medical MCQs – Page 134

Practise multiple-choice questions from medical for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

2661. Inelastic impression material is_____________?
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A. Impression compound

B. Alginate

C. Polyether

D. Agar-agar

2662. Flux is used during casting to________________?
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A. Speed the burnout process

B. Replace casting wax

C. Remove the oxides formed on the gold alloy

D. Lower the melting point

2663. Gap between true end of casting ring and wax pattern should be______________?
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A. inch

B. inch

C. 3/8 inch

D. one inch

2664. Which of the following is not affected by saliva ?
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A. None of the above

B. Impression plaster

C. Impression paste

D. Silicon impression material

2665. In a metal ceramic crown for a FPD the function of tin, indium which are readily oxidized minor constituents is to________________?
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A. Decrease porosity

B. They react with the porcelain opaque layer, which masks the metal

C. Improve bonding

D. Improves the thermal expansion between the metal and porcelain

2666. Minimum flow of Type-I impression compound at mouth temperature is___________________?
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A. 8%

B. 4%

C. 6%

D. 10%

2667. Plaster mix____________?
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A. 2% potassium sulphate is accelerator

B. All of the above

C. Citrates are retarders

D. Rapid spatulation results in decreased setting time

2668. Casting shrinkage is compensated by_______________?
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A. Wax expansion

B. All of the above

C. Thermal expansion

D. Hygroscopic expansion

2669. The product, which is obtained by calcining gypsum under steam pressure at 120-130C or by dehydrating gypsum in the presence of sodium succinate is_______________?
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A. Orthorhombic anhydrate

B. Calcium sulphate dihydrate

C. Beta hemihydrates

D. Alpha hemihydrates
2670. The yield strength of AUstenite (NiTi alloy) is______________?
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A. 700 Mpa

B. 240 Mpa

C. 560 Mpa

D. 100 Mpa

2671. Which is best material for RPD impression_______________?
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A. None of the above

B. Impression plaster

C. Reversible hydroollioid

D. Irreversible hydrocolloid
2672. The base constituents of dental waxes come from three main sources except______________?
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A. Animal

B. Vegetable

C. Insect

D. Mineral

2673. Quartz in investment material is added for_______________?
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A. Expansion components for casting shrinkage

B. Contraction

C. Strength

D. Decrease strength

2674. Function of wetting agents used in casting procedure is_________________?
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A. To felicitate wetting of ring liner

B. To felicitate mixing investment

C. To reduce contact angle of liquid with max surface

D. For better wax elimination

2675. Elastomers except: Polyether are_______________?
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A. Potassium alginates

B. Hydrophobic

C. Water loving impression materials

D. Hydrophilic

2676. Who was the first person to introduce cast inlay restoration into dentistry ?
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A. G.V. Black

B. William H Taggart

C. Bowen

D. Buonocore

2677. All of the following statements about an alginate impression are EXCEPT________________?
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A. It may exhibit fluid exudates on the surface as a result of imbibition of water

B. It will take up water and expand if kept wet

C. It should be rapidly displaced from the mouth

D. It will shrink as a result of syneresis

2678. Which of the following decrease with strain hardening______________?
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A. Surface hardness

B. Proportion limit

C. Strength

D. Corrosion resistance
2679. The best way to remove a hydrocolloid impression from the patients mouth is____________?
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A. Sudden jerking of the impression to prevent tearing

B. Slight rocking of the impression to disengage it from the undercut

C. Supporting the impression along with the tray to prevent disengaging of the tray alone

D. Wetting the periphery of the impression with moist cotton to break the peripheral seal

2680. Disadvantage of having a short sprue is________________?
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A. Rapid solidification of metal

B. Incomplete evacuation of gases

C. Difficulty in removing casting from investment

D. No place for reservoirs