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Dental material > Dental pt4 > Flashcards

Dental pt4 Flashcards

1
Q

polymer

A

chain molecule many units

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2
Q

olymer

A

short polymer 2,3,4 mers units

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3
Q

mer

A

simplest repeating chem units -> make up polymer

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4
Q

monomer

A

molecule forms polymer

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5
Q

Polymerization

A

mono forms poly thru primary covalent bond

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6
Q

Copoly

A

2/more diff mono joined
types: random, block

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7
Q

Molecular weight poly

A

sum MW mers made up
M= m+m+m

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8
Q

Degree polymerization

A

total mers/ poly

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9
Q

Spatial structure poly

A

linear
branched
cross linked

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10
Q

Effect heating on linear, branched molcule

A

weak, physical bonds
heating -> bonds break -> slide -> softened material -aka thermoplastic

Thermoplastic - heat -> softened ; cooling - hardened

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11
Q

Ex thermoplastic

A

polystyrene
polyvinyl acrylics
polymethyl methacrylate PMMA

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12
Q

Ex cross linked polymer

A

cis polyisoprene
cis bisphenol
cis silicones
cross linked PMMA

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13
Q

Charac cross linked polymer

A

strong covalent bond -> strong bonded unit

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14
Q

Effect heating on spatial molecule

A

NO chain sliding -> NO softening aka thermosets

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15
Q

Prop poly for strength, hardness, resistance

A

longer chain
higher molecular weight
many cross linked
-> poly increase strength, hardness, resistance creep along increase brittleness

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16
Q

Prop poly affected by

A

degree poly
no. cross linked chain
chem comp
amount crystallinity
plasticizer: add to stiff uncross -> reduce rigidity (small molecule surrounds big -> move easily) aka decrease Tg

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17
Q

Prop elastomeric impression

A

individual coiled chains
few cross links

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18
Q

Prop dental polymers

A

crystalline/ amorphous

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19
Q

Crystalline poly

A

atoms w/ reg arrangements

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20
Q

Charac crystalline

A

stronger
absorb < water

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21
Q

Charac amorphous poly

A

irreg arrangements

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22
Q

Glass transition temp def

A

temp range poly rigid glassy -> soft

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23
Q

Glass transition temp measured in terms of

A

stiffness
modulus

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24
Q

Temp < Tg

A

brittle

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25
Q

Temp > Tg

A

rubber

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26
Q

room temp&raquo_space;> Tg

A

elastomer
(memorize as in room temp aka room temp high - high Tg - elastomer)

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27
Q

room temp «< Tg

A

rigid
(memorize as in room temp - room temp low aka low Tg -> rigid)

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28
Q

Effect plasticizer

A

added to stiff uncross linked polymer -> reduce rigidity aka decrease Tg

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29
Q

How plasticizer effects

A

small molecules surrounds large -> large move more easily -> decrease Tg

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30
Q

Prop after poly

A

poly shrinkage
water absorption
warpage: change shape when heated
(unmono poly)

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31
Q

what cause poly shrinkage

A

mono in poly arranged at covalent bond distance aka < og distance unpoly mono

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32
Q

effect water absorption

A

expansion
HEMA hydrophil mono > tendency cause water absorption

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33
Q

effect unpoly mono

A

toxicity

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34
Q

Types poly

A

add. poly - free radical add. poly
condensation

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35
Q

Charac, ex, use add. poly

A

NO by product formed
ex:
PMMA - use: denture
bis GMA - use: matrix resin of composite

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36
Q

Charac condensation

A

form low MW by product (H2O/ OH)
ex:
polysufide
silicon rubber impression material

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37
Q

Free radical add. poly accelerated by

A

heat
light
small amount peroxides

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38
Q

Steps free radical add. poly

A

initiation:
produce free radical
forms activated mono

propagation:
radicals (activated mono) attacks = bond -> add. mono to free radical -> chain grows

termination:
inhibitors (hydroquinone) -> increase storage life -> reduce initiation -> forms branches, cross links

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39
Q

Initiaion step in free radial add. poly

A

produce free radical
initiator:
1. Thermal initiator
have 1 weak bond -> breaks at high rate - moderate temp -> free radicals (peroxides O-O / azo N=N)
2. Photo dissociation
UV light -> breaks bond -> radical
3. Redox rxn
transfer e- -> radical

