Principles of Adhesion, Acid Etch and Dentine Bonding Agents including self etch Flashcards Preview

Applied Dental materials > Principles of Adhesion, Acid Etch and Dentine Bonding Agents including self etch > Flashcards

Flashcards in Principles of Adhesion, Acid Etch and Dentine Bonding Agents including self etch Deck (29)
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1

what does adhesive materials offer potential to?

-Seal vulnerable pits and fissures
-Conserve tooth tissue
-Reduce/eliminate microleakage

2

what are the 3 approaches to achieving adhesion?

-Micromechanical attachments
E.g. acid etch and application of resins

-Chemical adhesion to enamel/dentine
E.g. coupling agents/cements containing polyacids (not considered further in this lecture)

-Complex – involving wetting, penetration and formation of bound material of restorative substrate interface
E.g. modern dentine bonding agents

3

what helps achieving adhesion?

if the agents concerned demonstrate wetting (contact angle)
- lower the angle, the better wetting

4

why does good wetting help adhesion?

Attraction between adhesive and adherend lowers surface tension of adhesive so will flow into irregularities

5

what is the purpose of acid etch? (enamel)

Increases surface roughness microscopically

Increases enamel surface energy:
-removes surface contaminants
-increases wetting
-facilitates micromechanical retention

6

what factors affect adhesion?

-Etching time
-Washing
-Drying

7

Describe how etching time affects.

-Enough for effect
-Not to long as allows re precipitation of Calcium and Phosphate
-Typically 10-60 seconds

8

Describe how washing affects.

Approx 60s to remove debris

9

Describe how drying affects.

To enable hydrophobic resin to penetrate and attach

10

With adhesion to dentine , why is it important to stick to same manufacturer?

-to avoid potential chemical compatibility problems (composite and DBA)

-to avoid light curing problems especially if using LED (composite, DBA and curing unit)

11

What are the properties of an ideal dental adhesive?

- a high bond strength to enamel & dentine
-an immediate and durable bond
-a reliable bond
-prevent bacterial ingress
-be safe to use
-be simple to use

12

What are properties of dentine?

-hydrophilic (adhesives are hydrophobic)
-a vital tissue
-consists of inorganic & organic material
-is covered by a smear layer

13

What are problems with dentine bonding?

-Cavity preparation results in a smear layer that occludes tubules
- Dentinal tubules following removal of smear layer but no air drying

14

what is the manufacturer term for primer?

dentine conditioner

15

what is the manufacturer term for coupling agents?

Primers

16

what is the manufacturer name for sealer?

sealers

17

Describe primers.

-acids
-alter surface appearance and characteristics of dentine

18

Describe coupling agents.

components that do the sticking

19

Describe sealer.

-flows into dentinal tubules
-seals dentine with surface layer rich in methacrylates
-ensures bonding to the resin in the composite

20

Give example of dentine conditioners and describe how they work.

-Eg. Maleic, oxalic, phosphoric, nitric acids
-Acid base reaction with hydroxyapatite
-open dentinal tubules
-demineralize surface dentine to a depth of 4 microns

21

Describe how coupling agents (primers) work.

-Act as adhesives
-Bond hydrophobic composites to hydrophilic dentine
-General formula M-R-X dissolved in volatile solvent

22

what is the most popular coupling agent (primer)?

HEMA

23

Describe the effects of HEMA.

-Dermatological effects and rubber gloves
-Bonds to hydroxyl of the apatite and amino groups of the collagen
-Solvent (e.g. ethanol/acetone) enhances penetration by seeking and displacing water carrying the coupling agent with it

24

Describe sealers.

-Resins
-mix of BIS-GMA & HEMA

25

Discuss the time depended degeneration.

-Acid opening of tubules risks nano leakage
-Dentine etch greater than resin can penetrate
-Dentine microstructure disruption and failure

26

what are the main 3 stages?

1. Application of etchant, washed off creating demineralised dentine layer
2. Application of the primer
3. Application of the sealer

27

what are the two stages of approach one?

1. Application of etchant, washed off creating demineralised dentine layer
2. Application of the primer and sealer in single solution

28

what are the two stages of approach two?

1. Application of self etching primer
2. Application of the sealer in single solution

29

what is the single stage?

1. Self etching primer and sealer applied as a single solution
(Components supplied in two pouches that are mixed before application
Number of clinical steps are now 4:
1 -dispensing and/or mixing the two components
2- application to the enamel and dentine surface
3- drying
4- light curing)