biomaterials

Question 1

3 main classes of materials

Answer 1

1. metals
2. ceramic
3. polymers

Question 2

mechanical properties of metals

Answer 2

1. hard
2. ductile-tough
3. strong

Question 3

mechanical properties of ceramic

Answer 3

1. hard
2. brittle
3. strong

Question 4

mechanical properties of polymers

Answer 4

1. soft
2. ductile-tough
3. weak

Question 5

which have high processing temperatures

Answer 5

metals and ceramics

Question 6

which tend to be used as direct processing materials

Answer 6

polymers

Question 7

which tend to have low processing temperatures

Answer 7

polymers

Question 8

metal bonding characteristics

Answer 8

1,2,3 electrons in their outer shell
electrons are key
electrons are loosely bonded to nucleus
electrons have free mobility 
thermal and electrical conductivity 
ductility- bend without breaking

Question 9

metal alloys

Answer 9

mixture of two or more metals
cast metal for crowns
amalgams

Question 10

solid solution alloy is more what compared to pure metal

Answer 10

stronger, less ductile

Question 11

microstructure of metals

Answer 11

polycrystalline grain structure

Question 12

ceramic bonding characteristics

Answer 12

ionic and covalent bonds
both are stronger than metallic bonds
covalent > ionic
ionic bonds- electron acceptor/donor
covalent bonds- equally share electrons

Question 13

microstructure of ceramics (3 most common metallic oxides) (building block)

Answer 13

mixture of metallic and non-metallic elements
1. SiO2
2. Al2O3
3. K20
SiO4 tetrahedron

Question 14

crystalline structures of ceramics

Answer 14

long range order

crystalline silicate-quartz or crystobilate

Question 15

noncrystalline structures of ceramics

Answer 15

short range order no long range or amorphous silicate-glass

Question 16

most dental ceramics are ____ or _____

Answer 16

simicrystalline or polycrystalline

Question 17

building block of dental porcelain

Answer 17

SiO4 tetrahedron- primarily a glass with some crystalline residuals

Question 18

polymer bonding characteristics

Answer 18

covalent bonds
high molecular weight
long molecules composed of mainly nonmetallic elements
are entangled long chains
“cooked spaghetti”- entanglement gives strength

Question 19

polymer formation

Answer 19

liquid (monomers)- solid (polymers) Polymerazation

Question 20

resin matrix of polymerization

Answer 20

monomers

iniator

Question 21

polymerization step 1

Answer 21

Activation- free radical initiation

Question 22

polymerization step 2

Answer 22

initiation- free radical combination with monomer unit, double bond opening

Question 23

polymerization step 3

Answer 23

propagation- chain growth, volume decreases, shrinkage

Question 24

polymerization step 4

Answer 24

termination

Question 25

monomer functional groups

Answer 25

linear chain | crosslinked (branched)

Question 26

linear chains

Answer 26

monomethacrylates

Question 27

crosslinked chains

Answer 27

dimethacrylates

Question 28

polymerization initiated by what 3 things

Answer 28

light heat chemical mixing

Question 29

why is polymerization important

Answer 29

``` direct placement flowable material trigger for setting repaid setting room temp setting run ```

Question 30

direct placement vs indirect placement

Answer 30

direct- one visit, less preparation, don't last as long | indirect- multiple visit, last very long, expense

Question 31

which are indirect placement

Answer 31

metals and ceramics (exceptions metals- amalgam, ceramics- cements

Question 32

which is direct placement

Answer 32

polymers

Question 33

use of polymers in dentistry

Answer 33

provisionals- temp crowns (linear) adhesives- crosslinked registered materials- impression materials

Question 34

composites

Answer 34

physical mixture of metals, ceramics, polymers | want to get some intermediate of all the properties

Question 35

composite rule of mixture

Answer 35

By knowing the phases present in the structure of any material and interfacial interactions, it is possible to predict the overall properties fairly well

Question 36

composite dispersed phase

Answer 36

glass fillers

Question 37

composite matrix phase

Answer 37

monomer resin

Question 38

fillers

Answer 38

are chemically bonded to resin phase to improve properties (silane coupling agents)

Question 39

2 types of fillers

Answer 39

silicate glass | colloidal silica

Question 40

how do fillers affect properties

Answer 40

increase strength, modulus, viscosity and decreases shrinkage

Question 41

increasing filler size increases ______

Answer 41

surface roughness

Question 42

most dense to least dense materials

Answer 42

metallic, ceramic, polymer

Question 43

density =

Answer 43

weight/unit volume

Question 44

thermal expansion

Answer 44

most things expand when they heat up and contract when cooled.

Question 45

thermal expansion coefficient

Answer 45

The degree of expansion divided by the change in temperature

Question 46

heat flow

Answer 46

thermal conductivity. teeth are insulators due to high mineral content

Question 47

thermal conductivity

Answer 47

rate of heat conduction

Question 48

metals have _____ heat conductivity so they need what

Answer 48

high, need thermal insulator like base

Question 49

composites have ______ heat conductivity and do not need a what

Answer 49

low, base

Question 50

how is color defined?

Answer 50

3D coordinate system

Question 51

what are the 3 dimensions

Answer 51

Hue value chroma

Question 52

what is hue

Answer 52

wavelength | color

Question 53

what is value

Answer 53

intensity | brightness

Question 54

what is chroma

Answer 54

purity | density or concentration

Question 55

what is metamerism

Answer 55

when two objects appear the same color under one light source but different color under another light source

Question 56

mercury to alloy ratio

Answer 56

.5 depends on commercial product, modern products 42-45% Hg by weight

Question 57

factors for setting process

Answer 57

composition, size and shape of alloy particles

Question 58

two types of alloy particle shape

Answer 58

spherical | lathe-cut particles

Question 59

which particle resist forces of condensation more

Answer 59

lathe-cut particles- wetted with higher mercury:allow ratio

Question 60

how many sizes are typically observed in spherical particles

Answer 60

3

Question 61

how many particles are observed in lathe-cut particles

Answer 61

wide range usually, intentionally done by manufacturer for optimum condensation

Question 62

what are bricks

Answer 62

alloy particles in set material

Question 63

when is Hg found?

Answer 63

reaction phase, no free mercury after setting reaction.

Question 64

what is n'

Answer 64

Cu6Sn5 product of set reaction.

Question 65

advantages of dental amalgam

Answer 65

inexpensive easily prepared direct restorative material margin sealing capability.

Question 66

disadvantages of dental amalgam

Answer 66

poor esthetics compared to resin composites weakening of tooth from removal of tooth structure recurrent caries brittle nature of material wastewater pollution with Hg sensitivity of properties to manipulation

Question 67

general setting reaction for amalgam is...

Answer 67

alloy + Hg ---> dental amalgam

Question 68

majoy elements in alloy are

Answer 68

silver, tin, 2-30% copper and 0-1% zinc

Question 69

which should be selected more high or low copper

Answer 69

high copper- greater clinical longevity of restoration s and much lower creep values