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AU13 Operative Afternoon Lectures > BioMaterials > Flashcards

BioMaterials Flashcards

0
Q

A material used to construct artificial organs, rehabilitation devices, or prostheses and replace natural body tissues, without causing any hard or negative reactions

A

Biomaterials

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1
Q

What are the three main classes of materials

A

Metals
Polymers
Ceramics

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2
Q

Mechanical properties of metal (3)

A

Hard
Ductile/tough
Strong

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3
Q 
Bonding of metals: 
metallic elements have \_\_-\_\_ electrons in outer shell
Electrons are key to \_\_\_\_\_\_\_\_\_\_\_
Electrons are \_\_\_\_\_\_\_\_ bound to nucleus
Electrons have \_\_\_\_\_ mobility
A

1-3
key to metallic bonds
loosely
free mobility

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4
Q

What is the microstructure of pure metals (4)

A

Molten metal –> nuclei of crystallization –> crystal growth —> formation of crystal grains

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5
Q

Polycrystalline structures = pure _____

A

Metals

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6
Q

Thermal properties of metals

A

High processing temperature (except amalgam)

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7
Q

Metal alloys are processed for __________ and __________

Alloys are ______ and _____ ductile than pure metals

A

Cast metals for crowns and amalagms

Stronger and less ductile

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8
Q

Mechanical properties of ceramics (3)

A

Hard
Brittle
Strong

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9
Q

Bonding of ceramics via _____ and _______ bonds

Both are stronger than _______ bonds

A

Covalent and ionic

Metallic

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10
Q

Electron donor and acceptor

Weaker

A

Ionic bonds

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11
Q

Equally share electrons; non mobile ions

A

Covalent bonds

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12
Q

Thermal properties of ceramics

A

High processing temperature except cements

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13
Q

How ceramics are processed

A

Indirect placement

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14
Q

Microstructure of ceramics:
Mixture of _______ and ___________ elements
Most common ceramics in dentistry are 3 metal oxides….
_____ is a tetrahedron

A

Metallic and non-metallic
Most common ceramics: SiO2, Al2O3, K2O
SiO2 is the tetrahedron

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15
Q

Microstructure of ceramics:
Crystalline (long range order), crystalline silicate-_____, or _________; and ________
Crystalline (short range order) or amorphous silicate (______)
Most dental ceramics are ___________ or ______________

A

Silicate-quartz, crystobilite; and leucite
Glass
Semicrystalline or polycrystalline

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16
Q

Mechanical properties of polymers (3)

A

Soft
Ductile/tough
Weak

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17
Q

Bonding of polymers:
_________ bonds
High _______ weight
Long molecules composed of _________ elements and ________ elements (COHN)
Polymers are entangled in ______ chains
Derive strength and properties from ___________

A 
Covalent
Molecular
Nonmetallic and organic
Long
Entanglement
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18
Q

Thermal properties of polymers

A

Lower processing temp except indirect composites

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19
Q

Processing of polymers:
Used as _______ processing materials
_________ placement
Polymerization; ___________ —-> _____________

A

Direct
Direct
Monomers –> polymers

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20
Q

Steps of polymerization (4)

A
  1. Activation - production of free radicals
  2. Initiation - free radical combination with a monomer unit to create the beginning of a growing chain; double bond opening
  3. Propagation - continued addition of monomer units
  4. Termination - cancellation of growing chain end by any one several possible events
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21
Q

What factors contribute to each materials mechanical properties (4)

A

atomic rearrangements (crystalline vs non-crystalline)
bonding
composition
defects

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22
Q

polymerization can be initiated by theses three things

A

light
heat
chemical mixing

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23
Q

ability to slide chains by each other

A

linear polymer (monomethacrylates)

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24
Q

covalent bonds; stronger and more brittle
limits movement
will not dissolve

A

cross-linked polymer (dimethacrylate)

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25
Q

physical mixture of metals, ceramics, and/or polymers

A

composite

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26
Q

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

A

Rule of Mixtures

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27
Q

chemically bonded to resin phase (matrix) to improve properties

A

fillers

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28
Q

relative rate of change during temperature changes

A

coefficient of thermal expansion

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29
Q

Materials (teeth, amalgam, composite, etc) have ___________ coefficients of thermal expansion, inducing ________ which is the ingress or egress of fluid at the marginal level