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40
Q

Poly in dentistry

A

denture base poly

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41
Q

Def denture base

A

material which teeth of denture are set -> rests on supporting tissue when denture in mouth

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42
Q

Component denture base poly

A

simple stiff base w/ teeth
stiff base + resilent liner

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43
Q

ad of resilent liner + stiff base

A

greater retention, comfort

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44
Q

When to use viscoelastic gel aka tissue conditioner

A

tissue under loose denture traumatized b/c constant motion hard plastic over mucosa

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45
Q

Classification denture, soft liners, tissue conditioners

A
  1. Denture based material
    - heat cured (conventional, high impact)
    - autopoly PMMA
    - injection molded
  2. Soft liners
    - acrylic
    - silicon (room temp vulcanizing RTV, heat cured
  3. Tissue conditioners
    - plasticized acrylics
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46
Q

Heat cured denture base material component powder, liquid: initiator, chem accelerator, filler, plasticizer, opacifier, inhibitor

A

(starting -> faster -> more -> flexibility -> opaque, stoping)

powder:
-poly beads PMMA polymethyl metacrylate (poly)
-benzoyl peroxide (initiator)
-inorg glass beads/ beads coupling agent Triydroxy -Silane
-dibutyl pthalate (plasticizer)
-Zn
-Mercuric Cadmium Sulfate (pigments) - colored nylon fibers -> stimulate blood vessels

(powder in heat -> NO run -> NO accelerator -> No one stop it -> NO inhibitor)
(heat -> started by using benzoyl peroxide -> see Lane? -> Silane -> Zack makes it opaque (Zn - opacifier) -

liquid:
-mono beads MMA methyl metacrylate
-dibutyl pthalate (plasticizer)
-3rd amine/ sulfinic acid
-hydroquinone
-cross linking agent w/ reactive CR=CR group opposite ends molecules (reduce denture base solubility to org solvents ; reduce craze)

(plasticizer + cross linking agent and things powder dont have -> plasticizer + chem accelerator + inhibitor)

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47
Q

Powder liquid rxn poly

A

powder liquid -> dough -> MMA (mono) into PMMA (poly) -> swell -> entanglements btw poly -> bead-monomer mixture cohesive gel -> benzol peroxide diffuse out bead -> interstitial space -> benzoyl peroxide initiates dough curing

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48
Q

Cond poly to convert to solid

A

min length 5000 beads
MW 150k

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49
Q

Effect of improper hardening heat cured

A

weakens material
distortion -> trauma to soft tissue
swelling
poor adhesion denture
discoloration

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50
Q

Autopoly/ pour type PMMA denture based materials charac

A

similar to heat cured denture
but have reducing agent (3rd aromatic amine)

(auto turn on gas but need agent -> auto same as heat but need RD agent)

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51
Q

Effect reducing agent on autopoly

A

mono + reducing agent (3rd aromatic amine) + benzoyl peroxide at room temp -> peroxy free radicals -> initiate free radical poly

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52
Q

Cond of autopoly

A

size, MW, plasticizer content balanced -> high penetration mono into bead w/o too early increase viscosity -> allow pouring acrylic into mold, good wetting plastic teeth

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53
Q

Ad, disad Injection denture based materials

A

Ad:
constant MW
replacement metal denture for patient sensitized methacrylate/ Ni/ Co (ỊNection -> meth -> methacrylate ; in -> ni -> Ni)
high flexibility
Disad:
high cost
low craze (heat) resistance - b/c NO crosslinks
low teeth adhesion

(injection -> expensive -> no need heat -> low craxe resistance -> if injection too much -> no teeth aka low teeth adhesion)

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54
Q

Types injection denture based material

A

low MW linear PMMA
Polycarbonate
Nylon (Sunflex) and Polyamid

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55
Q

Light activated material components

A

UDMA urethane dimethtacrylate
Silica filler
(U LIGHT up the world SILLY-> light - UDMA - sillica)

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56
Q

Steps light activated material components

A

form base plates -> light chamber 400-500nm

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57
Q

Ad, disad light activated material components

A

Ad: quick
Disad: expensive

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58
Q

def, func soft liners

A

resilient (elasticity) poly
replace fitting surface hard plastic denture
improve retention denture

