Biomaterials Test 1

Front 1

what are the 4 types of materials?

Back 1

metals
ceramics
polymers
composites

Front 2

what type of material is opaque, heavy, dense, ductile, and conducts electricity?

Back 2

metal

Front 3

what type of material is known to be very brittle and an insulator?

Back 3

ceramic

Front 4

what type of material usually expands a lot and is less stable that the others?

Back 4

polymer

Front 5

what type of material is a physical mixture of 2 dissimilar materials?

Back 5

composite

Front 6

what 4 things define the structure of materials?

Back 6

arrangment
bonding
composition
defects

Front 7

what can dominate the behavior of a material?

Back 7

defects

Front 8

what property is related to structure and bonding?

Back 8

physical

Front 9

what property is related to deformation, and the application of load?

Back 9

mechanical

Front 10

what property is related to reactivity (corrosion)?

Back 10

chemical

Front 11

which property is related to biocompatibility?

Back 11

biological

Front 12

in most cases if material is chemically stable it will also be _____?

Back 12

biocompatible

Front 13

at a greater distance there are _____ attractive forces

Back 13

weak

Front 14

at a near distance: ____ attract easily to _____

Back 14

electrons attract easily to nuclei

Front 15

at a close distance electrons do what?

Back 15

interact to reduce energy

Front 16

at a very close distance what happens with attractive/repulsive forces?

Back 16

positive charges of nuclei repel

Front 17

what is the shortest distance between 2 nuclei where the net force is zero?

Back 17

equilibrium bond distance

Front 18

what is the energy state at equilibrium?

Back 18

LOWEST energy state

Front 19

what is the definition of bond energy?

Back 19

the energy required to break apart 2 atoms

Front 20

what dictates the behavior of polymers when it comes to deformation?

Back 20

secondary bonds between polymer chains

Front 21

If you have a shallow curve in the energy vs. distance diagram what does this tell you?

Back 21

-weak bonded element
-little energy input to allow movement
-ex: polymer

Front 22

If you have a steep narrow curve in the energy vs distance diagram what does this tell you?

Back 22

-stiff material
-need a lot of energy for a little bit of movement
-ex. ceramic

Front 23

high bond energy means what for:
melting T
elastic modulus
chemical resistance
thermal expansion

Back 23

high melting T
high elastic modulus
high chemical resistance
low thermal expansion

Front 24

what is the rate of change in bond distance with an increase/decrease in temperature?

Back 24

CTE (thermal expansion coefficient)

Front 25

which bonds are stronger than metallic?

Back 25

covalent, ionic

Front 26

which primary bond is non directional and electrons are lost/gained?

Back 26

ionic

Front 27

which primary bonds are directional and share electrons?

Back 27

covalent

Front 28

which primary bond is non directional and there is sharing of electrons in a delocalized manner?

Back 28

metallic

Front 29

what predicts the degree of ionic vs covalent bonding based on valence electrons?

Back 29

theory of electronegativity

Front 30

which primary bonds occur when there is a greater than 1.7 difference in electronegativity?

Back 30

ionic

Front 31

what is the secondary bonding due to permanent local dipoles?

Back 31

hydrogen bonding

Front 32

what is the secondary bonding that is a combination of covalent/ionic?

Back 32

chelation

Front 33

what bonding is between organometallic complexes (between 2 different solids)?

Back 33

chelation

Front 34

what are examples of chelation bonding?

Back 34

polymers to tooth
porcelain to metal
bacteria to dental materials

Front 35

total energy of a system is ____ by crystallization?

Back 35

decreased (lowest energy state)

Front 36

T/F crystalline structure is a high energy state

Back 36

false
lowest energy state

Front 37

what types of materials usually crystallize and which dont?

Back 37

metals crystallize
ceramics, polymers dont crystallize easily

Front 38

crystalline structure depends on what 3 things?

Back 38

time
temperature
symmetry

Front 39

what are structural imperfections?

Back 39

defects

Front 40

T/F defects are always present

Back 40

true

Front 41

what is the defect defined by an extra/missing atom?

Back 41

point

Front 42

what defect allows for plastic deformation?

Back 42

line

Front 43

what type of defect is a dislocation?

