1. BONDING Dr. Raghuwar D Singh Associate Professor
Prosthodontic Department
King George’s Medical University UP, Lucknow

2. ADHESION Sound tooth structure must be conserved.
Optimal retention must be achieved.
Microleakage must be prevented.

3. MECHANISM OF ADHESION Factors in achieving adhesive bonds – Wetting
Interpenetration (formation of a hybrid zone)
Micromechanical Interlocking
Chemical bonding

4. ACID ETCHING TECHNIQUE –
Most effective ways of improving the marginal seal &
mechanical bonding b/w Resin and Enamel .
Mode Of Action ::
It creates micro-porosities by etching of the enamel .

5. Etching increase the surface area .
Etched enamel has a high surface energy and allows a
resin to wet the surface & penetrate into micro-
porosities.
Resin Tags are approx 6microm in diameter and micro m in length.

6. Acid Used :: 37 % Phosphoric acid is most commonly used acid .
Supplied in gel form .
Brush or Syringe is used for application on the
enamel .

7. Procedure :: Dry the enamel surface completely .
Length of application = 60 sec.
but may be 15 sec.
After etching , dried enamel shows white , frosted
appearance .
If enamel surface is contaminated, re-etching for 10 sec .

8. BONDING AGENTS:
Enamel bond agents
Dentin bond agents

9. ENAMEL BOND AGENTS:
Hydrophobic
Unfilled resin
Bis GMA
TEGDMA

10. DENTIN BOND AGENTS:
Dentin

11. Problems in bonding to dentin:
Dentin is a dynamic tissue that shows changes due to ageing, caries or restorative procedures.
Dentinal tubules are filled with dentinal fluid which constantly flow outward from the pulp.
Dentin has considerable amount of organic material & water.
Dentin is close to pulp, so different chemical used for bonding and etching may irritate the pulp.

12. role of smear layer :-
Whenever tooth surface is cut with hand or rotary instruments, it causes small particles of the cut tooth surface to the tooth producing the smear layer.
Smear layer is defined as any debris, calcific in nature produced by reduction or instrumentation of enamel of dentin or cementum.

13. Retention of smear layer:-
1) lowers dentin permeability
2) prevent decrease in bond strength
3) lowers effect of pulpal pressure on bond strength
** Recent generations adhesives involves modification of smear layer to facilitate bonding.

14. It has two phases -
Solid phase- made up of cutting debris, primarily
denaturated collagen and mineral.
Liquid phase- made up of tortuous fluid filled channels
around the cutting debris.
Bacteria entrapped in smear layer can survive and multiply beneath the restoration.

15. Conditioning of dentin:
It is defined as an alteration of dentin surface including the smear layer with the objective of producing a substrate capable of micromechanical and possibly chemical bonding to dentin adhesive.
Acid conditioners:
Phosphoric acid,
Citric acid,
Nitric acid,
Oxalic acid, and
Hydrochloric acid.

16. Chelators-
Remove the smear layer without decalcification or significant physical changes on underlying dentin substrate.
Best known chelator conditioner is EDTA.
Thermal conditioning-
Recent trend is to use lasers in conditioning of teeth.
Studies have conformed increased bond strengths with lased dentin compared to those with unlased dentin.

17. The molecule designed for dentin bonding were represented by an M-R-X molecule.
M- methacrylate group for bonding to resin matrix of composite resin
R- spacer such as hydrocarbon chain
X- functional group for bonding to organic or inorganic component of dentin.

18. ETCHENTS / CONDITIONERS
ORGANIC ACID:- Maleic acid, EDTA, Citric acid,
Tartaric acid.
POLYMERIC ACID:- Poly acrylic acid.
INORGANIC ACID:- Phosphoric acid, Nitric acid.

19. Hydrophilic
Primers/ Conditioners
Bonding liquid

20. PRIMERS
NTG-GMA
PMDM
BPDM
PENTA
HEMA

21. ADHESIVE RESINS Hydrophobic monomers - BIS-GMA UDMA Diluent - TEGDMA
Wetting agent -
HEMA

22. DENTIN BONDING AGENTS:
First generation
Second generation
Third generation
Forth generation
Fifth generation

23. MCQs:
Most effective way of improving the marginal seal and bonding between restorative resin and Enamel is:
1. Using adhesive
2. Acid etching
3. Using both adhesive and acid etching
4. None of the above

24. Most commonly used acid for acid etching technique:
1. 35% Phosphoric acid
2. 37% Phosporic acid
3. 37% Hydrochoric acid
4. 35% Citric acid

25. Chelators most commonly used to remove the smear layer:
1. EDTA
2. BIS GMA
3. HEMA
4. Oxalic acid

26. The nature of enamel bonding agents should be:
1. Hydrophilic
2. Hydrophobic
3. Depending on the condition of enamel
4. Neutral

27. The length of application of acid in acid etching technique should be:
1. 10 Second
2. 60 Second
3. 90 Second
Second

28. THANK YOU