Dental Materials MCQS - Physical Properties

1. Stress is defined as:
A. An applied load or force
B. A deformation resulting from an applied load
C. An external force opposing an applied load
D. An internal force opposing an applied load

2. Strain is defined as :
A. An applied load or force
B. A deformation resulting from an applied load
C. An external force opposing an applied load
D. An internal force opposing an applied load

3. The proportional limit is defined as :
A. The maximum stress in a structure
B. The minimum force required to cause a structure to break
C. The maximum stress that can be induced without permanent deformation
D. The maximum elongation under tension that can be measured before failure

4. The modulus of elasticity is defined as:
A. The stress at the proportional limit
B. The strain at the proportional limit
C. The stress/strain ratio within proportional limit
D. None of the above

5. Compressive stress is computed by dividing the external force by the :
A. Area of the test specimen upon which the weight rests
B. Elasticity of the test specimen in strain
C. Length of the test specimen beneath the force
D. Strain of the test specimen per unit length

6. The greatest stress which can be produced in a material such that stress is directly proportional to strain is called :
A. The elastic limit
B. The proportional limit
C. The yield strength
D. Modulus of elasticity

7. The point at which stress of a material exhibits a specific limited deviation P is called :
A. Proportional limit
B. Tensile strength
C. Ultimate strength
D. Yield strength

8. Hardness number which does not depend upon the ductility of metal is :
A. Knoop Hardness Number (KHN)
B. Vicker's Hardness Number (VHN)
C. Rockwell Hardness Number (RHN)
D. Brinells Hardness Number (BHN)

9. Ability of an orthodontic wire to spring back to its original shape is evaluated by :
A. Brittleness
B. Resilience
C. Tensile strength
D. Toughness

10. Brinnel hardness number of a dental gold alloy is directly proportional to its :
A. Tensile strength
B. Elongation
C. Modulus of elasticity
D. Modulus of resilience

11. Ultimate tensile strength refers to :
A. Stress before rupture
B. Shear strain
C. Longitudinal compressive strength
D. Horizontal compressive strength

12. When solid gets wet completely, contact angle is :
A. 90 degrees
B. 0 degree
C. 0 - 90 degrees
D. Greater than 90 degrees

13. Property of the material which describes the resistance to abrasion is :
A. Hardness
B. Yield strength
C. Modulus of elasticity
D. None of the above

14. Modulus of elasticity means :
A. Rigidity or stiffness of the material
B. Ability to be stretched with permanent deformation
C. Ductility of a material
D. Malleability of a material

15. A material behaves in certain ways above and below the proportional limit on a stress strain curve. Which of the following is correct ?
A. Above the proportional limit, a material functions in a plastic manner ; whereas below the proportional limit, it behaves as an elastic
B. Above the proportional limit, a material functions in an elastic manner ; whereas below the proportional limit, it behaves as a plastic
C. Either A or B
D. Neither A nor B

16. Sublimation is the conversion of a :
A. Solid directly into gas
B. Gas to liquid and then to solid
C. Gas directly to liquid
D. Solid to liquid and then into gas

17. Which of the folllowing physical property can be used to estimate indirectly the proportional limit of gold alloys ?
A. Vickers hardness number
B. Knoop hardness number
C. Brinell hardness number
D. Rockwell hardness number

18. Ductility of a material is a measure of its :
A. Grain elongation
B. Annealing
C. Cold working
D. Work hardening

19. The ability of an alloy to withstand mechanical stresses without permanent deformation is reflected by its :
A. Resilience
B. Elastic limit / Elastic strain
C. Hardness
D. Fatigue resistance

20. The stiffness of a dental gold alloy is determined by its :
A. Proportional limit
B. Modulus of elasticity
C. Ultimate tensile strength
D. Flow

21. The ability of the base to resist occlusal forces and to support the restoration is affected by :
A. Compressive strength
B. Tensile strength
C. Young's modulus
D. Modulus of elasticity

22. Coefficient of thermal expansion of which of the following is most similar to that of the tooth ?
A. Gold inlay
B. Acrylic resin
C. Silicate cement
D. Gold foil

23. Flow of a material refers to :
A. Continued change of the material under a given load
B. The consistency of a material when mixing
C. The homogenecity of gypsum products
D. Dimensional change of the material during settings

24. The wetting of an adherent surface by an adhesive is related to :
A. Surface energy of the adherent
B. Surface texture of the adherent
C. Surface tension of the adherent
D. Nature of the adherent i.e. crystalline or amorphous

25. Which of the following properties of dental materials is time dependent ?
A. Ultimate strength
B. Resilience
C. Elastic limit
D. Creep

