 1

D. No phase is eliminated

487. High copper dental amalgams are superior to other amalgams because high copper dental amalgems______________?
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A. Are workable at lower Hg-alloy ratio

B. Have less marginal breakdown

C. Have less resistance to tarnish and corrosion

D. Have a higher ratio of tensile to compressive strength

488. Adequate mixing of mercury is indicated by_______________?
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A. Dry Mix

B. Shiny Mix

C. Short Mixing Time

D. None of the above

489. How soon after a moisture contamination does a zinc containing amalgam alloy start expanding________________?
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A. 24 hours

B. 7 days

C. 1-2 days

D. 3-5 days
490. The major component of zinc phosphate cement is_____________?
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A. Zinc

B. Phosphoric acid

C. Zinc oxide

D. None of the above

491. In method of firing: A shorter firing period at a higher temperature is considered better_______________?
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A. A large time period at a lower temperature is preferred

B. none of these

C. A short firing period at a very low temperature is preferred

D. A long firing period at a very high temperature is preferred
492. When selection the colour of cement to use for cementing a porcelain jacket crown, the powder being tested is best mixed with______________?
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A. Glycerin-water solution

B. Only water

C. Alcohol

D. Cement liquid

493. Why GIC is best restorative material in children_____________?
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A. Good marginal integrity

B. High strength

C. It has less occlusal wear

D. It can bond enamel & dentin
494. Which of the following constituents of amalgam alloy decreases expansion____________?
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A. Zinc

B. Tin

C. Copper

D. Silver

495. Moisture contamination of amalgam can lead to_____________?
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A. Delayed expansion

B. increased stresses

C. Shrinkage

D. Marginal breakdown

496. Dynamic creep is the______________?
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A. Continuing alloying between silver-tin alloy and mercury during the life of restoration

B. Deformation of set amalgam during function

C. Spread of amalgam during packing

D. Process whereby alloy is wetted by murcury

497. In type II gold alloys _______ Karat gold is used?
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A. 18 K

B. 22 K

C. 10 K

D. 24 K

498. Discolouration of silver alloy is due to_____________?
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A. Dry corrosion

B. Tarnish and corrosion

C. Wet corrosion

D. Tarnish

499. Outstanding clinical performance of dental amalgam restoration is related to its____________?
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A. Creep

B. Compressive strength

C. Corrosion

D. Tensile strength

500. Greening occuring when porcelains are fired on silver free alloys may be attributed to________________?
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A. Silver ionization by porcelains with high oxygen potential

B. Vaporization of silver from the walls of contaminated furnaces

C. Surface diffusion of silver from the marginal metal

D. More rapid silver diffusion in sodium containing glass