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59
Q

Types soft liners

A

permanent soft liners (acrylic, silicon)
temporary soft liners/ tissue conditioners

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60
Q

Permanent soft liners components

A

acrylic
silicone
(acrylic nails, silicon boobs are permanent)

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61
Q

Charac acrylic in permanent soft liners

A

highly plasticized aka Tg < oral temp
-> soft liner elastic in mouth
high dibutyl pthalate -> high HEMA made -> H2O absorbs -> swelling -> deform

(acrylic is plastic
-> high plasticizer -> high dibutyl pthalate -> high HEMA -> swelling -> deform

-> highly plasticized aka soft liner on mouth oral temp)

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62
Q

Types silicon soft liner

A

room temp vulcanizing RTV
heat cured

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63
Q

Disad silicon soft liner

A

poor tear resistance
NO adhesion acrylic denture base
high effect osmotic pressure

(silicon boobs -> NO tear -> NO adhesion acrylic nails -> flying planes -> osmotic pressure effect)

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64
Q

Temporary soft liners ex

A

PEMA - primarily acrylic gel
PMMA - polyethylmetaacrylate

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65
Q

Basic info alloy

A

elements alloyed tgt -> change prop -> single melting temp change to range temp - eq btw solid crystal nucleated in liquid metal

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66
Q

Liquidus temp

A

upper temp for liquid solid alloy range

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67
Q

Liquidous temp def

A

temp solid crystal dissolve during heating
temp solid crystal nucleate during cooling

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68
Q

Solidus temp def

A

temp point last liquid solidifies on cooling
last solid melts on heating

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69
Q

Formation alloy

A

cooling - liquid metal nucleate -> atoms joining crystal from packing arrangement in space characteristic of metal/ alloy at eq

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70
Q

unit cell

A

smallest division crystalline metal
repeated unit cell -> crystalline structure of crystalline solid
atom at each corner shared among adj 8 unit cells

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71
Q

Formation nucleation, polycrystalline grain structure

A

cooled melted metal -> cluster atoms forms solid crystal nuclei -> stable -> grow into crytsallites/ grains if E favorable
aka
if increase interfacial SA -> E lost by bonding > gain

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72
Q

Process nucleation

A

Homogeneous nucleation
Heterogeneous nucleation

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73
Q

Homogeneous nucleation

A

rapid cooling nuclei
-> > E loss when liquids bond solid
-> > nuclei formed/ unit volume -> form < size polycrystalline grains -> irregular polycrystaline grains

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74
Q

relationship nuclei, grain size

A

more nuclei formed - smaller grain size

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75
Q

Heterogeneous nucleation

A

add foreign solid particle (fine high melting metal/ oxide powder) in melted metal -> atoms attracted -> decrease grain size

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76
Q

Ad decrease grain size

A

increase yield stress
increase ductility
increase strength

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77
Q

Alloy def

A

2 metals form solution in liquid state -> atoms mix randomly

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78
Q

Combining metal for alloys cond

A

same atomic lattice type
similar atomic radii
same valence number
form bond to other atoms with strength similar to those form among themselves

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79
Q

Bravais lattice

A

14 diff grid structure for symmetry

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80
Q

Types structure

A

Face centered cubic FCC
Body centered cubic
Hexagon closed packes

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81
Q

Face centered cubic FCC example

A

Au
Al
Cu
Ni
(Face -> Apply All Completely Neck -> Au, Al, Cu, Ni)

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82
Q

Body centered cubic BCC

A

Fe
Cr
Mo
Ta
W
(body -> Fe Cr Mo Ta W)

83
Q

Hexagonal closed packed

A

Co
Ti
Mg
Cd
Zn

(Hex -> sounds bad -> mad -> Co Ti Mg Cd Zn)

84
Q

Methods ID crystalline structure

A

X ray diffraction
Electron diffraction
Neutron diffraction

85
Q

Single crystal

A

periodic arrangement atoms in total volume matter
made up from 1 single crystal

86
Q

Ex single crystal

A

quartz

87
Q

Polycrystal

A

same structure - diff orientation small single crystal

88
Q

Ex polycrystal

A

alpha phase titanium

89
Q

Crystal defects types

A

vacancy - misses lattice
interstitial - particle btw rows lattice
substitutional - substitution (ex: K+ for Na+ in KCl)
dislocation - NOT big enough for vacancy

