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DMS luting agents > dental luting agents > Flashcards

dental luting agents Flashcards

1
Q

what are they used for?

A

to cement indirect restorations

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2
Q

properties of a luting agent

A 
radiopaque
viscosity and film thickness
ease of use
mechanical properties
biocompatible
cariostatic
solubility
aesthetics
marginal seal
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3
Q

what does the viscosity depend on?

A

size of powder or filler particles

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4
Q

viscosity requirements

A

must be low - 20um or less

to allow seating of restoration without interference

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5
Q

how does viscosity change as agent sets?

A

increases

- so must seat Rx quickly and maintain pressure

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6
Q

film thickness requirements

A

as thin as possible

ideally 25um or less

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7
Q

how are many made easy to use?

A

encapsulated

clicker system

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8
Q

what should the working time be long enough to allow for?

A

seating

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9
Q

why is it preferable for agents to be radiopaque?

A

makes it easier to see marginal breakdown or secondary caries

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10
Q

ideal marginal seal

A

ideally chemical bond to tooth and indirect restoration

- permanent and impenetrable

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11
Q

ideal aesthetics

A

tooth coloured - variation in shade and translucency

non-staining - problem with some of the resin materials

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12
Q

ideal solubility

A

low

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13
Q

biocompatibility

A

not toxic
not damaging to pulp (pH, heat on setting)
low thermal conductivity
- as many Rxs metal - want the cement to be insulating

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14
Q

cariostatic

A 
F releasing (GI) - bacteria don't like high F
antibacterial
important in preventing secondary caries around crown margins
some redox reaction materials bactericidal - but tend to be bad for pulp
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15
Q

ideal mechanical properties

A

high compressive strength
high tensile strength
high hardness value
YM similar to tooth

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16
Q

types of materials

A 
dental cement
 - zinc phosphate
 - zinc polycarboxylate
GI cement
 - conventional
 - resin-modified
composite resin luting agents
 - total etch for use with DBA
 - self-etch
 - requires etch but has own bonding agent incorporated
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17
Q

zinc phosphate 2 basic components

A

powder

liquid

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18
Q

zinc phosphate powder

A 
ZnO >90%
 - main reactive ingredient
MgO2 <10%
 - white colour
 - increases compressive strength
other oxides (alumina and silica)
 - improve physical properties
 - alter shade of set material
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19
Q

zinc phosphate liquid

A

H3PO4 (aq) 50%

oxides which buffer - Al2O3, ZnO

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20
Q

zinc phosphate advantages

A

easy to use

cheap

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21
Q

zinc phosphate liquid - oxides which buffer - Al2O3

A

ensures even consistency of set material

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22
Q

zinc phosphate liquid - oxides which buffer - ZnO

A

slows reaction, better working time

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23
Q

zinc phosphate reactions

A

initial - acid base
then hydration reaction
formation of crystallised phosphate matrix (around unreacted ZnO particles)
Al2O3 prevents crystallisation - amorphous glassy matrix of the zinc phosphate salt surrounding unreacted ZnO powder
matrix almost insoluble, but porous and contains free water from the setting reaction
cement subsequently matures (larger hydration reaction) binding this water - stronger, less porous material

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24
Q

zinc phosphate problems

A 
low initial pH2
exothermic setting reaction
not adhesive to tooth or restoration
not cariostatic
final set takes 24hrs
brittle 
opaque
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25
Q

zinc phosphate problems - low initial pH

A

can cause pulpal irritation as pH can take 24hrs to return to normal

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26
Q

zinc phosphate problems - not adhesive to tooth or restoration

A

works like grout on tiles just filling in any spaces
retention may be slightly micro mechanical due to surface irregularities on prep and restoration
advantage for temporary cement
- can use cavitron to remove instead of drill
- good for poorly retentive temps - quite rigid

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27
Q

zinc polycarboxylate cement chemistry

A

phosphoric acid replaced by poly acrylic acid

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28
Q

zinc polycarboxylate cement advantages

A

bonds to tooth in similar way to GIC (not as good)
less heat of reaction
pH low to begin with but returns to neutral more quickly and longer chain acids don’t penetrate dentine as easily
cheap

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29
Q

zinc polycarboxylate cement disadvantages

A

difficult to mix and manipulate
soluble in oral env at lower pH
opaque
lower modulus and compressive strength than zinc phosphate

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30
Q

why are the dental cements mainly historic?

