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CONTENTS
 INTRODUCTION
 ROLE OF ADHESIVE DENTISTRY
 CONCEPT OF ADHESION
ENAMEL ADHESION
DENTINE ADHESION
CHALLENGES IN ...
 DENTINE BONDING
CONDITIONING OF DENTINE
PRIMING OF DENTINE
 DENTINE BONDING AGENTS
CLASSIFICATION
GENERATIONS OF BONDIN...
 ROLE OF MICROLEAKAGE
 BIOCOMPATIBILITY
 ANTIBACTERIAL PROPERTY
 CLINICAL FACTORS IN DENTINE ADHESION
 NEWER CLINICAL...
INTRODUCTION
 There is much interest and activity in dentistry today with dentin bonding
agents.
 In the modern society,...
 Now more focus is laid upon conservative approach to the tooth
preparation.
 Therefore the introduction of adhesive res...
DEFINITION
 Adhesion is derived from Latin meaning "a state in which two surfaces are
held together by interfacial forces...
 Thus for the process of adhesion to occur , we need to understand the role
of following components:
 ADHESIVE
 ADHEREN...
 ADHESIVE is defined as a material , frequently a viscous fluid that
joins two substrates together by solidifying , resis...
 ADHESIVE STRENGTH is the measure of the load-bearing capacity of an
adhesive joint.
 Therefore the development of resin...
MECHANISM OF ADHESION:
MECHANICAL
ADSORPTION
DIFFUSION
COMBINATION
INDICATIONS FOR ADHESIVE DENTISTRY
 Restoration of class 1,2,3,4,5,6 carious lesions
 Change the shape & colour of anter...
ENAMEL ADHESION
 In 1955,Michael Buonocore described a clinical technique that used a diluted phosphoric acid to
etch the...
 Acid etching transforms smooth enamel into an irregular surface & increases its free surface
energy
 Application of a f...
ETCH PATTERN
 Enamel etching leads to the following types of micro morphological
patterns:
 TYPE 1 ETCH PATTERN-dissolut...
ETCHANT CONCENTRATION
 Buonocore used 30-40% phosphoric acid.
 Currently,37% phosphoric acid in gel form is used.
 Silv...
ETCH TIME
 Currently, an etching time of 15 seconds is used.
 An etching time of 60 seconds originally was recommended f...
Phosphoric acid is said to be a more aggressive acid,so alternative etchants have
been suggested:
 EDTA (24%; ph=7)
 Cit...
LASERS
 Adhesion to dental hard tissues after Er:YAG laser etching is inferior to that
obtained after conventional acid e...
Figure 1 Scanning electron microscopic images of dentin: (A)
rotary-prepared and acid-etched (3500!),
(B) laser-prepared (...
Figure 3 Separation of resin adhesive and
unaffected subsurface dentin from laser-
ablated, then acid-etched dentin.
Laser...
SEM photographs of 37% orthophosphoric acid, 10% maleic
acid, and Er,Cr:YSGG hydrokinetic laser-treated enamel are
shown i...
BOND STRENGTH
 Shear bond strength of composite to phosphoric acid etched enamel
exceeded 20 Mpa.
 According to studies,...
DENTIN ADHESION
 Bonding to dentin is challenging & difficult.
 Adhesion to dentin occurs by mechanical method,chemical ...
STRUCTURE OF DENTIN
 Enamel contains 90% of hydroxyapatite crystals whereas dentin has only
50% and the rest is constitut...
 Also the tubule diameter decreases from 2.37µm to 0.63µm near DEJ.
 Adhesion can also be affected by remaining dentin t...
WHAT IS SMEAR LAYER?
 It is the residual organic or inorganic components formed when a tooth is
prepared using a bur or o...
 COMPOSITION OF SMEAR LAYER:
 According to SEM studies done by Shulien TM(1988),it consists of:
 Small particles of min...
 Therefore optimal bonding can occur by:
A. Removal of smear layer by using etch and rinse adhesives.
B. Incorporation of...
 STRESSES AT THE RESIN-DENTIN INTERFACE:
 As composites polymerize,shrinkage occurs leading to stresses upto
7MPa.
 Whe...
DENTINE BONDING AGENTS
 It is defined as ”a thin layer of resin applied between conditioned dentin and resin
matrix of a ...
 Therefore the bonding agent should be hydrophilic to displace the water
,permitting it to penetrate the porosities in de...
CONDITIONING OF DENTIN
 It is the etching of dentin surface with acids or calcium chelators.
 So, when acid is applied t...
DURATION OF ETCHING ON DENTIN
Ideal duration is 15-20 seconds.
Increased duration: greater collapse
of collagen due to den...
PRIMING OF DENTIN
 It is the process of applying primers to the etched/conditioned dentin
surface to improve the diffusio...
Acid washing / rinsing
Removes smear layer
Dissolves HA
Drying shrinks remaining
Collagen polymer molecules
Rehydration / ...
Monomer penetration
Mechanism of dentine bonding
Monomer polymerisation
And collagen entanglement
CLASSIFICATION
1. HISTORICAL STRATEGIES
 FIRST GENERATION(1965)
 SECOND GENERATION(1978)
 THIRD GENERATION(1984)
2. CUR...
 Current strategies
 ETCH & RINSE ADESIVES SELF ETCH ADHESIVES
 THREE STEP-ETCH &RINSE ADHESIVE TWO STEP –ETCH & RINSE ...
 BASED ON MODERN ADHESION STRATEGY:
Van Meerbek et al(2001) suggested a classification based on adhesion strategy.
TOTAL ...
 BASED ON THE TREATMENT OF SMEAR LAYER:
 Smear layer modifying
 Smear layer removal
 Smear layer dissolving
DECADE BONDING AGENT FEATURES
1960s
1970s
FIRST GENERATION
SECOND GENERATION
• DENTIN ETCHING WAS CONTRAINDICATED
• ADHESI...
4-META Methacryloxy ethyl trimellitic
anhydride
NPG-GMA N-Phenylglycine glycidyl methacrylate
UDMA Urethane dimethacrylate...
 Most products use a three-component system consisting of a conditioner, primer, and
adhesive.
 1. CONDITIONER (CLEANSER...
 MAIN ACTIONS:
 Alters or removes the smear layer.
 demineralizes peritubular and intertubular dentin
 exposes collage...
 PRIMER
 bifunctional monomer in a volatile solvent such as acetone or alcohol
 examples of HEMA (hydroxyethyl methacry...
 MAIN ACTIONS:
 Links the hydrophilic dentin to the hydrophobic adhesive resin
 Promotes infiltration of demineralized ...
 ADHESIVE (BONDING RESIN):
 It is an unfilled or partially-filled resin; may contain some component of the primer (e.g.,...
FIRST GENERATION DENTIN BONDING AGENT
 It consisted of surface active co-monomer NPG-GMA(N-phenylglycine
glycidyl methacr...
 Clinical result:
 It had poor bond strength of 2-3MPa.
 Therefore when used to restore noncarious cervical lesions wit...
SECOND GENERATION DENTIN BONDING
AGENT:
 Introduced in 1978.
 They were based on phosphorous esters of methacrylate deri...
 ADVANTAGE:
 Bond strength was 3 times higher than the earlier ones.
 DISADVANTAGE:
 Bond strength was still lower aro...
 EXAMPLES:
 Clearfil Bond System(Kuraray,Japan)
 Scotchbond(3M ESPE)
 Bondlite(Kerr Corporation.CA)
 Prisma Universal...
