Chapter 3 - Physical And Mechanical Properties Of Dental Materials

Front 1

What is abrasion resistance?

Back 1

The wear resistance of dental restorations of food and opposing teeth.

Front 2

Define bending.

Back 2

A combination of several types of stresses.

Front 3

What are biologic properties?

Back 3

The effects of the material on living tissue.

Front 4

What are chemical properties?

Back 4

They describe setting reactions and degradation of materials.

Front 5

What is the coefficient of thermal expansion?

Back 5

A measure of the change in volume or length in relation to the change in temperature.

Cool materials contract, heated materials expand.

Front 6

Define color.

Back 6

Hue - fundamental color: red, green, blue

Chroma - strength or saturation (pink vs red)

Value - light or darkness of a color (shades of gray)

Front 7

What is compression?

Back 7

A pushing or crushing stress (such as condensing amalgam).

Front 8

Define creep.

Back 8

A small change in shape when an object is under continuous compression

Front 9

What is density?

Back 9

The mass of a material in a given volume.

A common unit is gm/cm3

Front 10

What is elasticity?

Back 10

Stretching of atomic bonds

Front 11

What is elastic deformation?

Back 11

The initial change in length

Front 12

What is the elastic limit?

Back 12

the point at which permanent deformation begins (yield point)

Front 13

Define fatigue.

Back 13

Failure of a material after being stressed repetitively for a long time.

Front 14

What is force?

Back 14

a weight or load applied to an object

Front 15

What is fracture toughness?

Back 15

The measure of the energy required to fracture a material when a crack is present

Front 16

What is the Goldilocks principle?

Back 16

Not to hard, not to soft, just right.

Front 17

What is galvanic shock?

Back 17

Electricity flowing from the fork to the amalgam through the pulp.

Front 18

Define hardness.

Back 18

Indicates a material's ability to resist scratching and indentation.

Front 19

What is heat capacity?

Back 19

The measure of the amount of thermal energy that a material can hoard.

Front 20

What is heat of fusion?

Back 20

The amount of energy required to melt a material.

Front 21

Define heat of vaporization.

Back 21

The amount of energy required to boil a material

Front 22

Define load.

Back 22

It is the weight applied during force

Front 23

What are mechanical properties?

Back 23

They describe a materials ability to resist forces

Front 24

Define modulus of elasticity.

Back 24

The proportionality constant, or the slope of a graph of stress versus strain

Stress/strain

Front 25

What is percolation?

Back 25

The process of heating and cooling the accompanying opening and closing the gap

Front 26

Define permanent deformation

Back 26

the material does not return to its original length. The stress induced in the material is greater than the material's yield strength.

Front 27

What are physical properties?

Back 27

Based on the laws of physics. Describe mass, energy, force, light, and color.

Front 28

What is plastic deformation?

Back 28

the material does not return to its original length. The stress induced in the material is greater than the material's yield strength.

Front 29

What is Poisson's ratio?

Back 29

The ratio of the strain in the direction of the stress to the strain in a direction perpendicular to the stress.

Front 30

What is proportional limit?

Back 30

The point on the stress/strain plot at which the line starts to curve and plastic deformation begins.

Front 31

Define resilience.

Back 31

The ability to absorb energy and not be deformed

Front 32

Define shear.

Back 32

Parts of an object slide by one another.

Front 33

What is the shade guide?

Back 33

A set of color tabs or shades that are used for esthetic materials in dentistry.

Front 34

Define solubility.

Back 34

The ability of a material to dissolve in a liquid.

Front 35

What is specific heat capacity?

Back 35

The amount of energy needed to raise the temperature of one unit mass of that material by 1 degree C.

Front 36

Define strain.

Back 36

The change in length divided by the original length.

Front 37

Define stress.

Back 37

The force (load) divided by the cross sectional area of an object.

Stress = load/area

Front 38

What is stress concentration?

Back 38

Stress increases around defects (cracks, bubbles, scratches.)

Front 39

What is stress relaxation?

Back 39

A slow decrease in force over time.

Front 40

Define tension.

Back 40

A pulling stress

Front 41

What is thermal conductivity?

Back 41

The rate of heat flow through a material. (metal)

Front 42

What is torsion?

Back 42

A twisting force

Front 43

Define toughness.

Back 43

the energy absorbed up to the failure point on the stress/strain diagram

Front 44

What is the ultimate compressive strength?

Back 44

a compressive test

Front 45

What is ultimate strength?

Back 45

The point at which the material breaks

Front 46

What is ultimate tensile strength?

Back 46

a test of tensile strength

Front 47

What is vapor pressure?

Back 47

The measure of a liquid's tendency to become a gas (evaporate)

Front 48

Define viscosity.

Back 48

A material's ability to flow

Front 49

What is water sorption?

Back 49

The measure of a material's absorption of water

Front 50

Define wetting.

Back 50

measured by determining the contact angle of a liquid on a solid. A low contact angle indicates good wetting.

Front 51

What is the yield point?

Back 51

The point at which permanent deformation begins.

Front 52

What are the four properties of materials?

Back 52

Chemical

Physical

Mechanical

Biological

Front 53

Define interactions with x-rays concerning dental materials.

Back 53

Ceramics - radioluscent (grey)

Metals - radiopaque (white)

Front 54

Name and define four types of stress.

Back 54

Compression - a pushing or crushing stress

Tension - a pulling stress

Shear - sliding stress

Torsion - twisting force

Bending - combination of several types

Front 55

Name and define two time dependent properties.

Back 55

Creep - A small change in shape when an object is under continuous compression

Stress relaxation - A slow decrease in force over time.

Front 56

A drop of water on a popsicle is an example of:

Back 56

Good wetting (low contact angle)

Front 57

The tightening of a guitar string is an example of which type of stress?

Back 57

Tension

Front 58

The modulus of elasticity is an indication of what property of a material?

Back 58

Stiffness

Front 59

True or False

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.

Back 59

True

Front 60

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.

Back 60

No longer

Front 61

Which formula defines the modulus of elasticity?

Back 61

Stress/strain

Front 62

An example of a physical property is?

Back 62

Density

Front 63

A twisting force is termed?

Back 63

Torsion

Front 64

The ability of a material to dissolve liquid is termed?

Back 64

Solubility

Front 65

Elasticity is an example of which property?

Back 65

Mechanical

Front 66

The rate of heat flow through a material is referred to as?

Back 66

Thermal conductivity

Front 67

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 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?

Back 67

Coefficient of thermal expansion

Front 68

Fingernail polish remover has "solvent" properties, as it will remove the polish from our fingernails. Another property polish remover has it its tendency to evaporate. Fingernail polish remover can be said to have what type of pressure?

Back 68

A high vapor pressure

Front 69

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

Back 69

Compression

Front 70

A hardening cement having "low" _______________ can firmly hold a patient's gold crown in place for years in a wet environment.

Back 70

Solubility

Front 71

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

Back 71

Stress concentration.