A

all of the more modern materials utilise chemical bonding to the tooth surface (some also bond to indirect restoration)

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31
Q

what is the main difference between GI filling material and cement?

A

particle size of glass

<20um to allow for a suitable film thickness

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32
Q

AquaCem

A

GIC

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33
Q

GIC reaction chemistry

A

acid base reaction between glass and polyacid

dissolution, gelation, hardening

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34
Q

GIC bonding

A

cement bonds to tooth
- ion exchange with Ca in E and D
- H-bonding with collagen in the dentine
=fairly strong durable and possibly dynamic bond to tooth

no chemical bond to restoration surface
- sandblast to allow mechanical adhesion

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35
Q

advantages of GIC

A 
easy to use
durable
low shrinkage
long term stability
relatively insoluble once fully set (Al)
 - first week a bit soluble
aesthetically better than zinc phosphate
self-adhesive to tooth substance
fluoride release
cheap
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36
Q

RMGIC difference with filling material

A

glass particle size smaller so it has an acceptable film thickness

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37
Q

RMGIC chemistry

A

cGIC liquid and powder but liquid also contains a hydrophilic monomer
- HEMA (hydroxyethylmethacrylate)

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38
Q

in RMGIC why does the monomer need to be hydrophilic?

A

GIC is a water-based material so it needs to be water-soluble

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39
Q

RMGIC reactions

A

same acid base reaction as cGIC
- continues for some time
light activation - polymerisation of the HEMA and any co-polymers in the material - rapid initial set
GI setting within resin matrix

some materials have a secondary cure via a redox reaction - allows ‘dark curing’ - where material not exposed to light will cure

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40
Q

RMGIC advantages of having resin

A 
shorter setting time
longer working time
higher compressive and tensile strengths
higher bond strength to tooth
decreased solubility
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41
Q

RMGIC problems

A

HEMA cytotoxic - v important that no monomer remains as it can damage the pulp
HEMA swells over time - expands in a wet env
- can’t use to cement conventional porcelain crowns as they may crack
- don’t use to cement posts - may split root
no bond to indirect restoration

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42
Q

how do composite luting agents vary form the filling material?

A

viscosity and filler particle size

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43
Q

what do composite luting agents need to be used with and why?

A

DBA

no bond to tooth without

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44
Q

what can a light cure composite luting agent be used for?

A

veneers

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45
Q

advantages of composite luting agents

A

better physical properties
lower solubility
better aesthetics

46
Q

disadvantages of composite luting agents

A

technique sensitive - need dry env

physical properties reduced by 25% if not light cured

47
Q

bonding to indirect composite

A

composite bonds to composite
- both hydrophobic so don’t need anything between
bond strength lower to inlay fitting surface than to new composite
bond micro mechanical to rough internal surface of inlay
chemical to remaining C=C bonds on fitting surface of the inlay

48
Q

what should be used to cement indirect composites?

A

dual cure composite resin cement and DBA

- light penetration through an inlay poor

49
Q

bonding to indirect composite diagram

A

resin inlay - hydrophobic
composite luting resin - hydrophobic
DBA - make tooth surface hydrophobic
tooth - hydrophilic

50
Q

why does porcelain need to be bonded to the tooth?

A

it is brittle so needs to be bonded to tooth to prevent fracture (relying on tooth for strength)

51
Q

etching the surface of porcelain

A

HF acid (v toxic)

52
Q

why does the porcelain surface need to be etched?

A

untreated porcelain smooth and non-retentive

etch to make rough retentive surface

53
Q

why does porcelain require a surface wetting agent?