A

different

perlocation - fluid can leak into margin from separated amalgam

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30
Q

Teeth are ______ due to high mineral content

dental pulps can withstand small temperature changes over _____ times

A

insulators

short

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31
Q

metals have a _____ thermal conductivity so they need a _____-like base before placement

A

high

insulator

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32
Q

composites have a _____ thermal conductivity and do not need a base

A

low

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33
Q

defined on a 3D coordinate system

A

Color;

value (intensity), hue (wavelength), and chroma (purity)

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34
Q

material may have a different color under a different light source

A

metamerism

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35
Q

Disposal of Amalgam;
use _____-use capsules
use a ____-touch system when cleaning spills
discard old or damaged capsules that are prone to leaking
store amalgam in a _____ space with finely divided _____
avoid ________ heating

A

single
no
cool; sulfur
baseboard

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36
Q

Patient Issues with Amalgam;
some patients may exhibit ________ _____ _______
many _________ are used

A

allergic skin reaction

alternatives

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37
Q

Operator Issues with Amalgam;
routes of mercury exposure: ____ contact, _____ of vapor, and ______ droplets
threshold limit value; ____ mgHg/m3

A

skin contact, inhalation of vapor, airborne droplets

0.05 mgHg/m3

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38
Q

dental amalgams are any alloy made of Hg with a _____-____ alloy with varying amounts of ____ and small amounts of zinc

A

silver-tin
copper
zinc

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39
Q

Benefits of high copper amalgam (4)

A

greater clinical longevity
lower creep values
corrosion resistance
contains >12%

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40
Q

Zinc-containing vs zinc free (3)

A

zinc facilitates lathe-cut particles
improves corrosive resistance
no concern with Zn-free alloys about moisture contamination

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41
Q

Mercury to Alloy ratio

A

0.05, but depends of manufacturer

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42
Q

Silver –> Hg

major reaction phase in both high and low copper amalgam

A

Gamma 1 (product)

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43
Q

Tin —> Hg

only seen in low copper amalgam

A

Gamma 2 (product)

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44
Q

gamma is the _____ material + Hg –> reaction phases (____) + _______ alloy particles (core)

A

starting alloy particles
matrix
unreacted

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45
Q

first step in setting process of amalgam

A

both gamma 1 and gamma 2

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46
Q

second step in setting process of amalgam

A

disappearance of gamma 2, and formation of n’ phase

slower setting reaction than for HCSS products because of this second step

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47
Q

general characteristics of amalgam (4)

A

brittle under normal rates of loading (higher compressive (350) to tensile (70) strength)
poor edge strength
insufficient strength of set amalgam would increase amount of marginal breakdown
no free Hg in final set

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48
Q

the deformation that occurs as a result of constant force (load) on something; the force won’t cause an immediate break, but will create deformation over time: low copper has the highest level

A

creep

blocked by high n’ value in high Cu values

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49
Q

clinical advantages of amalgam (4)

A

margin sealing capability (decreases micro-leakage over time)
corrosion products
easily prepared direct restorative material
relatively inexpensive compared with gold alloy

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50
Q

Alloy particles have complex structure with three phases

A

γ(Ag3Sn) β(Ag-Sn) ε(Cu3Sn)

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51
Q

lathe cut

A

creates a wide range of sizes

from cast ingot

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52
Q

corrosion at inter proximal contact with gold alloys

A

galvanic corrosion

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53
Q

corrosion due to multiple phases
anode (corroding metal) and cathode (different metal) [2 different phases in amalgam]
ionic movement

A

electrochemical corrosion

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54
Q

corrosion at margins

A

crevice corrosion

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55
Q

corrosion from reaction with sulfide ions at occlusal surface
lower pH and oxygen concentration, and retained under plaque due to lower oxygen levels

A

chemical corrosion

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56
Q

measure of surface properties via contact angle used to measure how liquid interacts with solid
good wetting = _________
poor wetting = _________

A

good wetting = low contact angle (approach 0)

poor wetting = high contact angle (approach 180)

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57
Q

wetting can be anticipated on the basis of _______ and ________ of materials

A

hydrophobicity and hydrophilicity

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58
Q

allow penetration into areas with water
usually mixed with solvent (alcohol/acetone)
very low viscosity
allows for attachment to composite

