Question 1

What is the purpose of using dental cements as bases within a cavity preparation?

Accepted Answer

The reason for using cements as thermal insulating bases in deep cavity preparations is that although dentin is a poor thermal conductor, a thin layer of it does not provide enough thermal insulation for the pulp unless a cement base is used under the metal restoration.

Question 2

What is a material called if a liquid presents a contact angle of wettability greater than 90°?

Accepted Answer

A)   Viscous
B)   Thixotropic
C)   Hydrophilic
D)   Hydrophobic C

Question 3

What is the ratio of the force to the area called?

Accepted Answer

A)   Stress
B)   Strain
C)   Tensile strength
D)   Elastic modulus A

Question 4

Compare and contrast the terms absorption and adsorption.

Accepted Answer

The answer of Compare and contrast the terms absorption and...

Question 5

A new addition silicone impression material is tested for linear dimensional change upon setting. The result of -0.34% indicates that _______________ took place within 24 hours after setting.

Accepted Answer

A)   linear expansion
B)   linear shrinkage
C)   thermal expansion
D)   thermal shrinkage

Question 6

Because the thermal expansion of a restorative material usually does not match that of the tooth structure, a differential expansion or contraction occurs that may result in leakage of oral fluids between the restoration and tooth.

Accepted Answer

A)   Statement 1 is correct; statement 2 is correct.
B)   Statement 1 is correct; statement 2 is incorrect.
C)   Statement 1 is incorrect; statement 2 is correct.
D)   Statement 1 is incorrect; statement 2 is incorrect.

Question 7

Why are cavity varnishes and liners ineffective as thermal insulators?

Accepted Answer

A)   Used in thin layers
B)   High thermal conductivity
C)   Low coefficient of thermal expansion
D)   High coefficient of thermal expansion

Question 8

Which of the following materials has the highest rating related to thermal conductivity?

Accepted Answer

A)   Glass ionomer
B)   Gold alloy
C)   Enamel
D)   Dentin

Question 9

Explain the difference between ductility and malleability.

Accepted Answer

The answer of Explain the difference between ductility and malleability....

Question 10

"Measures the energy required to fracture a material" is the definition of which term?

Accepted Answer

A)   Ductility
B)   Resilience
C)   Toughness
D)   Malleability

Question 11

Which of the following restorative materials has a linear thermal coefficient of expansion that is lower than that of human teeth?

Accepted Answer

A)   Ceramics
B)   Composites
C)   Dental amalgam
D)   Unfilled acrylics and sealants

Question 12

The thermal coefficient of expansion _____ uniform throughout the entire temperature range and is usually _________ for liquids than solids.

Accepted Answer

A)   is; lower
B)   is; higher
C)   is not; lower
D)   is not; higher

Question 13

What occurs as the result of a discrepancy between the linear thermal coefficient of expansion between teeth and the restorative material if there is no bonding?

Accepted Answer

A)   Stress
B)   Strain
C)   Percolation
D)   Yield strength
E)   Elastic modulus

Question 14

What is the energy necessary to fracture called?

Accepted Answer

A)   Yield strength
B)   Toughness
C)   Stress
D)   Strain

Question 15

Detail the significance of thermal dimensional change.

Accepted Answer

The answer of Detail the significance of thermal dimensional change....

Question 16

With regard to wettability and water, what does a low contact angle indicate?

Accepted Answer

A)   The material is hydrophilic.
B)   The material is hydrophobic.
C)   The contact angle is greater than 90°.
D)   Both A and C are correct.
E)   Both B and C are correct.

Question 17

When a material reaches its ______________, deformation of a material becomes permanent.

Accepted Answer

A)   stress-strain curve
B)   ultimate strength
C)   elastic modulus
D)   yield strength

Question 18

What is the energy it takes to deform a material called?

Accepted Answer

A)   Relationship
B)   Resistance
C)   Resilience
D)   Rebound

Question 19

Which term refers to the cause of a metallic taste in the mouth?

Accepted Answer

A)   Corrosion
B)   Galvanism
C)   Percolation
D)   Contamination

Question 20

How is the percentage of dimensional change measured?

Accepted Answer

A)   An original length or volume
B)   The final length or volume
C)   The compressive strength
D)   The tensile strength
E)   The shear strength

Exam 2: Properties of Materials