Back 43

line

Front 44

what type of defect is a grain boundary?

Back 44

area

Front 45

what type of defect is a big problem in dentistry?

Back 45

volume

Front 46

what type of defect is cracks, holes, and voids?

Back 46

volume

Front 47

what type of point defect has a missing atom at a certain crystal lattice position?

Back 47

vacancies

Front 48

what type of point defect has substitutions of a dissimilar atom in a crystal lattice?

Back 48

substitutional

Front 49

what type of point defect has a dissimilar atom in an interstitial position?

Back 49

interstitial

Front 50

what type of materials have grain boundaries(area defects)?

Back 50

all metals, some ceramics

Front 51

which defect is caused by the direction of the lattice abruptly changing, or at the point where two crystals meet?

Back 51

area defect

Front 52

T/F concentration is the lowest at grain boundaries

Back 52

false
-concentration is HIGHEST

Front 53

T/F volume defects can only be internal

Back 53

FALSE
-can be internal and external

Front 54

physical properties are defined by what two things?

Back 54

atomic structure
bonding

Front 55

what are the 6 physical properties?

Back 55

elastic modulus
CTE
melting T
optical/electrical properties
density
viscosity

Front 56

what are the units for thermal expansion?

Back 56

ppm/C

Front 57

what is the change in volume per change in temperature?

Back 57

thermal expansion

Front 58

equation for thermal expansion

Back 58

(change in length/original length) / change in temperature

Front 59

what is the thermal expansion for ceramics?

Back 59

1-15 ppm/C

Front 60

what is the thermal expansion for metals?

Back 60

10-30 ppm/C

Front 61

what is the thermal expansion for polymers?

Back 61

30-600 ppm/C

Front 62

CTE for tooth structure?

Back 62

9-11 ppm/C

Front 63

CTE for amalgam?

Back 63

25 ppm/C

Front 64

CTE for posterior and anterior composite?

Back 64

posterior-25-35
anterior-35-45

Front 65

dental amalagam percolation is caused by what?

Back 65

CTE mismatch

Front 66

what is PFM tensions?

Back 66

the tension caused by the mismatch in thermal expansion (want the porcelain to be under compression)

Front 67

CTE for PFM?

Back 67

14 ppm/C

Front 68

the bending and rebending of a paper clip till it snaps is an example of?

Back 68

thermal fatigue

Front 69

what is the external load or stress that can be supported to the point of fracture or failure?

Back 69

ultimate strength (fracture strength)

Front 70

what is reversible, temporary upon removal of applied stress?

Back 70

elastic deformation

Front 71

what is the external load or stress that can be supported to the point of fracture or failure?

Back 71

ultimate strength (fracture strength)

Front 72

what is reversible, temporary upon removal of applied stress?

Back 72

elastic deformation

Front 73

what is irreversible, permanent even when stress is removed?

Back 73

plastic deformation

Front 74

brittle materials only undergo what type deformation?

Back 74

elastic

Front 75

ductile materials undergo ___ then ___ deformation

Back 75

elastic then plastic

Front 76

T/F only tension and shear loading happen orally.

Back 76

false
-all loading happen in the teeth

Front 77

what type of loading is two forces directed toward each other?

Back 77

compression

Front 78

what type of loading is two forces directed away from each other?

Back 78

tension

Front 79

what type of loading is two forces directed toward each other and sliding past each other (scissor)?

Back 79

shear

Front 80

what load is twisting of an object due to torque?

Back 80

torsion

Front 81

clothes on a rod is an example of what type of load?

Back 81

flexure

Front 82

what type of load is not found in the real world, mostly for the lab?

Back 82

diametral tension

Front 83

what is load divided by cross sectional area?

Back 83

stress

Front 84

P/A is the equation for?

Back 84

stress (σ )

Front 85

what is the equation for stress?

Back 85

σ = P/A

Front 86

what is the maximum stress before failure?

Back 86

STRENGTH

Front 87

what is the equation for strain?

Back 87

ε = ΔL/Lo
(change in length/original length)

Front 88

total strain is the sum of ?

Back 88

elastic strain + plastic strain

Front 89

what part of the stress strain diagram is straight?

