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Basic dental care yr 2 > Dentine bonding > Flashcards

Dentine bonding Flashcards

1
Q

structure of dentine

A

70% hydroxyapitie
20% organic material
10% water

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2
Q

dentine has more of a .. composition

A

heterogeneous

more difficult substrate to bond to an adhesive

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3
Q

whats found in dentine

A

dentinal tubules
extend from the external surface to the pulp
transmit pain to the pulp when dentine is exposed

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4
Q

what is a condiitoner

A

substance that modifies the characteristics of a substance so a bond can be created e.g. acid etch

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5
Q

what is coupling agent/primer

A

intermeidiary substance able to bond to a substrate and adhseive

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6
Q

what is a sealer

A

substance that flows into dentinal tubules creating a methacrylate based layer
- ensures adhesion

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7
Q

what does the dentine conditioner do

A

modify the smear layer

dissolves the hydroxyapatite and opening tubules

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8
Q

what is the smear layer

A

mixture of proteins, hydroxyapatite

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9
Q

what acids are usually used

A 
EDTA
maleic acid
oxalic acid
phosphoric acid
nitric acid
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10
Q

is dentine hydrophobic or philic

A

hydrophilic

resin is hydrophobic

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11
Q

what can dentine bond to

A

as it is hydrophilic

  • hydroxyl groups
  • carboxyl groups
  • phosphate groups
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12
Q

what can you now also bond hydrophobic resins to

A

methacrylate groups

- use a spacer to stick them together

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13
Q

what is a spacer used for when bonding resin to methacrylate groups

A

long enough to prevent rigidity and allow both ends to bond freely/move around

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14
Q

what is a coupling agent and what does it do

A

bifunctional monomer

combines 3 parts

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15
Q

what parts does a coupling agent bind

A

polar group
spacer
methacrylate group

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16
Q

what does the polar group do in the bond of the spacer

A

affinity for the dentine

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17
Q

what does the spacer do in the bond

A

allows the two parts to attach

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18
Q

what does the metharcylate group do in the mond

A

produces the polymerisation

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19
Q

examples of a bifunctional monomer

A

HEMA
MEP-P
NPG-GMA

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20
Q

what are bifunctional monomers and what are they composed of

A 
dentine primers/coupling agents
made of
- polar group
-space
-metharylate/acrylate/functional group
21
Q

what is needed to carry monomer into the collagen

A

solvent or water

22
Q

what does the dentine look like after priming

A

surface of hydrophobic methacrylate groups

23
Q

what does the surface of hydrophobic methacrylate groups allow

A

direct bond to the surface with methacrylate based resin

24
Q

what are methacrylate based resin examples

A

Bis-GMA
UDMA
light or chemical cure

25
Q

stages for dentine bonding

A

apply conditioner
apply primer
apply sealer

26
Q

what does conditioner do

A

removes smear layer and opens tubules

27
Q

what does primer do

A

bonds to the hydrophilic collagen and hydroxyapitie

leaves the methacrylate free on the other side

28
Q

what does sealer do

A

seals tubules and bonds to the primer

29
Q

concerns with dentine bonding

A

not as durable as enamel bonding

  • complex/heterogenous substrate
  • dentine is permeable and dynanic
  • lower surface energy than enamel
  • formulation of smear layer
  • hydrophilic dentine/hydrophobic resins
  • problems associated to wetting
  • problems with polymer shrinkage
30
Q

what is the issue of surface energy with enamel and dentine

A

less spreading of adhesives in dentine due to the lower SE

31
Q

what is smear layer

A

coagulated protein/HA layer which includes accumulation of debris formed on the dentine during instrumentation

32
Q

enamel crystals are

A

solid crystals and non dynamic

dentine is permeable and dynamic

33
Q

How does polymer shrinkage occur

A

monomer molecules are converted into polymer network
exchanging van der walls forces in covalent bond spaces
- creates contraction stresses

34
Q

issues with polymerisation shrinkage

A

creates contraction stresses

  • shrinkage can result in bond failure and poor marginal adaptation
  • gap formation between the cavity and restorative material may lead to bacterial penetration and plural damage
  • sensitivity/pain , recurrent caries, bacteria
35
Q

how to reduce polymerisation shrinkage effects

A
  • filler particles
  • new monomer systems
  • curing in small intervals
36
Q

what happens if you dry dentine too mcuh

A

collagen collapses

- formation of a dense layer that the primer cannot penetrate

37
Q

what does the solvent do and what does it carry

A

carries the primer

- displaces the water out of collagen and brings in the bifunctional monomer allowing good penetration

38
Q

wet dentine

A

porous collagen

  • primer can penetrate and produce molecular entanglement
  • good bond strenght
39
Q

dry dentine

A
  • dense collagen
  • primer cannot penetrate and cannot produce molecular entanglement
  • weak bond strenght
40
Q

Type 1 bonding agents

A

3 stage systems

  • etch
  • prime
  • seal
41
Q

give some examples to type 1 bonding agents/brands

A

allbond
optibond
scotch bond MP

42
Q

type 2 bonding agetns

A

combined 2 final steps
1- etch then rinse
2- prime and seal

43
Q

commercial examples of type 2

A

one step
optibond solo
scotch bond 1

44
Q

type 3 bonding agents

A

self etching primers

combines 1st 2 stages of the 3 stage (acidic monomers that etch and prime)

45
Q

commertial example of type 3

A

clearfil SE bond

46
Q

type 4 bonding agent

A

condition prime and seal
simplest
- weakest bond

47
Q

which type of bonding agent is the hardest to use

A

type 1

- requries excellent technique

48
Q

type 2 vs 1

A

almost equallly difficult

bond strength is generally worse

Basic dental care yr 2 (36 decks)

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