THIRD GENERATION BONDING AGENT:
 It was a phosphate based material containing HEMA and a 10-carbon
molecule 10-MDP(10-met...
 Most of the other III generation bonding agents were designed not to
remove the smear layer but only to modify it and th...
COMPOSITION OF SOME III
GENERATION
DENTIN BONDING AGENTS
Adhesive
system
Etchant Primer Adhesive Bond
strength
Scotch Bond...
CLASSIFICATION
1. HISTORICAL STRATEGIES
 FIRST GENERATION(1965)
 SECOND GENERATION(1978)
 THIRD GENERATION(1984)
2. CUR...
CURRENT STRATEGIES FOR RESIN-DENTIN
BONDING
1. ETCH AND RINSE ADHESIVE:
The smear layer is considered to be an obstacle th...
 MECHANISM OF ACTION:
application of acid to dentin results in complete or partial removal of smear layer and
demineraliz...
 MOIST BONDING TECHNIQUE WITH ETCH AND RINSE ADHESIVE
• This was given by Kanca & Gwinett in 1990.
• Excess water on the ...
 How wet or dry should the dentin be?
 It should be hydrated that is clinically glistening and moist.
 How to achieve i...
 Why is complete drying of dentinal surface contraindicated?
 Vital dentin is moist.Therefore drying the dentin with air...
SEM of dentin that was acid etched with 37% phosphoric acid for 15s & rinsed
with water and then briefly air dried.there i...
SEM of dentin that was kept
moist after rinsing off etchant.
The abundant intertubular
porosity serves as a pathway for
th...
Scanning electron micrograph of
dentin collagen after acid etching
with 35% phosphoric acid.Dentin
was air dried.
The inte...
THREE STEP:ETCH&RINSE
ADHESIVES(FOURTH GENERATION)
IT CONSISTS OF
ETCHANT PRIMER ADHESIVE
 Here three components came into being:
 Phosphoric acid etchant(in gel form)
 Primer –it consisted of hydrophilic mono...
 Bonding agent:
 It consists of unfilled or filled resin which may be BisGMA(Bisphenol
glycidyl methacrylate),UDMA(ureth...
 ADVANTAGES:
 Higher bond strength of 17-24MPa.
 They show reliable and consistent results.
 DISADVANTAGES:
 Techniqu...
• BRAND NAMES-
• All Bond 2 & All Bond 3
• Optibond FL(Kerr Corporation)
• Adper Scotchbond Multi-purpose(3M ESPE)
• BOND ...
 CLINICAL STEPS INVOLVED:
 STEP1:application of etchant gel(37% phosphoric acid) for 15 seconds .
 STEP2:rinse the etch...
1st step:
-Total etching(removal of
smear layer)
Leaving free minerals on
surface
-Rinse surface
-Without drying of surfac...
WHAT IS HYBRID LAYER?
 DEFINITION
 “The structure formed in the dental hard tissue by demineralization of the
surface an...
ZONES
TOP LAYER MIDDLE LAYER BASE
TOP LAYER :loosely arranged collagen fibrils directed towards adhesive resin.
MIDDLE LAY...
TWO STEP :ETCH & RINSE ADHESIVES (FIFTH
GENERATION)
 This was developed to simplify the procedures involved in bonding.
...
It consists of
BOTTLE I BOTTLE II
(Etchant+Primer) (Adhesive)
BONDING TO DENTIN USING A SELF-ETCH PRIMER
 STEPS INVOLED ARE:
 STEP1:application of etchant gel.
 STEP2:rinse the etchant thoroughly and blot dry the substrate
(...
CLASSIFICATION
1. HISTORICAL STRATEGIES
 FIRST GENERATION(1965)
 SECOND GENERATION(1978)
 THIRD GENERATION(1984)
2. CUR...
SELF-ETCH ADHESIVES
 They are defined as “bonding systems which dissolve the smear layer and
create porosities in the und...
 The self-etching approach has been proposed in an effort to simplify the
dentin/enamel bonding systems.
 These material...
 Based on the acidity of self-etch primers & adhesives, they are classified
as:
 Weak- pH-2
 Medium pH-1.5
 Strong pH≤...
SELF-ETCH ADHESIVES
2 COMPONENT SELF-ETCH ADHESIVES 1 COMPONENT SELF-ETCH
ADHESIVES
(VI GENERATION) (VII GENERATION)
2 STE...
VI GENERATION BONDING AGENT
1. 2 STEP : 2 COMPONENT SELF-ETCHING ADHESIVES:
(NONRINSING CONDITIONERS OR SELF PRIMING ETCHA...
 Steps involved are:
 Application of bottle I(etchant +primer)
 After 10 s, application of bottle2 on tooth surface
 L...
2. ONE STEP:TWO COMPONENT-SELF-ETCH ADHESIVE:
 consists of- BottleI +Bottle II
 Bottle I:conditioner +primer
 Bottle II...
 Self etching primers are acidic in nature, leading to its penetration along
the aqueous channels found in the smear laye...
 In the sixth generation dentin bonding systems, acidic monomers like 4-
MET and 10-MDP are used ,thus dissolving the sme...
 ADVANTAGES
 No etching needed, therefore possibility of over-etching or over-drying is removed
 Less technique sensiti...
 TYPE 2 ( TWO BOTTLE 1 STEP SYSTEM):
 Liquid A contains primer.
 Liquid b contains a phosphoric acid modified resin.
 ...
SEVENTH GENERATION(early 2000s):
(SELF-ETCHING ADHESIVES)
 Here the etchant, primer and the adhesive resin are combined i...
 ADVANTAGES OF VII GENERATION DENTIN BONDING AGENTS:
 Lesser application time
 Decrease in errors with each step.
 Examples are:
 iBond(Heraeus kulzer)
 G bond(GC)
 XenoIV(Dentsply)
 Clearfil S3(Curare)
 XenoV+
XenoV+
iBond
COMPONENT FUNCTION
UDMA
(urethane dimethacrylate)
MATRIX COMPONENT
ETCHING & CONDITIONING OF ENAMEL & DENTIN
BONDING...
How is iBond applied?
1. Isolate tooth from saliva contamination during adhesive procedure
2. Clean the tooth prepation,re...
 Both the hydrophilic and the hydrophobic components are mixed in this system.
 Though this simplifies the clinical step...
 Advantages:
 Most time efficient application procedure.
 Unidose application,which prevents cross-contamination.
 Sim...
ONE COAT 7 BOND.
 7TH generation ,one component.
 Light cured self etching resin.
 High performance on any surface.
 H...
DECADE BONDING AGENT FEATURES
1960s
1970s
FIRST GENERATION
SECOND GENERATION
• DENTIN ETCHING WAS CONTRAINDICATED
• ADHESI...
RECENT ADVANCES :
UNIVERSAL ADHESIVE
 In 2012, the term “universal adhesive” has been given several definitions
which are...
 In November 2011, a new “ScotchBond Universal” was discovered.
Which needs a separate self-cure activator or a special a...
 In March 2012, a “All-Bond Universal” was discovered, which can be
used in:
i.total-etch, self-etch and selective etch t...
IS FUTURABOND DC-THE EIGTH
GENERATION
BONDING AGENT?