90
Q

Effect crystal defects

A

determine:
electricity
strength
malleable
ductility

91
Q

Steel formation, effect

A

C in Fe
stronger
more brittle

92
Q

Movement atoms in crystal defects

A

Vacancy: diffusion (atom move -> create new vacancy)
Interstitial:
1. fast diffusion small size atoms (ex: C,N,B)
2. solid dissolution small size atoms (ex: C in Fe - steel)
Substitution: solid dissolution
(ex: Bronze - Sn solid dissolution in Cu)(bronZE -> use Sn)
(ex: Brass - Zn solid dissolution in Cu)(braSS -> use Zn)

93
Q

Types of linear defects, dislocations

A

edge
screw

94
Q

Edge

A

extra half plane thru solid structure

95
Q

Screw

A

1 side crystal displaces -> distortion
(screw up -> 1 side displaces)

96
Q

Effect of dislocate planes

A

weakens metal
reversible called hardening

97
Q

Effect of temp during melting

A

temp constant

98
Q

Effect when freezing/ solidification

A

high E liquid -> low E solid + heat

99
Q

What happens in super cooling phase

A

crystallization on pure metal

100
Q

When does crystallization complete

A

crystals form -> release latent heat fusion -> temp rise to freezing point -> constant -> complete

101
Q

Formation crystallization metals

A

nuclei -> crystallizes -> pure metal
pure metal dendrites shape (branch, elongated crystal)

102
Q

Types of homogeneous

A

pure metal
metal compound
solid solution (substitutional, interstitial)

103
Q

Types of heterogeneous

A

eutectic
eutectoid
(HEterogeneous -> eu -> eutectic, eutectoid)

104
Q

Effect pure metal

A

miscible in liquid
(mix)

105
Q

Solid solution (Formation alloy)

A

cooling mixed alloy -> atoms randomly distributed on unit cell lattice sites in each crystal grain

106
Q

Charac phase diagram

A

NO calc eq composition, structure depends on temp
MUST ID experimental

107
Q

Func phase diagram

A

structure alloy
microstructural predictions when alloy need heat treatment

108
Q

Ex eutectid alloy

A

Ag-Cu
(tectid -> Ah Cu -> Ag Cu)

109
Q

Charac eutectic system

A

binary alloy system
NO complete solubility in solid, liquid states
Effect:
-2 phases nucleate separate grains
-physically distinct
-diff mech prop

(eutectid - eu - 2 ->
binary alloy system
NO complete solubility -> 2 phases separate grain -> diff phys prop - diff mech prop)

110
Q

Ex dental eutectic system

A

porcelain - multiphase alloy: diff composition -> weaker

111
Q

Casting steps alloy

A
  1. prepare wax pattern
  2. embedding wax pattern (wax pattern in investment)
  3. prep mold (investment around wax pattern)
  4. burn wax pattern
  5. casting
  6. cooling, remove investment, sand blasting
  7. gross trimming
  8. electrogalvanic bath (remove sharp edges)
112
Q

Def lost wax casting process

A

mold burns at high temp -> reveal wax pattern

113
Q

Types alloy

A

non nobel
nobel

114
Q

Non nobel alloy

A

cobalt chromium
nickel chromium
Ti based alloy
(non nobel -> kids -> TiNiCo)

115
Q

Nobel alloy

A

gold containing alloy
palladium containing alloy
(nobel -> fancy -> gold, palladium)

116
Q

Classification nobel alloy gold content alloy

A

High gold content alloy
1. soft
2. medium
3. hard
4. extra hard
Medium gold content alloy
Low gold content alloy

(decrease -> increase -> high med low (soft med hard extra hard)

117
Q

Charac type 1 gold alloy

A

aka inlay gold
burnishable (burn - burnishable)

118
Q

Use type 1 gold alloy

A

small inlays - NO great stress
class3,5 restorations
easily

119
Q

Charac type 2 gold alloy

A

aka inlay gold

120
Q

Use type 2 gold alloy

A

inlay - moderate stress
onlay abutments (core of bridge)
full crowns
pontics (bridge connections)