A

hydrophilic fibers

59
Q

angle where a liquid interference meets a solid surface

A

contact angle

60
Q

ability of a liquid to maintain contact with surface

A

wet-ability

61
Q

molecules can have _____ hydrophobic and hydrophilic properties

A

both

62
Q

spontaneous destructive oxidation of metals (all metals do this)

A

corrosion

63
Q

immune to corrosion

A

noble metals, like gold

64
Q

produces a corrosive film that prevents further corrosion

titanium implants

A

Passive corrosion

65
Q

normally occurs through dissolution of oxides created by H-bonding; effects of water in local areas of high acidity

A

chemical dissolution (corrosion/hydrolysis) of ceramics

66
Q

absorption of water into the _______ (secondary bonds), causes a _________ change
hydrolytic degradation and release of components (primary bonds)
-water, enzymes, bacterial byproducts

A

polymers

dimensional

67
Q

degradation products are related to

A

toxicity

68
Q

Stress-Strain Curve
x axis = _____
y axis = _____
linear portion = _____

A

strain
stress
modulus

69
Q

represents the amount of strain (deformation) process in response to each amount of stress (load)
overall stiffness of a material
higher slope = can under go ____ stress

A

modulus (linear portion of stress-strain curve)
more stress
can handle more stress per strain

70
Q

point on modulus from which the line starts to curve, and begin to irreversibly deform

A

elastic limit

71
Q

area under curve to point of elastic strain (reversible deformation)

A

resilience

72
Q

area under curve to point of fracture due to plastic strain (irreversible deformation)

A

toughness

73
Q

_____ a material will cause the material to become soft and the mechanical property value decreases
stress-strain curve will shift to the _____ and ______

A

heating

right and downward

74
Q

multiple cycles of low stress

A

fatigue

75
Q

measures a materials resistance to crack propagation
has high clinical correlation to clinical wear data
the amount of resistance to breakage when a crack in a sample is pulled apart

A

fracture toughness

76
Q

create small cracks at one area, which eventually causes breakage at that point

A

cyclic stress

77
Q

study of stress and strains

effects of forces on the motion of biomaterials and biologic structures

A

biomechanics

78
Q

teeth are not completely ______, can lead to abfraction

A

rigid

79
Q

________-______ stability due to enamel on sound dentin

when a tooth is unrestored, it is very strong

A

buccal-lingual

80
Q

when the enamel wall is no longer ______, its resistance to fracture is much lower
AKA ________ weaken teeth

A

continuous

preparations

81
Q

esthetic direct restorative
cured by visible light
primary benefit is the combination of esthetics and ease of placement
hydrophobic - promotes bonding
moderate clinical outcomes
is a hybrid material of organic and inorganic phases ( ____ and ____)

A

composites

resin and filler

82
Q

components of a composite resin (4)

A

organic resin phase
inorganic filler phase
bonding agent
visible light initiator

83
Q

helps with the processing and handling of composites
BISGMA provides physical properties
viscosity high and cannot be used alone

A

resin

84
Q

helps modulus and wear resistance

A

filler

85
Q

trade offs of composite resins;
wear resistance and strength but ____ and has ___ processing
poor wear resistance but ___ with ____ processing

A

brittle, poor

tough, good

86
Q

joining of polymers with covalent linkages

A

cross linking

87
Q

additional _____ lead to a stiffer and stronger material
longer working time
curing develops mechanical properties
increases modulus
also depends on the materials you started with (stiff becomes stiffer)

A

cross-links

88
Q

different ____ sizes exist and control properties
silica or zinc inorganics
50-80% weight of composite
has surface -OH groups

A

filler

89
Q 
higher filler loading results in a
\_\_\_\_\_\_ modulus,
\_\_\_\_\_\_ strength
\_\_\_\_\_\_ viscosity
\_\_\_\_\_\_ in shrinkage
A

increase
increase
increase
decrease

90
Q

why fillers are small (5)

A

different sizes (micro, nano, micron, etc)
teeth are nano composites
smaller fillers have better wear properties
allows for better polishing and finish
expectation of better mechanical properties