Back 89

elastic deformation

Front 90

what is the maximum stress point that a material can withstand before permanent deformation?

Back 90

elastic limit( proportional limit, yield strength)

Front 91

what is the slope of the stress strain diagram?

Back 91

elastic modulus (E)

Front 92

what is the first point beyond the proportional limit when deformation begins?

Back 92

yield point

Front 93

what is the point where the material fractures?

Back 93

failure point

Front 94

what is the last point of the stress strain curve?

Back 94

fracture strength/ultimate strength

Front 95

what is Hookes law?

Back 95

σ = Eε
stress=elastic modulus x strain

Front 96

elastic modulus (E) = ?
(according to hookes law)

Back 96

σ/ε
stress/strain

Front 97

what is the inherent resistance to flaw propagation?

Back 97

toughness

Front 98

what is shown by the area under the stress strain curve?

Back 98

toughness(till point of fracture)

Front 99

what is the area under the stress strain curve until the elastic limit?

Back 99

resilience

Front 100

what strain is completely recoverable?

Back 100

elastic

Front 101

what is the relative resistance to the onset of plastic deformation?

Back 101

hardness

Front 102

if you have increase hardness=___ yield strength

Back 102

increase yield strength
-harder to plastically deform

Front 103

what is a single cycle of loading?

Back 103

static

Front 104

what is a cyclic form of loading?

Back 104

dynamic

Front 105

if you load something at a fast rate the material will act?

Back 105

more brittle (stiff)

Front 106

fast strain rates increase resistance to?

Back 106

elastic and plastic deformation

Front 107

what is it called when there is a fixed strain and stress relaxes?

Back 107

stress relaxation

Front 108

what is it called when there is a fixed stress and strain relaxes?

Back 108

creep

Front 109

T/F in creep there is a physical distortion to accomodate stress

Back 109

true

Front 110

when athletes tear ligaments with quick movements is an example of what?

Back 110

fast loading that causes them to act more brittle

Front 111

if you load something slowly below the elastic limit it will act?

Back 111

more ductile

Front 112

what is the breaking or fracture caused by repeated cycling to stress below elastic limit?

Back 112

fatigue

Front 113

what is the limit below which the material will never fail under an infinite amount of cycles?

Back 113

endurance limit

Front 114

T/F sharp angles decrease stress

Back 114

false
they magnify stress

Front 115

what is it called when something is biologically compatible by not producing a toxic,injurious, or immunological response in living tissue?

Back 115

biocompatibility

Front 116

if something is toxic it is usually a ___ problem?

Back 116

chemical

Front 117

if something is an irritant it is a ____ problem?

Back 117

physical

Front 118

the fact that everyones immune system is different can cause some things to be _____.

Back 118

allergens

Front 119

what is it called when there is inflammation of the adjacent tissue (usually gingiva, mucosa, pulp etc)

Back 119

local reaction

Front 120

systemic reactions usually show up as?

Back 120

allergic skin reactions

Front 121

what is it called when the immune system becomes hypersensitive to an antigen with repeated exposure?

Back 121

sensitized

Front 122

if the reaction is 24 hours and reversible?

Back 122

acute

Front 123

if the reaction is 3 months and usually irreversible?

Back 123

chronic

Front 124

what is it called when something causes a toxic effect at the cellular level, but doesnt have to mean cell death

Back 124

cytotoxicity
(1st step in lab testing)

Front 125

what is the term when a test has comparable data within a lab (results turn out the same)

Back 125

repeatibility

Front 126

what is the term when a test has comparable data among multiple labs (will other people get the same result

Back 126

reproducibility

Front 127

which testing is cheap, fast, more reproducible, and more humane?

Back 127

in vitro (petri dish)

Front 128

which testing evaluates complex systemic interactions, is more relevant to human response, expensive and time consuming?

Back 128

in vivo (animal/human testing)

Front 129

what material do dentist often become sensitized to?

Back 129

methacrylates

Front 130

what material are women much more sensitive to then men?

Back 130

nickel

Front 131

what material can cause more problem for dentist than patient because we are exposed to vapors during placement?