26. Which of the following has the highest modulus of elasticity ?
A. Dentin
B. Amalgam
C. Enamel
D. Composite resin

27. Which of the following hardness test is a micro hardness test :
A. Brinell
B. Knoop
C. Shore - A
D. Rockwell

28. A restorative material which has a high proportional limit, compared with one with a lower proportional limit would have :
A. Greater ductility
B. Greater toughness
C. A higher modulus of elasticity
D. More resistance to permanent deformation

29. A fluid having constant viscosity that does not depend upon the strain rate is said to be :
A. Viscoelastic
B. Pseudoplastic
C. Plastic
D. Newtonian

30. Liquids which become more rigid as the rate of deformation increases is termed as :
A. Thixotropic
B. Pseudoplastic
C. Dilatant
D. Newtonian

31. Which one of the following is the result of applying a load to a wire below its modulus of elasticity on a load deflection diagram ?
A. Fracture of the wire
B. Permanent deformation
C. Spring back
D. Increase in stiffness

32. The strain that occurs when a material is stressed to its proportional limit is :
A. Resilience
B. Maximum flexibility
C. Toughness
D. Elastic limit

33. KHN of enamel is close to :
A. Pure gold
B. Amalgam
C. Porcelain
D. Composite

34. Space lattice refers to :
A. Inter atomic movement
B. Inter atomic imbalance
C. Arrangement of molecules
D. Arrangement of atoms

35. The elastic or plastic deformation to fracture a material is its :
A. Toughness
B. Brittleness
C. Young's modulus
D. Proportional limit

36. Munsell system is used to :
A. Define and measure color qualitatively
B. Define and measure physical properties of gold alloys
C. Evaluate brittleness of different alloys
D. Measure different colors quantitatively

37. The knoop hardness number of microfilled composite restorative material ranges from :
A. 50-60 KHN
B. 25-35 KHN
C. 15-20 KHN
D. 40-48 KHN

38. A crystal in metal substructure is :
A. Grain
B. Nucleus
C. Stroma
D. None

39. Etching of dentin does not include :
A. Removal of smear layer
B. Exposure of collagen fibres
C. Opening of dentinal tubules
D. Increases surface energy
40. When two metals are completely miscible in liquid state and they remain completely mixed on solidification, the alloy formed is called :
A. Solid solution
B. Eutectic mixture
C. Peritectic mixture
D. Inter metallic compounds

41. Which of the following non metal conducts electricity ?
A. Carbon
B. Acrylic
C. Porcelain
D. Graphite

42. For adhesion to be present between solid and liquid, which of the following must be true ?
A. Liquid should wet solid surface
B. Mechanical interlocking should be present
C. Should have high contact angle
D. All of the above

43. The melting point of silver is :
A. 1063 degree centigrades
B. 960 degree centigrades
C. 850 degree centigrades
D. 1123 degree centigrades

44. Brazillian test is used to determine the ultimate tensile strength of :
A. Ductile materials
B. Flexible materials
C. Brittle materials
D. Malleable materials

45. Angle between adhesive and adherent is zero degree. It indicates :
A. Complete wetting of surfaces
B. Rough surfaces between adhesive and adherent
C. Adherent and adhesive molecules are tangent to each other
D. Irregularities present on adherent surface

46. KHN value of enamel is :
A. 450
B. 343
C. 68
D. 40

47. Maxwell - Voigt model is to determine :
A. Elastic behaviour
B. Plastic behaviour
C. Viscoelastic behaviour
D. All of the above

48. A material which partially transmits light and partially scatters it is called :
A. Reflector
B. Translucent
C. Transparent
D. Opaque

49. Material which has high compressive strength and low tensile strength is classified with the property of :
A. Ductility
B. Malleability
C. Resilience
D. Brittleness

50. The forces that hold atoms together are called :
A. Primary forces
B. Secondary forces
C. Cohesive forces
D. Ionic forces

51. The simplest alloy is a :
A. Solid solution
B. Eutectic alloy
C. Peritectic alloy
D. Ternary alloy

52. Coefficient of thermal expansion of tooth enamel is closest to :
A. Silicate cement
B. Composite
D. Polycarboxylate

53. In measuring Vicker's hardness number, which of the following is used ?
A. Spherical indentor
B. Steel ball indentation
C. Rhomboid shaped indenter
D. 136 degree diamond pyramid

54. Deformation that is recovered upon removal of an externally applied force or pressure is known as :
A. Young's modulus
B. Plastic strain
C. Elastic strain
D. Flexural strain

55. A good adhesive should possess all of the following EXCEPT :
A. High adherend wetting
B. High contact angle
C. Low contact angle
D. High flow

56. Molecule with permanent dipole is :
A. Oxygen
B. Helium
C. Liquid nitrogen
D. Water

57. Time dependent deformation produced in a completely set solid subjected to a constant stress is termed as :
A. Static creep
B. Elongation
C. Dynamic creep
D. Flexibility