Dental Materials Week 4 Ppt Review - Vocabulary

Front 1

List the 4 categories of Properties of Materials.

1. ___________________________
2. ___________________________
3. ___________________________
4. ___________________________

Back 1

1. Physical
2. Mechanical
3. Chemical
4. Biologic

Front 2

What are Physical Properties based on and what do they describe?

Back 2

● Based on the laws of physics
● Describe mass, energy, force, light, heat, electricity, and other properties

Front 3

What do Mechanical Properties describe and what do they dependent on?

Back 3

● Describe a material’s ability to resist forces
●Dependent on:
○Amount of the material
○Size of the object
○Shape of the object

Front 4

What do Chemical Properties describe?

Back 4

●Describe the:
○Setting reaction of materials
○Decay or degradation of materials

Front 5

What do Biologic Properties describe?

Back 5

● Describe the effects the material has on living tissue

Front 6

Physical Property - Density:
What is it? What does it depend on? Give an example.

Back 6

●Material mass per given volume
●Depends on:
○Type of atoms present
○Packing of the atoms
○Voids in the material
☆ Flatten a marshmallow—volume is decreased and density has increased ☆

Front 7

Physical Property - Boiling and melting points:
What are they?

Back 7

●Breaking of atomic bonds between atoms by thermal energy
☆ Temperature range vs. specific temperature ☆

Front 8

Physical Property - Vapor pressure
What is it? What is its relation to temperature?

Back 8

●Measure of a liquid’s tendency to evaporate and become a gas
●As temperature increases, vapor pressure increases

Front 9

Physical Property - Thermal conductivity

Back 9

●Rate of heat flow through a material
●Measured as heat flow over time
●Depends on:
○ Distance heat travels
○ Area in which heat travels
○Temperature difference between source and destination

Front 10

Ingestion of foods and beverages, even smoking, may alter wha? What does all forms of matter do they are heated and when cooled. What does this results in?

Back 10

● the temperature of the oral environment.
● expand; contract
● dimensional change.

Front 11

Acceptable materials used as restorations and replacements for tooth structure should have what characteristics?

Back 11

characteristics similar enough to those of the tooth.

Front 12

When given amalgam, gold, porcelain, and composite resin, which two materials are closest in expansion to enamel and dentin? Which two are closes in conductivity?

Back 12

|Structure | Expansion |Conductivity |
|Enamel | 11 | 2.0 |
|Dentin | 8 | 1.3 |
|Amalgam | 20-28 | 54 |
|Gold | 15 | 350 |
|Porcelain | 15 | 2.5 |
|Composite resin | 26-40 | 2.6 |

Front 13

Physical Property - Heat capacity and Specific heat capacity
What is heat capacity? What is spacific heat capacity?

Back 13

●Measure of the amount of thermal energy a material can hoard/hold/retain.
●Energy required to raise the temperature of one unit of mass of a material by 1°C.

Front 14

Physical Property - Heat of fusion and vaporization
What is heat of fusion? What is Heat of vaporization?

Back 14

●Amount of energy required to melt a material
●Amount of energy required to boil a material

Front 15

Physical Property - Coefficient of thermal expansion
What is Coefficient of thermal expansion? What does this mean in relation to larger and smaller objects of the same material?

Back 15

● Measure of the change in volume in relation to the change in temperature
● Larger objects of the same material expand more in quantity than smaller objects do, but larger objects expand by equal amounts in terms of percentage, a fractional change.

Front 16

Physical Property - Coefficient of thermal expansion
What is percolation? What does it result in?

Back 16

●Opening and closing of the gap between tooth structure and a restoration due to differences in coefficients of thermal expansion
●Results in:
○Microleakage
○Tooth sensitivity
○Recurrent decay

Front 17

Physical Property - Electrical conductivity
What materials are good electrical conductors? What materials are not poor electrical conductors?

Back 17

●Good electrical conductors
○Metals
●Poor electrical conductors (insulators)
○Polymers
○Ceramics

Front 18

Physical Property - Viscosity
What is viscosity? what is it dependent on? What is the difference between high viscosity and low viscosity?