121
Q

Use Type 3 gold alloy

A

inlay - high stress
fixed bridgework
denture bases
short span fixed partial denture
cast backing abutments(“bridge with metal root”)
pontics
full crown

122
Q

Charac type 3 gold alloy

A

age hardened

123
Q

Use Type 4 gold alloy

A

thin crowns - high stress
long span fixed partial denture
bars, clasps
fixed bridgework

124
Q

Charac type 4 gold alloy

A

age hardened by heat

125
Q

Use of medium, low gold content alloy

A

rarely for inlay
for full cast crowns

(med, low gold content alloy - cheaper than high -> can do a lot of it -> full cast crowns ; high gold content -> expansive - little work only -> inlay)

126
Q

Relationship decrease Au to hardness, proportional limit, strength, ductility, corrosion resistance

A

increase hardness
increase proportional limit
increase strength
decrease ductility
decrease corrosion resistance

(working-> low Au -> have to work -> higher hardness, strength, temper (prop limit) - no time for yoga -> decrease ductility, corrosion resistance (antioxidants)

127
Q

Types Palldium nobel alloy

A

Au-Pd-Ag
Au-Pd
Pd-Ag
Pd-Cu
Pd-Co

(Au, Pd ->
foundation: Au-Pd-Ag
1st 2: Au-Pd
2nd: Pd-Ag
3rd,4th, use Pd only -> Pd-Cu, Pd-Co)

128
Q

Charac, disad AuPdAg

A

corosion resistance
disad: color change to yellow
(yellow foundation-> corrosion resistance ; color change to yellow)

129
Q

Charac, dis PdAg

A

corrosion resistance
good porcelain bond strength
disad: porcelain color change to green b/d Ag diffusion to porcelain; gold agents reduce
(take last 2 of AuPdAg -> foundation -> 1. corrosion resistance, 2. porcelain bonding ; color change to green)

130
Q

Charac, dis AuPd

A

corrosion resistance
rigidity for partial dentures
good porcelain metal bonds
disad: high expansion porcelains -> thermal expansion incompatibility

(take 1st 2 of AuPdAg -> foundation -> 1. corrosion resistance, 2. porcelain metal bonds)
(1st 2 -> partially more responsibility -> rigid
-> partially -> partial dentures
-> deal with heat -> thermal expansion incompatibility w/ high expansion porcelains)

131
Q

Charac, dis PdCu

A

Cu cause probs in porcelain bonding but NOT in high Pd
high melting point compare to PdAg
use: large span fixed partial denture
(Cu
-> large span partial denture
-> better than PdAg -> higher melting point)

132
Q

Charac, dis PdCo

A

high coeff thermal expansion
limited use
disad: forms dark oxide
(Co -> handles lots heat -> high coeff thermal expansion)
(Co -> old -> forms dark oxide)

133
Q

Classification porcelain fused metal alloy

A
  1. Base
    a. NiCrBe
    b. NiCr
    c. CoCr
    d. Ti, Ti alloys
  2. Noble
    a. Pd - PdAg ; PdCu ; PdCo
    b. Au - AuPtPd ; AuPd ; AuPdAg

(base -> aka simple aka non nobel -> TiNiCo -> Ti: TiTi alloy ; Ni: NiCrBe, NiCr ; Co: CoCr)

134
Q

Ad porcelain fused metal alloy PFM

A

physical prop
chem prop
biocompatibility
workability
porc compatibility

135
Q

Types PFM

A

noble
precious
semiprecious
nonprecious

136
Q

Noble charac

A

resistance OXdation
NOT altered by acids

(noble -> rich -> access to antioxidant -> resistance OX, NOT altered by acid)

137
Q

Precious metal charac

A

expensive

138
Q

Precious alloy often used in dent

A

gold based alloy
silver palladium PdAg

139
Q

Non precious alloy often used in dent

A

Ti based
NiCr
CoCr
(non precious - non nobel - TiNiCo)

140
Q

Charac semiprecious

A

alloy contain silver, precious metal

141
Q

Charac non precious

A

non precious ingredient except for common inclusion 1-3% Be

142
Q

Physical prop choosing alloy contains

A

noble (corrosion resistance, inert)
hardness (occlusal wear resistance)
strength (load bearing)
elongation (imp in partial veneers crowns, abutment)
fusion temp
melting range
sag resistance (amount distortion at high temp)
thermal expansion (O residual stress)
bond strength
composition alloy (porc discoloration)