BASED ON THE TREATMENT OF SMEAR LAYER
SMEAR LAYER SMEAR LAYER SMEAR LAYER
MODIFYING REMOVAL DISSOLVING
SMEAR LAYER
 It was first suggested by Skinner in 1961.
 Coined by Boyde in 1963.
 0.5-2µm thick, granular
 Smear plug...
WHY IS THE PRESENCE OF SMEAR LAYER
DETRIMENTAL TO BONDING?
 It is a weak attachment to dentin and is brittle
 so it can ...
SMEAR LAYER REMOVAL
 DRAWBACK OF COMPLETE REMOVAL OF SMEAR LAYER:
Increases dentin permeability and flow of the dentinal ...
SMEAR LAYER MODIFYING
 Examples:
 II & III generation dentin bonding agents.
 Incorporation of smear layer inhibited pr...
SMEAR LAYER DISSOLVING
 Self-etching adhesives dissolve and include the smear layer in the
hybridization process.
 BASED...
Suresh Chandra et al.Comparative evaluation of self-etching
primers sixth, fourth& fifth generation dentin bonding systems...
 Thus aiding in monomer infiltration.
 Later the dentin is not washed therefore shrinkage of collagen is avoided.
 Acco...
BONDING EFFICACY OF VI AND VII
GENERATION BONDING AGENTS
 Manjula Nair, Joseph Paul et al. comparative evaluation of bond...
 Result:
VII>VI DBA
 Discussion:
 VI generation bonding agents have less bond strength to dentin due to high
acidity re...
 The retention of hydroxyapatite within the hybrid layer acts as receptor for
chemical bonding.
 Therefore this leads to...
Comparative evaluation of bonding efficacy of sixth,seventh
and eighth generation bonding agents:an in vitro study. Paul
J...
Figure 3: Specimens obtained after hard tis sue microtome sectioning Figure 4: Universal Testing Machine
CLINICAL APPLICATION OF SELF-ETCH
BONDING SYSTEMS
 Class V composite resin restoration using a
self-etch two step system
...
 ANTERIOR COMPOSITE RESTORATIONS(CLASS III,IV)
 POSTERIOR COMPOSITE RESIN RESTORATIONS
 Core build up restoration with light cured composite resin using two-step self-...
 RESTORATION OF PRIMARY TEETH
 Self-etch adhesives are an alternative to total etch systems.
 But ,the all in one adhes...
 CORE BUILD-UP WITH LIGHT-CURED COMPOSITE RESIN:
 CORE BUILD UP WITH FLOWABLE COMPOSITE….DEFECTIVE AMALGAM
RESTORATION…....
EXAMPLE OF A SELF-ETCH TWO STEP BONDING SYSTEM
INCLUDING ACTIVATOR(ADHESE/ADHESE DC ACTIVATOR)
FOR COMBINATION WITH DUAL-C...
In the combined post & core technique,the same dual cured composite resin is used for adhesive
post cementation & as core ...
 TREATMENT OF CERVICAL DENTIN HYPERSENSITIVITY
 PREVENTION OF ROOT SURFACE CARIES
 ADHESIVE CEMENTATION OF INDIRECT RES...
MICROLEAKAGE
 DEFINITION
 It is the passage of bacteria and their toxins between restoration
margins and tooth preparati...
 Therefore bonding the resin to a preparation with cavosurface margins in
enamel is the best way to prevent microleakage....
NANOLEAKAGE
 It is the small porosities in the hybrid layer or at the transition between the
hybrid layer and the dentin ...
NANOLEAKAGE UNDER ELECTRON MICROSCOPE.
Spotted pattern in the hybrid layer formed by one-step self-etch adhesive
Reticular...
ANTIBACTERIAL PROPERTY OF DENTIN
BONDING
AGENTS
 The development of adhesive systems have enabled variable cavity
designs...
 Thus cariogenic bacteria like Streptococcus mutans,Lactobacillus
acidophilus,Lactobacillus casei and Streptococcus saliv...
Amin S,Shetty HK,Varma RK,Amin V,Nair PM.Comparative
evaluation of antibacterial activity of total etch and self etch
adhe...
Sampath PB, Hegde MN, Hegde P.Assessment of the
antibacterial properties of newer dentin bonding agents. An in
vitro study...
Amin S,Shetty, HK,Varma et al. Comparative evaluation of antibacterial
activity of total etch and self etch adhesive syste...
 Result: Of all the materials tested, AP(Adper Prompt) showed the
maximum inhibitory action against S. mutans and L. acid...
BIOCOMPATIBILITY
 Biological testing of DBA is a delicate and complex process.
 Unlike most dental materials, many denti...
• A very limited number of reports have been published on the
biocompatibility of the first generation. Which may be due t...
International endodontic journal.
Volume 44 number 9 september 2011.
*Aim *
To evaluate the genotoxicity of four different adhesives, Clearfil SE Bond,SL Bond, i
Bond and Clearfil Protect Bon...
CLINICAL FACTORS AFFECTING ADHESION
 Flow of saliva and/or blood contamination
 Moisture contamination from handpiece or...
BONDING TO AMALGAM
 Bonding of amalgam restoration to tooth is still a debatable topic.
 The use of adhesive systems ben...
 Staninec M (1989) showed that retention with amalgam bonding is equal
to or superior to traditional means of mechanical ...
Failures can occur at various levels:
 between mineralised and demineralised dentin
 between demineralised dentin and bo...
CONCLUSION
In today’s era, numerous improvements in materials and
procedures have been made to meet the growing aesthetic...
 Thus the ideal bonding system should be biocompatible,
bond perfectly to enamel and dentin, have sufficient
strength to ...
BIBLIOGRAPHY
 STURDEVANT'S ART & SCIENCE OF DENTISTRY-4TH, 5TH & 6TH
EDITION
 PHILLIPS-SCIENCE OF DENTAL MATERIALS...11T...
 M.Bourbia, D.Ma, D.G Cvitkovitch et al.Cariogenic bacteria degrade
dental resin composite and adhesives.J Dent Res 92(11...
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dentin bonding agents
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dentin bonding agents

  1. 1. CONTENTS  INTRODUCTION  ROLE OF ADHESIVE DENTISTRY  CONCEPT OF ADHESION ENAMEL ADHESION DENTINE ADHESION CHALLENGES IN DENTINE ADHESION  ENAMEL BONDING STEPS FOR ENAMEL BONDING MECHANISM INVOLVED
  2. 2.  DENTINE BONDING CONDITIONING OF DENTINE PRIMING OF DENTINE  DENTINE BONDING AGENTS CLASSIFICATION GENERATIONS OF BONDING AGENTS FIRST GENERATION SECOND GENERATION THIRD GENERATIONS FOURTH GENERATION FIFTH GENERATION SIXTH GENERATION SEVENTH GENERATION
  3. 3.  ROLE OF MICROLEAKAGE  BIOCOMPATIBILITY  ANTIBACTERIAL PROPERTY  CLINICAL FACTORS IN DENTINE ADHESION  NEWER CLINICAL INDICATIONS OF DENTINE ADHESIVES DESENSITISATION ADHESIVE AMALGAM RESTORATIONS INDIRECT ADHESIVE RESTORATIONS  FAILURES IN DENTINE BONDING  SUMMARY  BIBLIOGRAPHY
  4. 4. INTRODUCTION  There is much interest and activity in dentistry today with dentin bonding agents.  In the modern society, aesthetics has become a major concern for every individual .Thus most of us desire for a perfect set of teeth.  Therefore, teeth that have been deformed or ravaged by dental diseases need to be restored to their natural form and colour.  Moreover, the classic concepts of tooth preparation advocated in the early 1900s have changed dramatically.