Back 18

Ability of a material to flow
Temperature dependent
High viscosity = high contact angle = poor wetting = thick fluids
Low viscosity = low contact angle = good wetting = thin fluids

Front 19

Physical Property - Viscosity
What do thixotropic materials do? What are two examples?

Back 19

●Thixotropic materials flow more easily under mechanical forces.
●Examples:
○Catchup
○Toothpaste

Front 20

Physical Property - Retention
What is retention? How may it be secured?

Back 20

How the material will be retained within or on the tooth
May be secured by mechanical, chemical adhesion, or bonding between materials

Front 21

Physical Property - Retention
What is mechanical retention?

Back 21

● use of undercuts for the material to lock into place.

Front 22

Physical Property - Retention
What is chemical adhesion/bonding? What is this affected by?

Back 22

● use of materials that help to “glue” the dental material in place.
● Affected by wetting, viscosity, film thickness, and surface characteristics such as texture, cleanliness, moisture.

Front 23

Physical Property - Hardness
How is hardness measured? What is it?

Back 23

● Scientifically measured
● Ability of a material to resist forces of indentation

Front 24

Physical Property - Hardness
What are the Knoop harness numbers for:
Enamel, Dentin, Porcelain, and Acrylic denture teeth?

Back 24

● Enamel = 350
● Dentin = 70
● Porcelain = 400-500
● Acrylic denture teeth = 20

Front 25

Physical Properties - Hardness
What are Durometer measurements used for?

Back 25

● Used to determine hardness of:
○ Impression materials
○ Other elastic polymers

Front 26

Phisical Properties - Abrasion resistance
How does abrasion resistance relate to materials? What if the material is too hard? Too soft? What principle is this?

Back 26

● Harder materials are more resistant to abrasion
● Restorative material too hard—wears away opposing teeth
● Restorative material too soft—restoration wears away
● Goldilocks Principle—not too hard, not too soft, just right

Front 27

Physical Property - Solubility
What is solubility? What does excessive solubility in the mouth lead to?

Back 27

● Amount of material that dissolves in liquid
● Excessive solubility in the mouth leads to:
○ Loss of material
○ Recurrent decay

Front 28

Physical Properties - Soluble
What materials are very insoluble?
What materials are more soluble and tend to "wash out"?

Back 28

● Gold and porcelain are very insoluble.
● Materials for tooth colored restorations are more soluble and tent to “wash out”.

Front 29

Physical Properties - Whater sorption
What is water sorption? What is an example?

Back 29

● Material absorbs water
● Example: cookie dunked in milk

Front 30

Physical Properties - Color
What is Color? What does it vary by?
How is it standardized?

Back 30

● Psychological response to physical stimulus (light)
● Perception varies between individuals
● Standardization
○ by using shade
○ guides

Front 31

Esthetic:
What are the three components of color?

Back 31

●Hue- dominant color of the wavelength detected (yellow, brown, blue)
●Chroma- intensity or strength of the color; teeth are low intensity (think pink vs. red)
●Value- describes how light (white) or dark (black) the color is. Teeth have value ranges in the light scale.

Front 32

The color of teeth can also be determined by what?
What does transparent, opaque and translucency mean?

Back 32

●Color of teeth can also be determined by the way they reflect light
○Transparent– light passes directly through an object
○Opaque– light is completely absorbed by the object
○Translucency– the quality of partially transmitting and partially scattering light.

Front 33

Physical Properties - Interaction of materials with x-rays

Back 33

●Radiolucent
○Some ceramic materials
○Denture acrylic resin
●Radiopaque
○Metal restorations

Front 34

Mechanical Properties - Force
What is force?

Back 34

Weight or load applied to an object

Front 35

Mechanical Properties - Stress
What is stress?

Back 35

Force divided by the area in which it is applied

Front 36

Mechanical Properties - Elasticity
What is elasticity? What is something that has good elasticity?

Back 36

●Ability of a material to recover its shape completely after deformation from an applied force.
●Rubber bands have good elasticity.

Front 37

Mechanical Properties - Strain
What is strain? What is it measured as?

Back 37

●The change in length divided by the original length
●Measured as:
○Fraction
○Percentage

Front 38

Mechanical Properties - Stress
What is stress? What is it proportional and related to? What is it measured in?

