Intro to Biomaterials

Question 1

What are the three main classes of materials?

Answer 1

1. Polymers
2. Ceramics
3. Metals

Question 2

_________ have the properties of being strong, ductile, and hard.

Answer 2

Metals

Question 3

_________ have the properties of being hard, brittle, and strong.

Answer 3

Ceramics

Question 4

________ have the properties of being soft, ductile, and weak.

Answer 4

Polymers

Question 5

Which material has the lowest processing temperature?

Answer 5

Polymers

Question 6

Which material is used as a direct processing material?

Answer 6

Polymers

Question 7

What are metal alloys and what properties are associated with them.

Answer 7

Mixture of two or more metals.

Stronger and less ductile

Question 8

How are metals bonded?

Answer 8

Metallic bonds

Question 9

Describe the process as metal goes from molten to cool.

Answer 9

Single atoms -> crystal growth -> formation of grains (polycrystalline structures)

Question 10

What type of bonds are associated with ceramics?

Answer 10

Ionic and covalent bonds

Question 11

T/F: Metallic bonds are stronger than both ionic and covalent bonds.

Answer 11

FALSE.

Both ionic and covalent are stronger than metallic bonds

Question 12

Which is a stronger bond, covalent or ionic?

Answer 12

Covalent

Question 13

T/F: Ceramics involve only non-metallic elements.

Answer 13

FALSE.

Both metallic and non-metallic

Question 14

What is the building block of most ceramics?

Answer 14

SiO4

Question 15

T/F: Crystalline microstructure of ceramics is involved with long range order.

Answer 15

TRUE

Question 16

T/F: Noncrystalline ceramic microstructure is involved with long range order.

Answer 16

FALSE

Short range order

Question 17

What type of microstructure do most dental ceramics have?

Answer 17

Semicrystalline or polycrystalline

Question 18

How is porcelain processed?

Answer 18

Sintering or melting at high temperatures

Question 19

T/F: Polymers form ionic bonds.

Answer 19

FALSE

Covalent bonds!

Question 20

Do polymers have a low or high molecular weight?

Answer 20

HIGH

Question 21

T/F: Polymers contain mostly nonmetallic elements.

Answer 21

TRUE

Question 22

How do polymers get their strength and properties?

Answer 22

The entanglement of a long chain of covalent bonds.

Question 23

What are the steps in the polymerization process?

Answer 23

1. Activation: free radical initiation
2. Initiation: free radical combines with monomer opening
3. Propagation: chain growth, volume decrease, shrinkage
4. Termination

Question 24

What are the three ways polymerization can be initiated?

Answer 24

1. Light
2. Heat
3. Chemical mixing

Question 25

T/F: Polymerization reactions are fast and may generate a lot of heat.

Answer 25

TRUE

Question 26

What is the importance of polymerization in dentistry?

Answer 26

Allows for direct placement of a flowable material, followed by rapid processing into a stable material

Question 27

What is the major metal that allows for direct processing?

Answer 27

Amalgam

Question 28

What ceramic allows for direct processing?

Answer 28

Cements

Question 29

T/F: Temporary crowns are made from cross linked polymers.

Answer 29

FALSE. Linear

Question 30

T/F: Adhesives and restoratives are made from crosslinked polymers.

Answer 30

TRUE

Question 31

What is a composite?

Answer 31

Physical mixture of metals, ceramics, and polymers.

Question 32

What is the rule of mixtures?

Answer 32

By understanding the phases present in the structure of a material and its interactions, properties can be predicted

Question 33

How much filler is typically found in a composite and what are common filler types?

Answer 33

75-80 wt% ``` Silicate glass (1-100 um) Colloidal silica (.05 um) ```

Question 34

If I wanted a composite with a very fine surface would I want one with silicate glass or colloidal silica?

Answer 34

Colloidal silica because it is smaller

Question 35

What happens as a composite has an increased filler volume.

Answer 35

Strength, modulus, and viscosity all INCREASE Shrinkage DECREASES

Question 36

What is the specific gravity of a material?

Answer 36

Density of the material/density of water

Question 37

T/F: Most things expand when heated, and contract when cooled.

Answer 37

TRUE

Question 38

List the three major dental materials in order from least to greatest potential for thermal expansion.

Answer 38

Ceramics (1-15) Metals (10-30) Polymers (30-600)

Question 39

What is the coefficient of thermal expansion for teeth? Amalgam? Composite?

Answer 39

``` Tooth = 9-11 Amalgam = 25 Composite = 28-35 ```

Question 40

Why do metals need an insulator such as base?

Answer 40

They have a high thermal conductivity and the pulp cannot withstand large temperature changes for long periods of time.

Question 41

T/F: Composites have low thermal conductivity so they do not need base.

Answer 41

TRUE

Question 42

Color is defined in a _______ _________ coordinate system.

Answer 42

Three dimensional

Question 43

What are the three dimensions of color?

Answer 43

Hue: wavelength, color Value: intensity, brightness Chroma: purity, concentration

Question 44

What is metamerism?

Answer 44

When two objects appear the same color under one light source and different under another light source