1. Enamel & Dentin Adhesives

2. Introduction
 Advent of composite resin has shifed us to
the age of adhesive dentistry
 Adhesives have modified cavity preparation
concept from “ extension for prevention” to
“restriction with conviction” with the
invention of acid etching with 85%
phosphoric acid in 1955 by Bunocore.

3. Adhesion
 Refers to micromechanical coupling of
restoration to tooth structure
 Dental adhesive system consists of a
conditioner ,primer and bonding agent

4. hydrophobic
hydrophilic comp
dentin
Dentin
bonding
agent

5. Ideal Bonding Agent
 Eliminates post-operative sensitivity
 Thin film thickness
 No marginal discoloration
 Ease of use
 Reasonable shelf life
 Bond strength
 Moderate cost
(Christenseen 2005)

6. Generations of Adhesives
 8 generations :
 1st & 2nd without etching
 3rd acid etch,separate primer margin staining
 4th hybrid layer, concept of wet bonding
 5th primer and adhesive in 1 bottle
 6th self –etchprimers,decreased
sensitivity,bond strength lower than 5th
 7th All in one
 8th self-etch self-adhere flowable composite
(Optibond [Kerr]

7. New Classification
 Etch and Rinse system
 Self –Etch
- Two bottles applied separately
- Two bottles mixed as one solution
- All -in-one

9. Interaction With Dental Hard
Tissues
 With Enamel
 With Dentin
 Quality of dentin bonds thought to be
determined by the depth of demineralization
and extent of the diffusion and impregnation
of the monomer (Tay FR et al 2001)
 This zone of exposed collagen may be
unstable and subjected to hydrolysis (Sano H
et al)

10. - To avoid this ,self
etching systems that donot
require smear layer removal
these latest adhesives based
on simplification and
application time (Oper Dent
2003)

11. Smear layer 0.5-5Um

12. Self-Etching Scheme

13. Single bottle two-step total etch
(wet bonding technique)
-Acid etching
to remove
smear layer
- Application
of primed
adhesive

14. Total etch

15. Mode of Demineralization and
Hybridization

16. Adhesion depends upon
 Surface area
 High surface energy
 Wettability

26. Nano Interaction Zone
 Verse hybrid layer
 G Bond a type of the 7th generation

27. Ion Exchange Layer

28. • Although the smear layer thickness had no
effect on resin-dentin bond strength, thick
smear layers adversely affected the mean gap
width,The etch-and-rinse adhesive systems
showed higher microBS and lower mean gap
widths (Kenshima et al 2005)
• the one-step, low pH, acetone-based self-
etching adhesive promoted the higher bond
strength values, which were statistically
similar to those obtained with the two-step,
water-based self-etching adhesive (Pegado et
al 2010)

29. Glass Ionomer Adhesives
 Based on resin-modified GIC
 Conditioner polyalkanoic acid hybrid layer
0.5um
 The shear bond strength of the glass-ionomer
adhesive to dentin proved to be independent
of the smear layer thickness (El Askary et al
2008)

30.  Newer generations of adhesives appear to be
more tolerant of saliva contamination (Dunn
2004)
 Shear bond str. & numbers of gap-free
restorations increased significantly with
drying time (Jacobsen et al 2006)
 Following a correct application procedure,
the etch-and-rinse, self-etch and self-
adhesive luting agents are equally effective in
bonding to enamel and dentin (Van Merbeek
2007)

31.  Wettability is similar between self-etching
and total-etch adhesives.The smear layer
affects slightly the wettability of self-etching
adhesives (Rosales et al 2008)
 Enamel bonding was generally more effective
with phosphoric-acid etching. Enamel
bonding performance of 2-step self-etching
adhesives was improved when phosphoric
acid was applied on enamel selectively
(Frankenberger et al 2008)

32. Bond Strength

33. ThankYou