A

as it is not hydrophobic and compatible with composite resin luting agents

54
Q

what is silane coupling agent applied to?

A

etched porcelain surface, ideally as a monolayer

55
Q

what does the silane coupling agent bond to?

A

oxide groups on porcelain

resin groups in composite resin luting agent

56
Q

how does a silane coupling agent work?

A

in the same way as DBA to tooth
hydrophobic end - resin groups
hydrophilic end - to oxide on porcelain

57
Q

components of bonding to porcelain

A 
tooth - hydrophillic
DBA - makes tooth surface hydrophobic
composite luting resin - hydrophobic
silane - makes it hydrophillic
porcelain - hydrophilic
58
Q

when is the only time you should use light cured?

A

if porcelain thin and use increased curing time

if thick use dual cured

59
Q

what should you do with composite luting resin before curing?

A

remove as much excess as possible

60
Q

composite cements staining

A

long-term dual curing materials stain more whereas light-cured won’t

61
Q

do metals bond directly to composite?

A

no

62
Q

what should be done to the metal surface before cementing?

A

sandblasting
roughens surface but doesn’t give undercut surface of etching
- need chemical bonding to strengthen bond

63
Q

etching metals - electrolytic etching

A

metal in acid, pass electric current through it
removes the different phases of the alloy at different rates
gives v retentive surface
BUT
- technique sensitive
- beryllium containing alloys work best - carcinogenic to lab worker
- cant etch precious metals at all
rarely used

64
Q

bonding to non-precious metal components

A 
tooth - hydrophillic
DBA - makes surface hydrophobic
composite luting resin - hydrophobic
metal bond agent - makes it hydrophilic
non-precious metal - hydrophilic
65
Q

metal bonding agent

A

materials with carboxylic and phosphoric acid derived resin monomers
MDP and 4-META
have acidic end - reacts with the metal oxide and makes the surface hydrophobic
has C=C end

66
Q

what luting agent should be used for bonding to non-precious metal?

A

dual cure as light won’t penetrate metal

67
Q

bonding to precious metal

A

change precious alloy composition to allow oxide formation
- increase copper content and heat 400 degrees in air

tin plate

sulphur based chemistry of bonding agent

all complicated and technique sensitive

68
Q

self-adhesive composite resin

A 
metal coupling agent incorporated into the composite resin
simplifies bonding process
MDP used in panavia
consistent results
good film thickness
opaque
moisture sensitive
expensive
69
Q

Panavia

A

anaerobic self-curing composite resin which contains MDP
anaerobic - will only set with no air
- put special gel on - to ensure the edges are all set

70
Q

bonding to non-precious metal with panavia ex components

A

tooth
(own) DBA
panavia ex
non-precious metal

71
Q

RelyX Unicem

A

self-etching composite resin luting agent

72
Q

self-etching composite resin luting agents

A

combination of a composite resin cement and a self-etching DBA
has self-etching and self-bonding
has MDP - will stick to oxide groups to metal and porcelain

73
Q

chemistry of self-etching composite resin luting agents

A

attaches like a self-etching primer (sort of)
acid groups in the resin bind to Ca of HA in tooth
- bind stabilising attachment
ions from dissolution of filler neutralise remaining acidic groups - chelate reinforced methacrylate network
has acid groups attached to long chain polymers, act on E and D surface so more chemical can attach in that area

74
Q

self-etching composite resin luting agents problems

A

requires good moisture control
? bond strength to enamel due to inadequate etching
pH of carboxylic monomer doesn’t stay low for long enough to give a good etch
limited removal of smear layer/significant infiltration into tooth surface (only a couple of microns)
v expensive

75
Q

self-etching composite resin luting agents advantages

A

good bond strength to dentine
micro mechanical adhesion
mechanical strength and wear resistance slightly lower than conventional resin luting agents but better than ‘cements’
easy to use

76
Q

self-adhesive composite resin

A 
metal coupling agent incorporated into the composite resin
simplifies bonding process
MDP used in panavia
consistent results
good film thickness
opaque
moisture sensitive
expensive
77
Q