  5. 5.  Now more focus is laid upon conservative approach to the tooth preparation.  Therefore the introduction of adhesive restorative materials has reduced the need for an extensive tooth preparation.  In order to successfully accomplish this, dentin bonding systems have been introduced which bond the composite resin to the tooth structure.
  6. 6. DEFINITION  Adhesion is derived from Latin meaning "a state in which two surfaces are held together by interfacial forces like valence forces or interlocking forces or both". (The American Society for Testing and Materials)
  7. 7.  Thus for the process of adhesion to occur , we need to understand the role of following components:  ADHESIVE  ADHEREND  ADHESIVE STRENGTH
  8. 8.  ADHESIVE is defined as a material , frequently a viscous fluid that joins two substrates together by solidifying , resisting separation & transferring a load from one surface to the other.  ADHEREND is defined the surface to which an adhesive adheres.
  9. 9.  ADHESIVE STRENGTH is the measure of the load-bearing capacity of an adhesive joint.  Therefore the development of resin based restorative material has opened new vistas to a more conservative approach to caries management.
  10. 10. MECHANISM OF ADHESION: MECHANICAL ADSORPTION DIFFUSION COMBINATION
  11. 11. INDICATIONS FOR ADHESIVE DENTISTRY  Restoration of class 1,2,3,4,5,6 carious lesions  Change the shape & colour of anterior teeth(using full or partial veneer )  Seal pits and fissures  Bond orthodontic brackets  Desensitize exposed root surfaces  Bond amalgam restorations to tooth  Bond fractured segments of anterior teeth.  Bond pre-fabricated fibre or metal posts and cast posts.  Seal root canals during endodontic therapy.
  12. 12. ENAMEL ADHESION  In 1955,Michael Buonocore described a clinical technique that used a diluted phosphoric acid to etch the enamel surface to provide retention of unfilled, self-cured acrylic resins.  The resin would mechanically lock to the microscopically roughened enamel surface, forming small "tags" as it flowed into the 10-µm to 40-µm deep enamel microporosities and then polymerized.  The first clinical use of this technique was the placement of pit and fissure sealants.  The formation of resin micro tags within the enamel surface is the basis of RESIN-ENAMEL ADHESION.  The steps involved are:
  13. 13.  Acid etching transforms smooth enamel into an irregular surface & increases its free surface energy  Application of a fluid resin based material to the irregular etched surface , facilitates penetration of the resin into the surface aided by capillary action  Monomers in the material are polymerised and the material becomes interlocked with the enamel surface.
  14. 14. ETCH PATTERN  Enamel etching leads to the following types of micro morphological patterns:  TYPE 1 ETCH PATTERN-dissolution of prism cores without involvement of prism peripheries.  TYPE 2 ETCH PATTERN-PERIPHERAL ENAMEL IS DISSOLVED , but the cores are left intact.  TYPE 3 ETCH PATTERN-it is less distinct than the other two patterns.
  15. 15. ETCHANT CONCENTRATION  Buonocore used 30-40% phosphoric acid.  Currently,37% phosphoric acid in gel form is used.  Silverstone found that the application of 30-40% phosphoric acid resulted in a very retentive enamel surface.  >40% - Calcium salts are less dissolved - ETCH patterns with poorer definition.  <27% - Formation of dicalcium phosphate dihydrate - cannot be easily removed by rinsing.
  16. 16. ETCH TIME  Currently, an etching time of 15 seconds is used.  An etching time of 60 seconds originally was recommended for permanent enamel using 30-40% phosphoric acid.  However , studies show that a 15 second etch resulted in a similar surface roughness as that provided by a 60 second etch.
  17. 17. Phosphoric acid is said to be a more aggressive acid,so alternative etchants have been suggested:  EDTA (24%; ph=7)  Citric acid  Tannic acid  Maleic acid  Polyacrylic acid ALTERNATE ETCHANT SYSTEMS:  Lasers  Air abrasion-Al2O3 particles
  18. 18. LASERS  Adhesion to dental hard tissues after Er:YAG laser etching is inferior to that obtained after conventional acid etching.  Enamel and dentin surfaces prepared by Er:YAG laser etching show extensive subsurface fissuring that is unfavorable to adhesion. (J Prosthet Dent 2000;84:280-8.)  Adhesion to laser-ablated or laser-etched dentin and enamel was inferior to that of conventional rotary preparation and acid etching. ( Dental Materials (2005) 21, 616–624)
  19. 19. Figure 1 Scanning electron microscopic images of dentin: (A) rotary-prepared and acid-etched (3500!), (B) laser-prepared (9000!), and (C) laser-prepared and then acid- etched (3500!). (Fig. 1A) revealed a smoothsurface with tubule orifices devoid of smear plugs. The intertubular dentin is undisturbed. In contrast, SEM of a cross-section of laser-ablated, laser-etched dentin showed a highly irregular surface and fissuring. Areas of poor hybridization between composite and dentin suggest poor hybridization, or no hybridization. Laser-prepared dentin revealed surface scaling and flaking, along with peritubular cuffing (Fig. 1B). Acid- etching after laser ablation appeared to decrease some of the surface scaling and flaking (Fig. 1C).
  20. 20. Figure 3 Separation of resin adhesive and unaffected subsurface dentin from laser- ablated, then acid-etched dentin. Laser ablated,acid-etched dentin demonstrated areas of detachment From both the resin adhesive and the unaffected subsurface dentin (Fig. 3).
  21. 21. SEM photographs of 37% orthophosphoric acid, 10% maleic acid, and Er,Cr:YSGG hydrokinetic laser-treated enamel are shown in Figure 4. The enamel surface etched with 2 acid solutions and a laser system showed different results according to Silverstone’s10 etching patterns. • The 37% orthophosphoric acid removed the periphery core material but left the prism core relatively unaffected (type II), producing a very rough enamel surface. • The 10% maleic acid treatment resulted in preferential removal of prism core material and left the periphery intact (type I). • Er,Cr:YSGG hydrokinetic laser treated enamel showed a more random etching pattern in which adjacent areas of tooth surface correspond to types I and II, mixed with regions where the pattern could not be related to prism structure. There was no recrystallization or melting observed
  22. 22. BOND STRENGTH  Shear bond strength of composite to phosphoric acid etched enamel exceeded 20 Mpa.  According to studies,a minimum of 17-21MPa of bond strength is needed to prevent the disruption of the bond between the tooth and composite.
  23. 23. DENTIN ADHESION  Bonding to dentin is challenging & difficult.  Adhesion to dentin occurs by mechanical method,chemical or both.  But the main method is by penetration of adhesive monomers into collagen fibrils which are exposed post acid etching.  Structural differences exist between enamel & dentin.  Therefore the following reasons account for challenges faced in dentin adhesion:  STRUCTURE OF DENTIN  SMEAR LAYER  STRESSES AT RESIN-DENTIN INTERFACE
  24. 24. STRUCTURE OF DENTIN  Enamel contains 90% of hydroxyapatite crystals whereas dentin has only 50% and the rest is constituted by water(25%) and type I collagen(25% by volume).  Dentinal tubules exert pressure of 25-30mmHg, thus creating decreased stability of bond between composite resin and dentin.  The number of dentinal tubules decreases from about 45000 near the pulp to 20000 near DEJ
  25. 25.  Also the tubule diameter decreases from 2.37µm to 0.63µm near DEJ.  Adhesion can also be affected by remaining dentin thickness(RDT) as bond strength is greater for superficial dentin and its lesser for deeper dentin
  26. 26. WHAT IS SMEAR LAYER?  It is the residual organic or inorganic components formed when a tooth is prepared using a bur or other instrument. (Sturdevant’s Art & Science of operative dentistry,4th edition)  It is 1-10 µm thick .