(budget -> comp alloy ; noble -> phys prop: hardness, strength -> bond strength -> elongation -> chem prop: fusion temp, melting range, thermal expansion, sag resistnce)

143
Q

Alloys for removable denture

A

non nobel
Ti
NiCr
CoCr
CoCrNi
(removable -> unimportant -> non nobel -> have CoCrNi)

144
Q

extra composition NiCr

A

Ni
Cr
Al
Be

145
Q

Charac Ni

A

cause allergy

146
Q

Charac NiCr

A

Ni3Al: intermetallic compound
increase strength

147
Q

Charac Cr alloy

A

Cl attacks -> NO use for cleaning appliances made from Cr alloy
brittle
ZrO2 thin layer -> decrease Cr release level

(Cr -> Cl attacks -> ZrO2)

148
Q

Charac Ni in CoCrNi

A

increase elongation
(Ni -> mimi -> fat, allergic to her-> elongation , allergy)

149
Q

Charac Ti

A

diff manipulation
high casting temp
rapid OXdation
melting done best in Ar atmosphere

(Ti -> diff manipulation -> hot tempered aka high casting temp -> wrinkles -> rapid OXdation -> cooling down aka melting best in Ar atmosphere)

150
Q

Alloys for fixed partial denture

A

non nobel
(normal TiNiCo)
Titanium
NiCr
CoCr

151
Q

diff btw composition NiCr removable, fixed denture

A

removable: have Al, Be
fixed: Be

152
Q

Charac NiCr fixed denture

A

etched electrochemically
better porc bonding than Be free NiCr

153
Q

Charac Ti fixed denture

A

alternative to gold for inlay, onlay
non nobel, not precious
high biocompatibility
low cost
low density
corrosion resistance
room temp lattice: hexagon closed packs (alpha)
high temp lattice: body centered cubic (beta) - stronger, < ductile (high temp aka hot aka hot body -> body-beta -> stronger, less ductile)

(Ti -> non nobel -> low cost -> low density -> alt gold inlay onlay -> high biocompatibility -> high corrosion resistance)

154
Q

Charac NiCr, CoCr fixed denture

A

sensitive to routine lab
cast NOT accurate comparing type3,4 gold, low gold alloys

155
Q

Why non nobel for fixed dentur

A

high strength
high hardness
high stiffness
low cost

156
Q

Effect elements released in mouth during corrosion

A

toxicity
allergy
carcinogenesis

157
Q

Potent allergens

A

Ni
Co

158
Q

Carcinogen element

A

Be
(be -> little -> carcinogen -> Be carcinogen)

159
Q

Surgical alloy

A

Cr
a. CoCr
a. NiCoCr

160
Q

Classification physical prop

A
  1. Mech prop
    a. Strength (tensile, compressive, shear)
    b. Hardness (Birnell, Vickers, Knoop, Rockwell, Shore A)
    c. Elastic (elastic modulus, resilience)
    d. Plasticity (ductility, percent elongation, yield strength)
  2. Electrical, electrochem prop
    a. Electrod potential
    b. Electrical resistivity
  3. Thermal prop
    a. Thermal expansion
    b. Heat flow (Thermal conductivity, diffusivity)
161
Q

Vicks harness

A

diamond pyramid
square indent
are square indent depends on force, resistance material, angle

162
Q

Func Vicks hardness

A

resistance of material

163
Q

Shore hardness

A

A: truncated cone shape
B: cone shape

164
Q

Func shore hardness

A

ID hardness rubber, polymer

165
Q

Birnell

A

stainless steel ball

166
Q

Knoop

A

diamond pyramid
1 diagonal longer
(K -> 1 long line, 1 short -> pyramid w/ diagonal longer)

167
Q

formula compressive stress

A

stress= F/A

168
Q

3 point tensile strength/ Flexural strength - measure compression force

A

specimen into machine 2 support points
measured during applied compression force vertically

169
Q

meausure tensile strength

A

dog bone shape
measure tensil

170
Q

Diametral tensile strength

A

cylindrical specimen
diametral position
cross sectional tensile force vertically to applied compression

171
Q

ID poly shrinkage based on

A

Archimedes principle
volume changes btw poly, unpoly based on density determination

