1. Introduction to Adhesion
Professor
Professor
Mohsen Abielhassan

2. Lecture’s outlines What is meant by adhesive restorations?
Importance of adhesive restorations
Resin composite or amalgam ?
Glass ionomer as an adhesive restoration
Development of adhesive systems
Selection of adhesive systems
Successful adhesion
Bulk fil or incremental packing

4. Indications for adhesive dentistry:
Conservative restorations of class I, II, III, IV, V, VI carious or traumatic defects
Change shape and color of anterior teeth
Fractured tooth reattachment
Bond all indirect restorations
Provide foundations for crowns
Seal pits and fissures
Bond orthodontic brackets
Periodontal splints
Repair of restorations

5. Fundamental principles of bonding between two substrates:
Chemical
Micromechanical
Combined
Micromechanical depend on selective demineralization of inorganic…. Micropores and irregularities… into which adhesive agent infiltrate.. In situ polymerization

6. Adherend Adhesive Bonding Protocol
Adherend ….high SE, adhesive.. High flow..
Adherend ..enamel and dentin (changing)…..As long as adherend are different….the adhesive systems s be different … select the adhesion protocol suiting the case.. It makes sense…

7. Do you think it is easy…..
This is the virgin surface,…while for the prepared surface…highly mineralized.. HA.. DENSLY PACKED …forming unit,, rods,,for the uncut surface

8. This is the virgin surface,…while for the prepared surface…

9. Smear layer…..
Disturbed film of organic and hydroxyl-apatite particles, generally less than 2 μm thick.
Remove OR Dissolve OR Modify…
Etch and rinse adhesives….
Self etch adhesives..
Glass ionomer based adhesives..
Ultimately, this gelatinous layer could inhibit the formation of an impervious seal at the adhesive/dentin interface.
Based on dealing with this substrate adherent layer… the adhesive systems could be classified into…

10. 1) SMEAR LAYER REMOVING (etch and rinse):
Strong acid …. Removes smear layer and plugs.
Increases dentin permeability.
Deeper resin penetration….
Possible Nanoleakage….
Increased technique senstivity… steps.. senstivity &nanoleakage
Perfect for enamel but with dentin…

11. 2) Smear layer dissolving (self-etch):
Dissolving the smear layer and leaving the plugs..to seal dt… no rinsing rather the dissolved layer is incorporated in the hybrid layer thin with short tags.… 2 or 1 step.. Theoritically …simultanous dem and infiltration … no nanoleakage… exposed collagen… simplified.. No post oper ative senst.

12. Disadvantages of SE adhesives..
Insufficient bond durability………..smear layer incorporation into hybrid layer …..
Hydrophilicity…..hydrolytic degradation
Mild SE ………lower bond to enamel..

13. 3.SMEAR LAYER MODIFYING (glass ionomer):
10-20% conditioning with polyacrylic acid …… remove the smear layer…not the plugs…shallow demineralization (SHALLOW HYBRIDIZATION) ……. Leaving sufficient HA for (CHEMICAL ADHESION) … with the carboxylic groups of polyalkenoic acid.
Two fold

14. ADHESIVE INTERFACE:
The ideal hybrid layer would be characterized as a 3-dimensional polymer/collagen network
continuous and stable link between the bulk adhesive and dentin substrate.
There is substantial evidence to suggest that this ideal objective is not achieved.

15. The challenge in bonding to dental substrates:
Bonding is aiming to obtain reliable immediate bond strength between the synthetic resinous materials and the natural dental tissues and more importantly is the durability of such gained bond in the complicated fluctuating oral environment.

16. The challenge in bonding to dental substrates:
LONGEVITY OF THE BOND
Static
Dynamic
PERFECT IMMEDIATE BONDING
Oral environment
Stresses
Single concept… MINERALIZATION
Enamel
Dentin

17. Challenges For every step…..
Objective
Effective method
JUSTIFICATION
Result
I HAVE TO ASK MYSELF.. WHY I AM DOING LIKE THIS ….
SO IF IT WAS MODIFIED TO….