  27. 27.  COMPOSITION OF SMEAR LAYER:  According to SEM studies done by Shulien TM(1988),it consists of:  Small particles of mineralized collagen matrix  Inorganic tooth preparation  Saliva  Blood  Bacteria  According to branstroem,the organic component consisted of coagulated proteins from collagen denatured by frictional heat of cutting.
  28. 28.  Therefore optimal bonding can occur by: A. Removal of smear layer by using etch and rinse adhesives. B. Incorporation of smear layer into bonding layer by self-etch adhesives Complete removal of smear layer increases the dentin permeability by 90%.
  29. 29.  STRESSES AT THE RESIN-DENTIN INTERFACE:  As composites polymerize,shrinkage occurs leading to stresses upto 7MPa.  When the composite is bonded only to one surface,stresses are relieved by flow from the unbended surface.  Davidson et al. postulated that minimum bond strength of 17-20 MPa to enamel and dentin is needed to resist contraction forces of resin composite materials.  In the present study, both the self-etching adhesives showed optimal bond strength values greater than 20 MPa for both uncontaminated and contaminated dentin.
  30. 30. DENTINE BONDING AGENTS  It is defined as ”a thin layer of resin applied between conditioned dentin and resin matrix of a composite.”  The term dentine bonding agents is no longer relevant as current bond agents bond to enamel and dentine.  Due to acid –etching ,micro leakage or loss of retention is not a hazard at the resin- enamel interface but its encountered at the resin-dentine interface.  Due to the differences in the composition of enamel and dentine,developing agents that will adhere to dentine was challenging due to the following reasons:  The high water content interferes with bonding.  Presence of a smear layer on the dentine surface.
  31. 31.  Therefore the bonding agent should be hydrophilic to displace the water ,permitting it to penetrate the porosities in dentine and react with the inorganic/organic components.  But, restorative resins are hydrophobic, therefore the bonding agent should contain both hydrophilic and hydrophobic components.  The hydrophilic part bonds with either calcium or collagen whereas the hydrophobic part bonds with the restorative resin.
  32. 32. CONDITIONING OF DENTIN  It is the etching of dentin surface with acids or calcium chelators.  So, when acid is applied to it, dissolution of hydroxyapatite crystals in intertubular dentin and outer surface of peritubular dentin occurs  Ultimately, the smear layer gets removed and collagen fibrils are exposed.  Materials used are: 37% phosphoric acid  nitric acid  citric acid  EDTA(ethylene diamine tetra-acetic acid)
  33. 33. DURATION OF ETCHING ON DENTIN Ideal duration is 15-20 seconds. Increased duration: greater collapse of collagen due to denaturation. Decreased monomer infiltration. Decreased duration: insufficient depth of etching.
  34. 34. PRIMING OF DENTIN  It is the process of applying primers to the etched/conditioned dentin surface to improve the diffusion of the adhesive resin into moist and demineralized dentin  Primer solution is a mixture of monomers with hydrophilic and hydrophobic components dissolved in organic solvent  Priming agents are HEMA(hydroxyethyl methacrylate) and 4-META(4- methacryloxyethyl trimellitae anhydride)
  35. 35. Acid washing / rinsing Removes smear layer Dissolves HA Drying shrinks remaining Collagen polymer molecules Rehydration / priming Swells collagen Mechanism of dentine bonding
  36. 36. Monomer penetration Mechanism of dentine bonding Monomer polymerisation And collagen entanglement
  37. 37. CLASSIFICATION 1. HISTORICAL STRATEGIES  FIRST GENERATION(1965)  SECOND GENERATION(1978)  THIRD GENERATION(1984) 2. CURRENT STRATEGIES  ETCH & RINSE ADESIVES i. THREE STEP-ETCH &RINSE ADHESIVE(FOURTH GENERATION) ii. TWO STEP –ETCH & RINSE ADHESIVE(FIFTH GENERATION)  SELF ETCH ADHESIVES  TWO COMPONENT –SELF ETCH ADHESIVE(SIXTH GENERATION) o TWO STEP-TWO COMPONENT –SELF ETCH ADHESIVE o ONE STEP –TWO COMPONENT - SELF ETCH ADHESIVE  SINGLE COMPONENT-ONE STEP-SELF ETCH ADHESIVE(SEVENTH GENERATION)
  38. 38.  Current strategies  ETCH & RINSE ADESIVES SELF ETCH ADHESIVES  THREE STEP-ETCH &RINSE ADHESIVE TWO STEP –ETCH & RINSE ADHESIVE (FOURTH GENERATION) (FIFTH GENERATION) TWO COMPONENT –SELF ETCH ADHESIVE SINGLE COMPONENT- ADHESIVE(SEVENTH ( SIXTH GENERATION ) ( SEVENTH GENERATION) TWO STEP-TWO COMPONENT –SELF ETCH ADHESIVE ONE STEP –TWO COMPONENT - SELF ETCH ADHESIVE
  39. 39.  BASED ON MODERN ADHESION STRATEGY: Van Meerbek et al(2001) suggested a classification based on adhesion strategy. TOTAL ETCH SELF ETCH TWO STEP MILD THREE STEP ADHESIVES MODERATE INTERMEDIARY STRONG TYPE OF ADHESIVE STEPS INVOLVED ETCH AND RINSE ADHESIVES THREE STEP ADHESIVE:FOURTH GENERATION TWO STEP ADHESIVE:FIFTH GENERATION SELF ETCH ADHESIVES TWO STEP ADHESIVE:SIXTH GENERATION ONE STEP ADHESIVE:SEVENTH GENERATION
  40. 40.  BASED ON THE TREATMENT OF SMEAR LAYER:  Smear layer modifying  Smear layer removal  Smear layer dissolving
  41. 41. DECADE BONDING AGENT FEATURES 1960s 1970s FIRST GENERATION SECOND GENERATION • DENTIN ETCHING WAS CONTRAINDICATED • ADHESION WAS TO SMEAR LAYER • WEAK BOND STRENGTH 1980s THIRD GENERATION • ETCHING ENAMEL & DENTIN • PRIMING-A SECOND STEP WAS DONE • BETTER BOND STRENGTH EARLY 1990s FOURTH GENERATION • TOTAL ETCH CONCEPT WAS INTRODUCED • WET BONDING & HYBRID LAYER CONCEPTS INTRODUCED • MULTIPLE TECHNIQUE SENSITIVE CLINICAL STEPS MID 1990s FIFTH GENERATION • PRIMER & ADHESIVE COMBINED IN ONE BOTTLE • HIGHER BOND STRENGTHS LATE 1990s SIXTH GENERATION • INTRODUCTION OF SELF-ETCHING PRIMERS • POST OPERATIVE SENSITIVITY WAS REDUCED • LOWER BOND STRENGTHS EARLY 2000s SEVENTH GENERATION • ALL IN ONE/ONE STEP BOND CONCEPT INTRODUCED • BOND STRENGTH LOWER THAN 4TH & 5TH GENERATIONS
  42. 42. 4-META Methacryloxy ethyl trimellitic anhydride NPG-GMA N-Phenylglycine glycidyl methacrylate UDMA Urethane dimethacrylate TEGDMA Triethyleneglycol dimethacrylate MDPB 10-Methacryloyl oxydodecyl pyridinium bromide MDP 10-Methacryloyl oxydecyl dihydrogen phosphate PENTA Dipentaerythritol pentaacrylate monophosphate TYPE OF RESIN EXPANSION Bis-GMA Bisphenol A glycidyl methacrylate HEMA 2-hydroxyethyl methacrylate
  43. 43.  Most products use a three-component system consisting of a conditioner, primer, and adhesive.  1. CONDITIONER (CLEANSER, ETCHANT) –  weak organic acid (e.g., maleic acid),  a low concentration of a stronger inorganic acid (e.g., phosphoric or nitric acid)  a chelating agent (e.g., EDTA).