Back 38

●Force that develops in a loaded object
●Proportional to load
●Related to size of the object
●Stress = load/area
●Measured in:
○Pounds per square inch (psi)
○Pascals (metric)

Front 39

What is the relationship of stress and strain?

Back 39

●Proportional
●Always occur together
●Modulus of elasticity
○Stress/strain
○Characteristic of a material and its atomic bonds
○High modulus of elasticity = stiff material

Front 40

What is the Stress-strain plot?
What is the elastic deformation?
What is plastic/permanent deformation?
What is elastic limit, proportional limit or yeild point?
What is ultimate strain?

Back 40

●Elastic deformation- object returns to its original shape after stress is removed
●Plastic/permanent deformation- stress to strain no longer proportional. Object will not return to its original shape
●Elastic limit, proportional limit, or yield point- maximum stress level at which complete recovery or strain occurs on release of the stress
●Ultimate strength- ultimate stress that can be withstood before breaking

Front 41

Mechanical Properties - Stress
What are the 5 types of stress?

Back 41

● Compression—pushing stress
● Tension—pulling stress
● Shear (slip)—sliding stress
● Torsion—twisting stress
● Bending—compression + tension stress

Front 42

Mechanical Properties - Force
What is force?

Back 42

●Force is a weight or a load that is applied to an object. Inside the object (the tooth), a stress develops to resist the applied force. The stress is equal to the force that is applied; they are in opposite directions. If the stress within the object cannot resist the force, distortion or deformation occurs and the object is strained.

Front 43

What is the relationship of force to stress? What is the relationship of force with strain?

Back 43

Stress is the amount of force exerted from within an object, strain is the amount of change that the force has produced

Front 44

Dimensional changes from stress
What is Ductility? What is malleability?

Back 44

●Ductility– the amount of dimensional change an object can withstand without breaking
●Malleability– the ability to be compressed and formed into a thin sheet without breaking

Front 45

When given amalgam, porcelain, composite resin, or acrylic, which two materials have the closest ultimate compressive strength to enamel and dintin? Which two have the closest ultimate tensile strength?

Back 45

|Structure |Ultimate compressive |Ultimate tensile
| | strength | strength
|Enamel | 56,000 | 1,500
|Dentin | 43,000 | 4,500
|Amalgam | 45,000-63,0000 | 7,000-9,000
|Porcelain | 43,000 | 5,400
|Composit | 30,000-60,000 | 6,000-9,000
|Acrylic | 11,000 | 9,000

Front 46

Mechanical Properties: Poisson Ratio
What is Poisson ratio? This means materials change shape how?

Back 46

●Ratio of strain in the direction of stress to the strain in the direction perpendicular to the stress
●Materials change shape in three dimensions

Front 47

Mechanical Materials - Resilience and Toughness
What is resilience? What is toughness?

Back 47

●Resilience - Material has the ability to absorb energy without becoming deformed
●Toughness - Energy absorbed up to the failure point on the stress-strain plot

Front 48

Mechanical Materials - Fracture Toughness
What is fracture toughness? Give two examples of materials with low-fracture toughness. Give an examples with high-fracture toughness.

Back 48

●Measure of the energy required to fracture a material when a crack is present
●Low-fracture toughness
○Glass
○Dental porcelain
●High-fracture toughness
○Metals

Front 49

Mechanical Materials - Fatigue
What is fatigue?

Back 49

Material/object failure due to being stressed repetitively for a long time

Front 50

Mechanical Properties - Time Dependent Properties
What is creep? What is stress relaxation?

Back 50

● Creep - Small change in shape when an object is under continuous compression
● Stress relaxation - Slow decrease in force over time

Front 51

Mechanical Properties - Stress Concentration
What is Stress Concentration? Give an example.

Back 51

● Stress increases around defects
● Increases likelihood of fracture
● Example: cutting glass

Front 52

Galvanism
What is galvanism?
What makes this current possible?
What may it result in?
What may patients commplain of?

Back 52

● Galvanism– transmission of electrical current between two dissimilar metals
● Environment containing moisture, acidity, and dissimilar metals makes the generation of an electrical current possible.
● Current may result in stimulation to the pulp called galvanic shock (think aluminum foil with braces). May feel a shock or complain of a metallic taste with introduction of dissimilar metal.