Dental Materials Ch. 3

Question 1

a drop of water on a popsicle is an example of

(a) Poor wetting (low contact angle)
(b) Good wetting (high contact angle)
(c) Good wetting (low contact angle)
(d) Poor wetting (high contact angle)

Answer 1

(c) Good wetting (low contact angle)

Question 2

the tightening of a guitar string is an example of which of the following stresses

(a) Compression
(b) Torsion
(c) Shear
(d) Tension

Answer 2

(d) Tension

Question 3

the modulus of elasticity is an indication of what property of a material

(a) Resilience
(b) Strength
(c) Stiffness
(d) Tension

Answer 3

(c) Stiffness

Question 4

cooled materials will contract, and heated materials will expand. a measurement of this change in volume in relation to change in temperature is called the coefficient of thermal expansion

(a) The first statement is true; the second statement is false.
(b) The first statement is false; the second statement is true.
(c) Both statements are true.
(d) Both statements are false.

Answer 4

(c) Both statements are true.

Question 5

when a stress is induced in a material that is greater than the material’s yield strength, the stress is ______ proportional to the strain, and the material does not return to its original shape

(a) Always
(b) No longer
(c) Equally
(d) None of the above

Answer 5

(b) No longer

Question 6

which formula defines the modulus of elasticity

(a) stress/strain
(b) stress2/strain
(c) strain/stress
(d) 2 × stress/strain

Answer 6

(a) stress/strain

Question 7

an example of a physical property is

(a) Density
(b) Strength
(c) Stiffness
(d) Setting reaction

Answer 7

(a) Density

Question 8

a twisting force is termed

(a) Compression
(b) Shear
(c) Tension
(d) Torsion
(e) Bending

Answer 8

(d) Torsion

Question 9

the ability of a material to dissolve in liquid is termed

(a) Viscosity
(b) Water sorption
(c) Solubility
(d) Wetting

Answer 9

(c) Solubility

Question 10

elasticity is an example of which of the following properties

(a) Physical
(b) Mechanical
(c) Chemical
(d) Biologic

Answer 10

(b) Mechanical

Question 11

the rate of heat flow through a material is referred to as

(a) Heat of fusion
(b) Coefficient of thermal expansion
(c) Heat capacity
(d) Thermal conductivity

Answer 11

(d) Thermal conductivity

Question 12

Jennifer is a practicing dental hygienist who goes to a nearby restaurant each day for lunch. she often orders a cola with ice and a bowl of homemade soup. as she eats and drinks her composite restorations (tooth colored) and tooth structure are expanding and contracting at different rates. this change in volume or length of these materials due to the hot food and cold drink is referred to as

(a) Heat of fusion
(b) Coefficient of thermal expansion
(c) Heat capacity
(d) Thermal conductivity

Answer 12

(b) Coefficient of thermal expansion

Question 13

fingernail polish remover has solvent properties as it will remove the polish from our fingernails. another property polish remover has is its tendency to evaporate. fingernail polish remover can be said to have

(a) A high vapor pressure
(b) A low vapor pressure
(c) No vapor pressure
(d) An intermittent vapor pressure

Answer 13

(a) A high vapor pressure

Question 14

_______ is the force used to condense an amalgam in a
preparation.

(a) Solubility
(b) Compression
(c) Stress concentration
(d) Viscosity

Answer 14

(b) Compression

Question 15

A hardened cement having “low” ______________ can firmly hold a patient’s gold crown in place for years in a wet envi-
ronment.

(a) Solubility
(b) Compression
(c) Stress concentration
(d) Viscosity

Answer 15

(a) Solubility

Question 16

________ is the term given to the increase of stress around defects within an object.

(a) Solubility
(b) Compression
(c) Stress concentration
(d) Viscosity

Answer 16

(c) Stress concentration