  44. 44.  MAIN ACTIONS:  Alters or removes the smear layer.  demineralizes peritubular and intertubular dentin  exposes collagen fibrils --demineralizes up to a depth of 7.5 microns.  peritubular dentin is etched more deeply than the intertubular dentin increases dentin permeability.
  45. 45.  PRIMER  bifunctional monomer in a volatile solvent such as acetone or alcohol  examples of HEMA (hydroxyethyl methacrylate), NMSA (N-methacryloyl-5- aminosalicylic acid), NPG (N-phenylglycine), PMDM (pyromellitic diethylmethacrylate), and 4-META (4- methacryloxyethyl trimellitate anhydride).
  46. 46.  MAIN ACTIONS:  Links the hydrophilic dentin to the hydrophobic adhesive resin  Promotes infiltration of demineralized peritubular and intertubular dentin  increases wettability of the conditioned dentin surface
  47. 47.  ADHESIVE (BONDING RESIN):  It is an unfilled or partially-filled resin; may contain some component of the primer (e.g., HEMA) in an attempt to promote increased bond strength.  MAIN ACTIONS:  Combines with the primer s monomers to form a resin-reinforced hybrid layer ( resin-dentin interdiffusion zone ) 1 to 5 microns thick.  Forms resin tags to seal the dentin tubules
  48. 48. FIRST GENERATION DENTIN BONDING AGENT  It consisted of surface active co-monomer NPG-GMA(N-phenylglycine glycidyl methacrylate)  MECHANISM OF ACTION:  This co-monomer could chelate with calcium on the tooth surface to generate chemical bonds of resin to calcium.  Example:  Cervident(S S White burs,Lakewood)
  49. 49.  Clinical result:  It had poor bond strength of 2-3MPa.  Therefore when used to restore noncarious cervical lesions without mechanical retention.
  50. 50. SECOND GENERATION DENTIN BONDING AGENT:  Introduced in 1978.  They were based on phosphorous esters of methacrylate derivatives.  MECHANISM OF ACTION:  Adhesion was by means of ionic interaction between the negatively charged phosphate groups & positively charged calcium in the smear layer.  Advantage:  Bond strength was 3 times higher than the earlier ones.  Disadvantage:  Bond strength was still lower around 5-6 Mpa.  Clinical failure due to the bonding instability in the wet oral environment & their primary bonding to the smear layer and not the dentin.
  51. 51.  ADVANTAGE:  Bond strength was 3 times higher than the earlier ones.  DISADVANTAGE:  Bond strength was still lower around 5-6 Mpa.  Clinical failure due to the bonding instability in the wet oral environment & their primary bonding to the smear layer and not the dentin.
  52. 52.  EXAMPLES:  Clearfil Bond System(Kuraray,Japan)  Scotchbond(3M ESPE)  Bondlite(Kerr Corporation.CA)  Prisma Universal Bond(Dentsply)
  53. 53. THIRD GENERATION BONDING AGENT:  It was a phosphate based material containing HEMA and a 10-carbon molecule 10-MDP(10-methacryloyloxy decyl dihydrogen phosphate)  These were introduced with Clearfil New Bond in 1984.  MECHANISM OF ACTION:  The concept of phosphoric acid etching of dentin before the application of a phosphate ester type of bonding agent was put forward by FUSAYAMA et al in 1979
  54. 54.  Most of the other III generation bonding agents were designed not to remove the smear layer but only to modify it and therefore allow the penetration of acidic monomers like pheny-P or PENTA(dipentaerythritol penta-acrylate monophosphate)  EXAMPLES:  Clearfil New Bond(Kuraray)  Scotchbond 2(3M ESPE)
  55. 55. COMPOSITION OF SOME III GENERATION DENTIN BONDING AGENTS Adhesive system Etchant Primer Adhesive Bond strength Scotch Bond 2 2.5% maleic acid + 55% HEMA HEMA Bis GMA 8.8 Mpa Tenure Oxalate bonding system aluminium oxalate in 2.5% nitric acid NPG-GMA. BisGMA, TEGDMA 15 Mpa This generation attempted to deal with both the smear layer and dentinal fluid, with following 2 approaches: i. Smear layer modification to improve its properties. ii. Remove s.layer without disturbing the smear plugs that occlude dentinal tubules.
  56. 56. CLASSIFICATION 1. HISTORICAL STRATEGIES  FIRST GENERATION(1965)  SECOND GENERATION(1978)  THIRD GENERATION(1984) 2. CURRENT STRATEGIES  ETCH & RINSE ADESIVES i. THREE STEP-ETCH &RINSE ADHESIVE(FOURTH GENERATION) ii. TWO STEP –ETCH & RINSE ADHESIVE(FIFTH GENERATION)  SELF ETCH ADHESIVES  TWO COMPONENT –SELF ETCH ADHESIVE(SIXTH GENERATION) o TWO STEP-TWO COMPONENT –SELF ETCH ADHESIVE o ONE STEP –TWO COMPONENT - SELF ETCH ADHESIVE  SINGLE COMPONENT-ONE STEP-SELF ETCH ADHESIVE(SEVENTH GENERATION)
  57. 57. CURRENT STRATEGIES FOR RESIN-DENTIN BONDING 1. ETCH AND RINSE ADHESIVE: The smear layer is considered to be an obstacle that must be removed to permit resin bonding to dentin. The next generation of dentin adhesives was introduced for use on acid – etched dentin. The clinical technique involves simultaneous application of an acid to enamel & dentin.This was called as total-etch technique.
  58. 58.  MECHANISM OF ACTION: application of acid to dentin results in complete or partial removal of smear layer and demineralization of dentin Intertubular & peritubular dentin are demineralised,thus exposing collagen fibres & increasing microporosity of intertubular dentin 7.5µm of dentin is demineralised Primer increases the free surface energy of dentin Formation of resin tags and hybrid layer.
  59. 59.  MOIST BONDING TECHNIQUE WITH ETCH AND RINSE ADHESIVE • This was given by Kanca & Gwinett in 1990. • Excess water on the substrate that is the tooth surface is not indicated due to the following reasons: • Swelling of collagen occurs leading to the decrease in the space available for resin penetration • Secondly, it dilutes the primer. • Thirdly, when priming is done in such conditions, phase separation of hydrophobic and hydrophilic components occur leading to blister & globule formation at the resin-dentin interface. • Thus these water blisters may compress when the restoration is under,forcing dentinal fluid towards pulp and causing post-operative sensitivity.