91
Q

binds inorganic filler so filler can bind to organic resin
uses the OH group on filler
forms chemical bridge

A

coupling agent

92
Q

results from a density change of monomer to polymer

A

polymerization shrinkage

93
Q

properties of polymerization shrinkage (4)

A

inherent property of double bond polymerization
measures by density change
important for direct composite restoratives
important for any material that requires dimensional stability

94
Q

clinical consequences of shrinkage (2)

A

causes stress on tooth structure

can cause micro leaks and lead to secondary caries

95
Q

2 components of glass-ionomer cements

A

acidic polymer and aqueous (water) solution (polyacid)
basic glass (aluminaflurosilicate)
+ a modifier

96
Q

properties of glass ionomers (4)

A

cured by acid base reaction
releases fluoride
good adhesion to tooth structure
salt bridges created slide, Al3+ can bind to 3 groups

97
Q

curing reaction of glass ionomers (5)

A
  • polyacid reacts with basic glass, glass releases Ca2+, Al3+, F-
  • divalent Ca2+ ions quickly chelate with acid polymer chains
  • not all the glass is consumed in reaction
  • salt bridges (COO-) form from the polyacid and glass (Ca and Al)
  • Al3+ replaces Ca2+, increasing strength and releasing F-
98
Q

how GI reaction differs from composite

A

no coupling agent needed
F- released
mechanisms not clearly understood
water based restorative

99
Q

important for forming a mechanical bond as opposed to a chemical bond

A

microtags

100
Q 
based upon composite resin chemistry
contains acids groups to promote bonding
dimethacrylates that are visible light cured
unfilled or lightly filled
bind to enamel
hydrophilic
A

adhesives

101
Q

differences between adhesives and composites (2)

A

lower level of filler to decrease viscosity in adhesives

additives in adhesives that help in bonding

102
Q

both hydrophobic and hydrophilic properties are needed because composites are _______ and enamel/dentin is _________

A

hydrophobic

hydrophilic

103
Q

designed to flow into pits
prevents further decay
etching recommended to prepare enamel

A

sealants

104
Q

differences between sealants and composites (3)

A

there is no filler, but otherwise the same chemistry
low viscosity, allows for easy pit flowing
prevents further decay

105
Q

oxygen interferes with radical polymerization (inhibiting the polymerization of methacrylates)
at surface of composites or sealants, unpolymerized material must be removed
surface of VLC materials are often uncured

A

oxygen inhibition layer

106
Q

used to make a negative mold of dental structures

transfer to gypsum model (plaster/stone)

A

impression materials

107
Q 
used for making an impression
water based
resembles a solution, but made up of colloidal particles dispersed in a liquid
calcium cross-linked
temperature controlled (reversible)
chemically controlled (irreversible)
A

irreversible hydrocolloid (alginate)

108
Q

hydrophobic, synthetic impression materials

polysulfides, siloxane, polyethers

A

viscoelastic

109
Q

ideal properties of impression materials (6)

A 
low cost
long shelf life
biocompatible
pleasant to patient
dimensionally stable
good handling properties
110
Q

advantages of alginate being water based (7)

A 
economical
easy to use
quick setting
fair taste
hydrophobic
displaces blood/saliva
stock trays
111
Q

disadvantages of alginate being water based (5)

A 
limited detail reproduction
low tear resistance
single pour only
quick pouring required
low dimensional stability
112
Q

inherently hydrophobic, but addition type can be made hydrophilic
condensation type was first introduced
hydrophobic but chemically and dimensionally stable
cross-linked by hydrosilation reaction
hydrophobicity may lead to voids when stone added

A

polysiloxanes

113
Q

polysiloxanes can be made hydrophilic by simple addition of a ________ or chemical incorporation go hydrophilic moieties into _________ backbone

A

surfactant

silicone

114
Q

improve detail registration and detail transfer for polysiloxanes - makes more hydrophilic

A

surfactants (can also use polyethers)

115
Q 
hydrophobic, but more hydrophilic than polysiloxanes
bad tasting
adhesives work well
good dimensional stability
fast stting
stiff and low tear strength
A

polyethers

116
Q

dehydrated form of calcium sulfate

A

gypsum materials

117
Q

process of driving off water of calcium sulfate hemihydrate to form gypsum
gives rise to differences in gypsum materials
straightforward and reversible reaction
heat is released (exothermic)