172
Q

Fracture toughness Kic def

A

E to break surface intergrity
regarding fragile material (Ceramic)

173
Q

Measure fractur toughness by

A

3 point flexural w/ rectangular specimen -> applied force -> cracking -> Kic calc -> ID applied fprce, para specimen, notch

174
Q

Shear bond strength measure

A

sample attach to base surface
compression force vertical to adhesive layer surface

175
Q

Use micro tensile bond strength

A

composite
dentin bod strength measurement

176
Q

micro tensile bond strength

A

cavity prep -> filling material placed -> tooth filling sliced in microtome 2 directions -> test tensile

177
Q

What does viscosity measures

A

resistance- gradual deform
by shear, tensile stress

178
Q

Newton viscosity cond

A

parallel
steady flow

179
Q

Newtonian fluid

A

shear stress proportional to shear rate
viscosity constant, independent shear rate

180
Q

Pseudoplastic

A

flow index < unity
-> increase shear rate
-> non proportional increase shear stress
-> decrease viscosity (thining)

181
Q

Dilatant

A

flow index > unity
-> increase shear rate
-> proportional increase shear stress
-> increase viscosity (thickening)

182
Q

Thixotropy

A

time dependent shear thining (pseudoplasticity)
thick (viscous) gel, fluid -> shaken -> thin (less viscous) -> fixed time -> return viscous

183
Q

Ex thixotropy

A

polyether impression material

184
Q

Aim casting

A

produce metallic respiration

185
Q

Cond to correspont investment material at application casting

A

investment material compensate thermal volume changes of wax pattern, used alloy

186
Q

elasticity lowest - highest ceramic metal polymer

A

polymer -> metal -> ceramic
(elasticity PMC)

187
Q

Length plastic deform lowest - highest ceramic metal polymer

A

ceramic - metal - polymer

188
Q

Charac cross linked polymer

A

strong covalent bond -> strong bonded unit

189
Q

Free radical add. poly accelerated by

A

heat
light
small amount peroxides

190
Q

use of soft, med, hard, very hard Au content precious alloy

A

soft: 80-90% small inlay
med: 71-79% inlays
hard: 62-70% fixed prosthetics (if Cu min 11%)
very hard: 50-61% long span bridges, partial dentures (if Cu min 11%)

191
Q

Ad precious alloy in dent

A

biocompatibility
good casting into molds
ductile (deform NO cracking)
easy polish

192
Q

Formation/ Hardening process precious alloy

A

homogenization 700celcius
harden 400celcius 30min
cool down

193
Q

Homogen

A

entire specimen in 1 phase
same physical, chem prop

194
Q

Heterogen

A

2/more phase in specime

195
Q

Why make alloy

A

better material prop
better financially
better processing in lab

196
Q

Intermetallic compound

A

material all comp are metals

197
Q

Charac intermetallic compound

A

brittle
break into pieces > alloy

198
Q

Special types precious

A

-white gold
-very low gold content alloys divided into med, low

+med of very low gold content alloy: 40-60% gold - rest: metals (Ag, Pd)
+low of very low gold content alloy: 15-20%

199
Q

Use, charac of med of very low gold content special precious alloy

A

subs hard, very hard
low ductility
use:
retainers (orthodontics)
partial denture

(almost last on list -> sometimes bad sometimes good
-> flexible -> ductility
-> at teenage age/ old -> need retainers/ partial denture -> use: retainers, partial denture)

200
Q

Charac of low of very low gold content special precious alloy

A

worst mech prop
NO homogeneous
high melting point
subs hard

(last on the list -> worst b/c unlike others, hot tempered
-> worst mech prop
-> NO homo
-> high melting point)

201
Q

White gold def, charac

A

Ag+Pd - NO gold
high strength
high melting point
expensive
use: inlays, crowns, bridges

202
Q

More ex non precious

A

steel
brass
CoCr - 55-65%Co ; <30% Cr

203
Q

Charac, use CoCr (same for NiCr)

A

easy to cast
high melting point
hard, strong
acid resistant
low density
use: bridges, crowns

(Co - not heavy, resistance to acid
-> low density, acid resistant
-> can carry over bridges -> become crown -> use: bridges, crowns)

Dental material (7 decks)

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