Panavia

A

anaerobic self-curing composite resin which contains MDP
anaerobic - will only set with no air
- put special gel on - to ensure the edges are all set

78
Q

bonding to non-precious metal with panavia ex components

A

tooth
(own) DBA
panavia ex
non-precious metal

79
Q

RelyX Unicem

A

self-etching composite resin luting agent

80
Q

self-etching composite resin luting agents

A

combination of a composite resin cement and a self-etching DBA
has self-etching and self-bonding
has MDP - will stick to oxide groups to metal and porcelain

81
Q

chemistry of self-etching composite resin luting agents

A

attaches like a self-etching primer (sort of)
acid groups in the resin bind to Ca of HA in tooth
- bind stabilising attachment
ions from dissolution of filler neutralise remaining acidic groups - chelate reinforced methacrylate network
has acid groups attached to long chain polymers, act on E and D surface so more chemical can attach in that area

82
Q

self-etching composite resin luting agents problems

A

requires good moisture control
? bond strength to enamel due to inadequate etching
pH of carboxylic monomer doesn’t stay low for long enough to give a good etch
limited removal of smear layer/significant infiltration into tooth surface (only a couple of microns)

83
Q

self-etching composite resin luting agents advantages

A

good bond strength to dentine
micro mechanical adhesion
mechanical strength and wear resistance slightly lower than conventional resin luting agents but better than ‘cements’

84
Q

self-etching composite resin luting agents bonding to E

A

lower strength than to dentine (less acid)

etch with phosphoric acid

85
Q

self-etching composite resin luting agents bonding to D

A

better than to enamel

don’t need to etch

86
Q

self-etching composite resin luting agents bonding to ceramics

A

brand specific

RelyXUnicem seem to bond quite well to sandblasted Zi

87
Q

self-etching composite resin luting agents bonding to metal

A

better to non-precious

not good enough to cement ortho brackets

88
Q

self-etching composite resin luting agents research

A

v few clinical studies - nothing long term enough

89
Q

self-etching composite resin luting agents vs traditional uses

A

if you can’t use a DBA and conventional resin cement you cant use these

90
Q

self-etching composite resin luting agents components

A

tooth
self-etching composite resin luting agent
indirect Rx

91
Q

MCC

A

GIC

92
Q

metal post

A

GIC

93
Q

fibre post

A

dual cure composite and DBA

94
Q

veneer

A

light cure composite and DBA

95
Q

adhesive bridge

A

anaerobic cure composite

96
Q

Zi crown

A

GIC

97
Q

composite inlay

A

dual cure composite and DBA

98
Q

carnauba wax

A

weakens structure of set cement - easier to remove

99
Q

gold restoration

A

GIC

100
Q

general rules of what to use

A

if you can break it with your fingers use a resin cement
if you can throw it off a wall you can stick it in with a cement
exception adhesive bridge

101
Q

cementing temporary restorations requirements

A

soft for easy removal
prep needs to be physically retentive
can be used for trial lute of permanent

102
Q

what won’t temporary cements work with?

A

veneer or round onlay - not retentive

103
Q

temporary cements 2 paste systems

A

base and catalyst/accelerator

104
Q

temporary cements 2 paste systems - base

A

ZnO, starch and mineral oil

105
Q

temporary cements 2 paste systems - accelerator

A

resins, eugenol or ortho-EBA and carnauba wax

106
Q

carnauba wax

A

weakens structure of set cement - easier to remove

107
Q

how can you make temp cement weaker?

A

incorporate petroleum jelly into the mixture

108
Q

2 main types of temporary cement

A

with eugenol

without eugenol

109
Q

when shouldn’t you use temp cements containing eugenol?

A

where permanent will be cemented with a resin cement

eugenol plasticiser for composite - any residual eugenol may interfere with the setting

110
Q

why should you ensure complete removal of the temporary cement?

A

may stop you seating restoration

will stop you bonding to tooth surface

DMS luting agents (1 decks)

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