A

calincation

118
Q

when setting, growth and subsequent interlocking of gypsum _______ occurs
contributes to _______ and dimensional change
physical and mechanical properties can be influenced by differences of these

A

crystals

strength

119
Q

gypsum properties dependent on _________ and _________ structure

A

density and crystal structure

120
Q

dental stone used for ______, not plaster

A

models

121
Q

dense, regularly shaped, relatively nonporous cubodial crystal material
requires less water and is 2.5x stronger than plaster
widely used in cast making and molds requiring high crushing strength and abrasion resistance

A

dental stone

122
Q

______ based materials have to last a long time
have a filler and dimethacrylate that cross links
provisional are normally temporary

A

denture

123
Q

denture base is normally ______ cured

TRIAD is a custom tray material and is also _____

A

VLC

visibly light cured

124
Q

provisional materials are normally ________ cured
similar to TRIAD cold cure not light cure
curing achieved by mixing

A

chemically

125
Q

designed to absorb impact
high toughness, low rigidity
thermoplastic materials
can be melted or pressure processed

A

mouthguards

126
Q

low softening point
thermally processed with hot water
vacuum formed - requires a dye

A

thermoplastic polymer

127
Q

designed to absorb impact
high toughness, low rigidity
can’t be melt of pressure processed

A

copolymer controls properties

128
Q

used to bind restoration of appliances to tooth structure

A

cements

129
Q

glass ionomers
resin modified glass ionomers
zinc phosphates
zinc polyacrylate

A

water based cements

130
Q

composites and compounds

A

resin based cements

131
Q

zinc oxide eugenol

A

oil based cements

132
Q

requirements for cements (2)

A

low viscosity but good mechanical properties

25um thickness

133
Q

how to balance the mechanical properties and viscosity of water based cements

A

adjust powder-liquid ratio
[powder = filler]
more filler = more viscosity = more modulus
low P:L ratio increases working time and setting time

134
Q

resin cements are typical a one component system
viscosity and strength controlled by ______ loading
also by _____ molecular weight monomers
increased filler loading = increased ____ and ____
ortho bonding needs to be reversible
similar to composite resins

A

filler
low
viscosity and modulus

135
Q

advantages of glass ionomers (5)

A 
adheres to tooth structure
fluoride release
clinical record of retention (better than composite)
dimensionally stable
biocompatible
136
Q

disadvantages of glass ionomers (5)

A 
slow setting
early dissolution
optical properties
stain resistance
poor physical properties
137
Q

protects pulp and minimizes post-op sensitivity
acts and thermal and chemical barrier
controls inflammation of pulp
controls fluid movement

A

liner and bases

138
Q

relatively thin layer of material used to protect dentin from residual reactants that diffuse out of the restrain or oral fluids that may penetrate leaky restoration interface; lower viscosity

A

liner

139
Q

provides thermal protection for the pulp to supplement mechanical support for the restoration by distributing local stress from the restoration across the underlying dental surface during amalgam condensation
requires greater mechanical properties
viscosity doesn’t matter

A

base

140
Q

defensive reparative dentin
15 days cell differentiates
30 days microscopic reparative dentin
15 days radiographic reparative dentin

A

pulp capping

141
Q

in ______ pulp capping, you apply a calcium hydroxide layer

A

direct

142
Q

zinc oxide eugenol (ZOE) - pain reduction = _______ ________

A

sedative restoration

143
Q 
intermediate restorative material
base and temporary - reinforced fillers, ZnO powder, 
oil of clove (dulls pain)
expands when set-seals
can use under a composite
inhibits polymerization
A

reinforced zinc oxide eugenol (ZOE)

144
Q 
temporary materials
melts at a lower temperature
carve-able
burns off
dimensionally stable
lower molecular weight in-between polymers and organic liquids
A

waxes

145
Q

Low Cu amalgam doesn’t have a ______ phase, so therefore creep is more prevalent

A

N’

146
Q

Cu6Sn5 is the ________ phase

It prevents the sliding of gamma 1 thus minimizing creep and marginal breakdown

A

n’ phase

AU13 Operative Afternoon Lectures (1 decks)

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