dental materials Mcqs
2. Which of the following will produce the most rigid restoration for framework of same dimension ?
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A. Partial denture casting gold in hardened condition

B. Wrought alloy

C. Cobalt-chrome alloys

D. Palladium alloys

4. Which of the following procedure is indicated to produce cross-linking in the polymerization of linear chains of acrylic_______________?
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A. Addition of grain refining agents

B. Increasing the amount of heat required for linear polymerization

C. Incorporation of terminating agents

D. Addition of difunctional monomers
5. The elastic of plastic deformation to fracture a material is its_______________?
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A. Youngs modulus

B. Proportional limit

C. Brittleness

D. Toughness
6. Acid-etching is done for_______________?
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A. 60 seconds

B. 90 seconds

C. 120 seconds

D. 30 seconds
8. Radio opacity to composite resins is rendered by_______________?
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A. Barium glass and strontium glasses

B. Silica glass

C. Organic matrix

D. Fluoride particles

11. NiTi alloy have_______________?
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A. Shape memory

B. Hyper rigidity

C. Corrosion resistance

D. Weldable properties

12. Etching of dentin does not include_____________?
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A. Exposure of collagen fibers

B. Increases surface energy

C. Opening of dentinal tubules

D. Removal of smear layer

13. Acrylic resins are used for______________?
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A. Denture base

B. All of the above

C. Anterior restorations

D. Temporary bridges

14. Co-efficient of thermal expansion is highest for_____________?
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A. Gold alloy

B. Acrylic resin

C. Silicate cement

D. Amalgam

16. Space lattice refers to_______________?
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A. Arrangement of atoms

B. Inter atomic movement

C. Arrangement of molecules

D. Inter atomic imbalance

17. A crystal in metal substructure is_______________?
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A. None of the above

B. Stroma

C. Grain

D. Nucleus

18. Denture acrylics contain cross-linking agents mainly to improve their_____________?
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A. Surface hardness

B. Craze resistance

C. Tissue compability

D. Internal color

19. Ductility of a material is a measure of its_______________?
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A. Anealing

B. Cold working

C. Work hardening

D. Grain elongation
21. Porosity present in a acrylic denture is usually the result of______________?
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A. Insufficient acrylic resin monomer

B. Lack of sufficient pressure applied to flask

C. A prolonged curing cycle

D. Prolonged bench cooling after curing

22. Marginal leakage related to temperature change occurs to the greatest extent with_______________?
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A. Composite resin

B. Direct filling gold

C. Amalgam alloy

D. Unfilled resin
23. Property of the material, which describes the resistance to abrasion, is_________________?
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A. Modulus of elasticity

B. None of the above

C. Yield strength

D. Hardness
24. Etchant preferred in gel from than in liquid form________________?
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A. Helps in visualization while placement

B. Enhance and concentrate the action of acid

C. Better control over placement

D. None of the above

25. To cure a heat cure resin, a proper heating cycle is necessary_____________?
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A. To prevent volume expansion

B. To prevent warpage

C. To prevent the porosity

D. All of the above

27. The melting point of silver is_____________?
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A. 1123 Centrigrade

B. 1063 centigrade

C. 850 Centrigrade

D. 960 Centigrade
28. Insufficient closure of the flasks during packing of denture base resin can result in_____________?
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A. Poor colour stability

B. Decrease in vertical dimension

C. Increase in vertical dimension

D. Less polymerization shrinkage

29. Sublimation is the conversion of a___________________?
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A. Gas directly to liquid

B. Solid to liquid and then to gas

C. Gas to liquid and then to soild

D. Solid directly to gas
30. Inadequate pressure application during flasking_______________?
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A. Increases vertical dimension

B. Causes poor quality of colour

C. Causes fracture of denture

D. Causes teeth to be shrunken in investment

31. Polymerisation of heat-cured methyl methacrylate is initiated by______________?
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A. Hydroquinone

B. Methyl ether

C. Benzoyl peroxide free radical

D. Tertiary amine

32. Tempering of steel cause________________?
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A. Increases hardness

B. decreases its toughness

C. Increase ductility

D. Increases its toughness

33. When restoring a tooth with resin material, acid etching can do all of the following except______________?
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A. Condition the tooth surface for better wetting

B. Increase the surface area

C. Permit chemical bonding between resin and enamel

D. Create surface irregularities in enamel for better mechanical retention of resin

34. Bonding of composite resins to tooth structure is by________________?
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A. Ionic bond

B. Mechanical

C. Vanderval forces

D. Covalent bond

35. Subsurface porosity is due to_____________?
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A. Thermal changes

B. Packing past the dough stage

C. Thickness of the resin

D. Lack of temperature

36. Modulus of elasticity means_______________?
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A. Ductility of a material

B. Rigidity or stiffness of the material

C. Malleability of the metal

D. Ability to be stretched with permanent deformation

37. Dentin bonding agents usually contain_____________?
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A. Only Hydrophilic component

B. Hydrophobic and hydrophilic component

C. Lyophillic and lyophobic component

D. Only Hydrophobic component

38. Inorganic phase of the composites aid in_______________?
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A. Increasing the mechanical strength

B. All of the above

C. Reducing the polymerization shrinkage

D. Decreasing the coefficient of thermal expansion

39. All of the following statements about the differences between self-polymerizing acrylic resins and heat-cured resins are true EXCEPT______________?
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A. The former have a lower molecular weight

B. The former have higher residual monomer content

C. The former have greater transverse strength

D. The former are more porous

40. The point at which a stress of a material exhibits a specific limited deviation P is called_______________?
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A. Ultimate strength

B. Yield strength

C. Tensile strength

D. Proportional limit

41. Which of the following physical property can be used to estimate indirectly the proportional limit of gold alloys ?
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A. Rockwell hardness number

B. Brinell hardness number

C. Knoop hardness number

D. Vickerss hardness number

42. The wetting of an adherent surface by an adhesive is related to________________?
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A. Surface energy of the adherent

B. Surface texture of the adherent

C. Nature of the adherent that is crystalline or amorphous

D. Surface tension of the adherent

43. Stainless steel orthodontic wire can be hardened by________________?
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A. Age hardening

B. Work hardening

C. Tempering

D. Precipitation hardening

44. The strength of a gypsum investment is dependent on_______________?
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A. Copper

B. Carbon content

C. Silica content

D. Gypsum
45. A thinner mix of a gypsum bonded investment will_______________?
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A. Produce a smoother casting

B. Increase thermal expansion

C. Decrease setting expansion

D. Increase setting expansion

46. 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. Improve bonding

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

C. Improves the thermal expansion between the metal and porcelain

D. Decrease porosity

47. In measuring Vickers hardness no. Which of the following is used________________?
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A. Steel ball indentation

B. Rhomboid shaped indenter

C. Spherical indenter

D. 136-degree diamond pyramid
49. Which of the following is an example of a composite material ?
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A. Wax

B. A filled resin

C. Gold alloy

D. Colloidal silica