  60. 60.  How wet or dry should the dentin be?  It should be hydrated that is clinically glistening and moist.  How to achieve it?  After etching and rinsingblot the excess water dry with a sponge & which shoulbe touched to the surface of water and not pressed against dentin.
  61. 61.  Why is complete drying of dentinal surface contraindicated?  Vital dentin is moist.Therefore drying the dentin with air would cause collapse of dentinal collagen fibrils and thus leading to its shrinkage.  The interfibrillar space should be left open and hydrated for effective resin infiltration.
  62. 62. SEM of dentin that was acid etched with 37% phosphoric acid for 15s & rinsed with water and then briefly air dried.there is disappearance of spaces between collagen fibrils in top 1µm of demineralized zone that extends 5µm.although liquid monomers can permeate the tubules,it cannot pass through the spaces between collagen fibrils in intertubular dentin. TL-dentinal tubule.
  63. 63. SEM of dentin that was kept moist after rinsing off etchant. The abundant intertubular porosity serves as a pathway for the penetration of the dentin adhesive . T, dentinal tubule.
  64. 64. Scanning electron micrograph of dentin collagen after acid etching with 35% phosphoric acid.Dentin was air dried. The intertubular porosity disappeared due to collapse of collagen secondary to the evaporation of water.
  65. 65. THREE STEP:ETCH&RINSE ADHESIVES(FOURTH GENERATION) IT CONSISTS OF ETCHANT PRIMER ADHESIVE
  66. 66.  Here three components came into being:  Phosphoric acid etchant(in gel form)  Primer –it consisted of hydrophilic monomers in ethanol , acetone or water.  Primer is a bifunctional molecule having a hydrophilic and a hydrophobic part.the former attaches to tooth whereas the latter attaches to composite resin.  Examples:HEMA NTG-GMA PENTA
  67. 67.  Bonding agent:  It consists of unfilled or filled resin which may be BisGMA(Bisphenol glycidyl methacrylate),UDMA(urethane dimethacrylate) with TEGDMA & HEMA(2-hydroxyethyl methacrylate).  Thus after the application of primer and bonding agent to etched surface aids in their penetration into intertubular dentin to form a resin-dentin inter diffusion zone called HYBRID LAYER which was introduced by Nakabayashi in 1982.
  68. 68.  ADVANTAGES:  Higher bond strength of 17-24MPa.  They show reliable and consistent results.  DISADVANTAGES:  Technique sensitive  Time consuming procedure  Over wetting or over drying of dentin may occur
  69. 69. • BRAND NAMES- • All Bond 2 & All Bond 3 • Optibond FL(Kerr Corporation) • Adper Scotchbond Multi-purpose(3M ESPE) • BOND STRENGTH- • 17-30 Mpa.
  70. 70.  CLINICAL STEPS INVOLVED:  STEP1:application of etchant gel(37% phosphoric acid) for 15 seconds .  STEP2:rinse the etchant thoroughly and blot dry the substrate (moist bonding technique)  STEP3:application of primer (bottle 1) on the substrate.  STEP4:application of adhesive(bottle 2)on the tooth substrate.  STEP5: light cure .
  71. 71. 1st step: -Total etching(removal of smear layer) Leaving free minerals on surface -Rinse surface -Without drying of surface (residual water left) 2nd step : adding primer 3rd step: Adding adhesive resin & then composite Composite Smear layer Residual water Primer Adhesive resin
  72. 72. WHAT IS HYBRID LAYER?  DEFINITION  “The structure formed in the dental hard tissue by demineralization of the surface and the sub-surface followed by infiltration of monomers & subsequent polymerization.” ( Nakabayashi,1982)  It is a hybrid combination of the above two. It is a process which creates a molecular level interfacebetween dentin and composite resin.
  73. 73. ZONES TOP LAYER MIDDLE LAYER BASE TOP LAYER :loosely arranged collagen fibrils directed towards adhesive resin. MIDDLE LAYER: collagen fibrils separated by electron lucent spaces(10-20nm) represent areas in which HA crystals have been replaced by resin due to hybridization. BASE : partially demineralized dentin.
  74. 74. TWO STEP :ETCH & RINSE ADHESIVES (FIFTH GENERATION)  This was developed to simplify the procedures involved in bonding.  Therefore , the primer and the bonding agent is present in a single bottle.  COMPONENTS:  ETCHANT GEL + PRIMER & ADHESIVE
  75. 75. It consists of BOTTLE I BOTTLE II (Etchant+Primer) (Adhesive)
  76. 76. BONDING TO DENTIN USING A SELF-ETCH PRIMER
  77. 77.  STEPS INVOLED ARE:  STEP1:application of etchant gel.  STEP2:rinse the etchant thoroughly and blot dry the substrate (moist bonding technique)  STEP3:application of primer and adhesive (single bottle)  STEP4:light cure .  BRAND NAMES:  Prime & Bond NT(Dentsply)  Adper single bond2  ExciTE(Ivoclar,Vivadent)  One coat Bond  XP Bond
  78. 78. CLASSIFICATION 1. HISTORICAL STRATEGIES  FIRST GENERATION(1965)  SECOND GENERATION(1978)  THIRD GENERATION(1984) 2. CURRENT STRATEGIES  ETCH & RINSE ADESIVES i. THREE STEP-ETCH &RINSE ADHESIVE(FOURTH GENERATION) ii. TWO STEP –ETCH & RINSE ADHESIVE(FIFTH GENERATION)  TWO COMPONENT –SELF ETCH ADHESIVE(SIXTH GENERATION) o TWO STEP-TWO COMPONENT –SELF ETCH ADHESIVE o ONE STEP –TWO COMPONENT - SELF ETCH ADHESIVE  SINGLE COMPONENT-ONE STEP-SELF ETCH ADHESIVE(SEVENTH GENERATION)
  79. 79. SELF-ETCH ADHESIVES  They are defined as “bonding systems which dissolve the smear layer and create porosities in the underlying dental substrates without needing an extra conditioning agent(eg:phosphoric acid) to be applied in a single step. (Quintessence International,vol(8), nov-dec2013)  No separate etching step is needed.  ADVANTAGES:  Decrease in the number of steps  Less technique sensitive.
  80. 80.  The self-etching approach has been proposed in an effort to simplify the dentin/enamel bonding systems.  These materials combine tooth surface etching and priming steps into one single procedure.  The elimination of separate etching and rinsing steps simplified the bonding technique and has been responsible for the increased popularity of these systems in daily practice33
  81. 81.  Based on the acidity of self-etch primers & adhesives, they are classified as:  Weak- pH-2  Medium pH-1.5  Strong pH≤1  Most commonly pH ranges from1.3-2.7
  82. 82. SELF-ETCH ADHESIVES 2 COMPONENT SELF-ETCH ADHESIVES 1 COMPONENT SELF-ETCH ADHESIVES (VI GENERATION) (VII GENERATION) 2 STEP & 2 COMPONENT I STEP BUT 2 COMPONENT
  83. 83. VI GENERATION BONDING AGENT 1. 2 STEP : 2 COMPONENT SELF-ETCHING ADHESIVES: (NONRINSING CONDITIONERS OR SELF PRIMING ETCHANTS) MECHANISM OF ACTION:  These acidic primers contain phosphonated resin molecule that performs two function:  Etching and priming of enamel  Incorporating smear plugs into resin tags.