Back 131

amalgam

Front 132

what can cause soft tissue irritation and pain, transient (day->week)

Back 132

bonding agent

Front 133

what can be cytotoxic to vital teeth and cause cause transient sensitivity?

Back 133

dental bleaching

Front 134

what is the difference between a metal and metal alloy?

Back 134

metal-single element
alloy-chemical mixture of two or more elements

Front 135

what is a slang method for reporting purity?

Back 135

nines

Front 136

4 nines purity?

Back 136

99.99% pure

Front 137

a proportional method of reporting the amount of noble metal content in an alloy?

Back 137

karat

Front 138

24 kt?

Back 138

100%

Front 139

1000 fine

Back 139

100%

Front 140

what is the method of pouring molten liquid and using centrifugation to form a very individual and unique shape?

Back 140

casting

Front 141

what is chemical formula of iron?

Back 141

Fe
-rusts and malleable

Front 142

what is the chemical formula of steel?

Back 142

Fe +C
-stronger than iron

Front 143

what is the chemical formula of stainless steel?

Back 143

Fe + C + Cr

Front 144

dental instruments are usually made of ?

Back 144

stainless steel

Front 145

316 L steel means?

Back 145

L=low carbon .03
16= 16-18% Cr

Front 146

what does the Cr do for stainless steel?

Back 146

it reacts with oxygen on the surface to form Cr oxide which is a film to protect it against corrosion

Front 147

what is the resistance to plastic deformation?

Back 147

hardness

Front 148

what is it called when you increase the elastic limit (increase difficulty for plastic deformation?

Back 148

hardening

Front 149

what is the process where you add a second element to the primary to perturb the lattice?

Back 149

solid solution hardening

Front 150

what is it called when you cause movements of the dislocations and they eliminate or pile up?

Back 150

work hardening (strain hardening)

Front 151

what is the process where you add something chemically that precipitates out and fills spaces between crystals?

Back 151

precipitation hardening
ex. FeC in steel

Front 152

what is the rapid cooling that prevents equilibrium phases from forming?

Back 152

quenching
(ex. stick sword in cold water after shaping it)

Front 153

what is holding at high temperatures for extended amount of time to approach equilibrium?

Back 153

annealing
(heat treatment to alter or control grain structure)

Front 154

what is age hardening?

Back 154

precipitation of a new phase with increasing temperature over time

Front 155

what is overaging?

Back 155

if you precipitate too much past the maximum hardness
(still harder than original structure)

Front 156

T/F excessive work hardening raises the recrystallization temperature?

Back 156

false
-lowers it

Front 157

what is plastic deformation around room temperature?

Back 157

cold working

Front 158

what is plastic deformation at high temperatures

Back 158

hot working

Front 159

recrystallization is a type of?

Back 159

annealing heat treatment

Front 160

what is the oxidation/reduction of materials when they are in direct contact?

Back 160

chemical corrosion

Front 161

what is it called when reactants are separated but connected in a circuit?

Back 161

electrochemical corrosion

Front 162

electrochemical corrosion cell is made of what 4 things?

Back 162

anode-oxidized
cathode-reduced
electrolyte-solution
circuit: connects two like wire

Front 163

T/F can have corrosion between any two metals with different oxidative potentials and in contact with each other

Back 163

true

Front 164

T/F anodes have positive electrochemical potential

Back 164

false
-negative

Front 165

what is the term for no reaction when it comes to corrosion?

Back 165

immune
ex. gold

Front 166

what is the term for continuing reaction when it comes to corrosion?

Back 166

active
ex. iron, steel

Front 167

what is the term for active but then stopping when it comes to corrosion?

Back 167

passive
ex. SS,COCr, Ti

Front 168

What are 3 examples of things that form protective oxide films on surface?

Back 168

stainless steel
CoCr
Ti

Front 169

change in electrochemical potential, temperature, pH and PO2 can all affect?

Back 169

corrosion rate

Front 170

what is the corrosion when two different metals make contact?

Back 170

galvanic

Front 171

corrosion that occurs in alloy with multiple phases?

Back 171

local galvanic corrosion

Front 172

corrosion that occurs in different electrolytes?

Back 172

crevice corrosion

Front 173

corrosion that occurs in stressed regions?

Back 173

stress corrosion