Dentine bonding

Question 1

structure of dentine

Answer 1

70% hydroxyapitie
20% organic material
10% water

Question 2

dentine has more of a .. composition

Answer 2

heterogeneous

more difficult substrate to bond to an adhesive

Question 3

whats found in dentine

Answer 3

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

Question 4

what is a condiitoner

Answer 4

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

Question 5

what is coupling agent/primer

Answer 5

intermeidiary substance able to bond to a substrate and adhseive

Question 6

what is a sealer

Answer 6

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

Question 7

what does the dentine conditioner do

Answer 7

modify the smear layer

dissolves the hydroxyapatite and opening tubules

Question 8

what is the smear layer

Answer 8

mixture of proteins, hydroxyapatite

Question 9

what acids are usually used

Answer 9

EDTA
maleic acid
oxalic acid
phosphoric acid
nitric acid

Question 10

is dentine hydrophobic or philic

Answer 10

hydrophilic

resin is hydrophobic

Question 11

what can dentine bond to

Answer 11

as it is hydrophilic

• hydroxyl groups
• carboxyl groups
• phosphate groups

Question 12

what can you now also bond hydrophobic resins to

Answer 12

methacrylate groups

- use a spacer to stick them together

Question 13

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

Answer 13

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

Question 14

what is a coupling agent and what does it do

Answer 14

bifunctional monomer

combines 3 parts

Question 15

what parts does a coupling agent bind

Answer 15

polar group
spacer
methacrylate group

Question 16

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

Answer 16

affinity for the dentine

Question 17

what does the spacer do in the bond

Answer 17

allows the two parts to attach

Question 18

what does the metharcylate group do in the mond

Answer 18

produces the polymerisation

Question 19

examples of a bifunctional monomer

Answer 19

HEMA
MEP-P
NPG-GMA

Question 20

what are bifunctional monomers and what are they composed of

Answer 20

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

Question 21

what is needed to carry monomer into the collagen

Answer 21

solvent or water

Question 22

what does the dentine look like after priming

Answer 22

surface of hydrophobic methacrylate groups

Question 23

what does the surface of hydrophobic methacrylate groups allow

Answer 23

direct bond to the surface with methacrylate based resin

Question 24

what are methacrylate based resin examples

Answer 24

Bis-GMA
UDMA
light or chemical cure

Question 25

stages for dentine bonding

Answer 25

apply conditioner apply primer apply sealer

Question 26

what does conditioner do

Answer 26

removes smear layer and opens tubules

Question 27

what does primer do

Answer 27

bonds to the hydrophilic collagen and hydroxyapitie | leaves the methacrylate free on the other side

Question 28

what does sealer do

Answer 28

seals tubules and bonds to the primer

Question 29

concerns with dentine bonding

Answer 29

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

Question 30

what is the issue of surface energy with enamel and dentine

Answer 30

less spreading of adhesives in dentine due to the lower SE

Question 31

what is smear layer

Answer 31

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

Question 32

enamel crystals are

Answer 32

solid crystals and non dynamic | dentine is permeable and dynamic

Question 33

How does polymer shrinkage occur

Answer 33

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

Question 34

issues with polymerisation shrinkage

Answer 34

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

Question 35

how to reduce polymerisation shrinkage effects

Answer 35

- filler particles - new monomer systems - curing in small intervals

Question 36

what happens if you dry dentine too mcuh

Answer 36

collagen collapses | - formation of a dense layer that the primer cannot penetrate

Question 37

what does the solvent do and what does it carry

Answer 37

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

Question 38

wet dentine

Answer 38

porous collagen - primer can penetrate and produce molecular entanglement - good bond strenght

Question 39

dry dentine

Answer 39

- dense collagen - primer cannot penetrate and cannot produce molecular entanglement - weak bond strenght

Question 40

Type 1 bonding agents

Answer 40

3 stage systems - etch - prime - seal

Question 41

give some examples to type 1 bonding agents/brands

Answer 41

allbond optibond scotch bond MP

Question 42

type 2 bonding agetns

Answer 42

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

Question 43

commercial examples of type 2

Answer 43

one step optibond solo scotch bond 1

Question 44

type 3 bonding agents

Answer 44

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

Question 45

commertial example of type 3

Answer 45

clearfil SE bond

Question 46

type 4 bonding agent

Answer 46

condition prime and seal simplest - weakest bond

Question 47

which type of bonding agent is the hardest to use

Answer 47

type 1 | - requries excellent technique

Question 48

type 2 vs 1

Answer 48

almost equallly difficult | bond strength is generally worse