  84. 84.  Steps involved are:  Application of bottle I(etchant +primer)  After 10 s, application of bottle2 on tooth surface  Light cure  BRAND NAMES:  Clearfil SE Bond(Kuraray,Japan)  AdheSE(Ivoclar-Vivadent)  Optibond Solo Plus Self-etch(Kerr Corp)
  85. 85. 2. ONE STEP:TWO COMPONENT-SELF-ETCH ADHESIVE:  consists of- BottleI +Bottle II  Bottle I:conditioner +primer  Bottle II: adhesive resin  Both have to be mixed prior to application on tooth surface.  BRAND NAMES:  Xeno III(Dentsply)  One up bond(Tokuyama)  Prompt L bond(3M ESPE)
  86. 86.  Self etching primers are acidic in nature, leading to its penetration along the aqueous channels found in the smear layer and widening them.  These offer a simpler clinical step when compared to the tota;l etch adhesive systems.  self etching primers contain acidic esters like HEMA,TEGDMA,MDP.  These primers are similar to those found in third generation dentin bonding systems, the only difference being that in the latter ones only milder acids were used leading to inability to etch beyond the smear layer.
  87. 87.  In the sixth generation dentin bonding systems, acidic monomers like 4- MET and 10-MDP are used ,thus dissolving the smear layer.  When the concentration of acidic monomers increasd from 5-10% wt %(III generation dentin bonding agent) to 30-40% (VI generation dentin bonding agent) and dissolved in 30-40% HEMA, pH-1-2 was developed which aided in etching through smear layer.
  88. 88.  ADVANTAGES  No etching needed, therefore possibility of over-etching or over-drying is removed  Less technique sensitive.  Self-etch adhesives are less likely to result in discrepancy between depth of demineralization and depth of resin infiltration as both the processes are done simultaneously.  Less time consuming  DISADVANTAGES  Decreased shelf life  Incompatible with chemical cure composites.  Self-etch adhesives that are currently available do not etch as efficiently as phosphoric acid, especially if the enamel has not been instrumented.
  89. 89.  TYPE 2 ( TWO BOTTLE 1 STEP SYSTEM):  Liquid A contains primer.  Liquid b contains a phosphoric acid modified resin.  Both are mixed before application.  Eg:Xeno 3(Dentsply),Adper-prompt L-pop(3M).
  90. 90. SEVENTH GENERATION(early 2000s): (SELF-ETCHING ADHESIVES)  Here the etchant, primer and the adhesive resin are combined into one bottle .  In vitro studies have shown that tooth-restoration interface created when using self etching adhesives do not eliminate the micro leakage and bacterial penetration, which can lead to secondary caries.  (Kakar S,Goswami M,nagar R.Dentin bonding agents-2 Recent trials. World J Dent2012;3(1);115-118.
  91. 91.  ADVANTAGES OF VII GENERATION DENTIN BONDING AGENTS:  Lesser application time  Decrease in errors with each step.
  92. 92.  Examples are:  iBond(Heraeus kulzer)  G bond(GC)  XenoIV(Dentsply)  Clearfil S3(Curare)  XenoV+ XenoV+
  93. 93. iBond COMPONENT FUNCTION UDMA (urethane dimethacrylate) MATRIX COMPONENT ETCHING & CONDITIONING OF ENAMEL & DENTIN BONDING TO COLLAGEN VIA HYDROGEN BONDING BONDING TO CALCIUM IONS VIA CHELATION COMPLEXES 4-META (4-methyloxyethyl trimellitic acid) MATRIX COMPONENT CROSS-LINKING WATER SOLVENT FOR MONOMERS PROVIDES WATER FOR ETCHING CAMPHORQUINONE PHOTOINITIATORS GLUTARALDEHYDE DISINFECTANT/DESENSITIZER STABILIZERS
  94. 94. How is iBond applied? 1. Isolate tooth from saliva contamination during adhesive procedure 2. Clean the tooth prepation,removing all debris with water. 3. Saturate the microbrush with iBond liquidfrom the bottle or single dose vial. 4. Apply 3 consecutive coats of iBond to enamel & dentin 5. Use gentle air pressure to remove excess solvent 6. Cure for 20s with curing light 7. Place the composite resin.
  95. 95.  Both the hydrophilic and the hydrophobic components are mixed in this system.  Though this simplifies the clinical steps,it has following shortcomings:  Due to the complex nature of this solution,they are more prone to phase separation.  It forms droplets within the adhesive layer.  This adhesive layer acts as a semi-permeable membrane permitting bi-directional water currents.  Thus these bonding agents show much reduced bond strength when compared to the fourth,fifth,and sixth generation of bonding agents.
  96. 96.  Advantages:  Most time efficient application procedure.  Unidose application,which prevents cross-contamination.  Simultaneous demineralisation & resin penetration.  Less sensitivity to dentin wetness conditions.  Disadvantages:  Reduced shelf life.  Less sealing capacity.  Least bond strength.  Incompatibility with auto/chemical curing composites.
  97. 97. ONE COAT 7 BOND.  7TH generation ,one component.  Light cured self etching resin.  High performance on any surface.  Has a fast application in 35 seconds.  On wet surfaces maintains uniform composition, producing an effective bond.
  98. 98. DECADE BONDING AGENT FEATURES 1960s 1970s FIRST GENERATION SECOND GENERATION • DENTIN ETCHING WAS CONTRAINDICATED • ADHESION WAS TO SMEAR LAYER • WEAK BOND STRENGTH 1980s THIRD GENERATION • ETCHING ENAMEL & DENTIN • PRIMING-A SECOND STEP WAS DONE • BETTER BOND STRENGTH EARLY 1990s FOURTH GENERATION • TOTAL ETCH CONCEPT WAS INTRODUCED • WET BONDING & HYBRID LAYER CONCEPTS INTRODUCED • MULTIPLE TECHNIQUE SENSITIVE CLINICAL STEPS MID 1990s FIFTH GENERATION • PRIMER & ADHESIVE COMBINED IN ONE BOTTLE • HIGHER BOND STRENGTHS LATE 1990s SIXTH GENERATION • INTRODUCTION OF SELF-ETCHING PRIMERS • POST OPERATIVE SENSITIVITY WAS REDUCED • LOWER BOND STRENGTHS EARLY 2000s SEVENTH GENERATION • ALL IN ONE/ONE STEP BOND CONCEPT INTRODUCED • BOND STRENGTH LOWER THAN 4TH & 5TH GENERATIONS
  99. 99. RECENT ADVANCES : UNIVERSAL ADHESIVE  In 2012, the term “universal adhesive” has been given several definitions which are: a)Can be used in total-etch, self-etch, and selective etch techniques; b)Can be used with light-cure, self-cure, and dual-cure materials (without the separate activators); c)Can be used for both direct and indirect substrates; d)Can bond to all dental substrates, such as dentin, enamel, metal, ceramic, porcelain, and zirconia.
  100. 100.  In November 2011, a new “ScotchBond Universal” was discovered. Which needs a separate self-cure activator or a special amine-free dual- cure cement when in use with dual-cure or self-cure materials, hence not a truly “universal” adhesive.
  101. 101.  In March 2012, a “All-Bond Universal” was discovered, which can be used in: i.total-etch, self-etch and selective etch techniques, ii.can be used with any dual-cure, self-cure and light-cure materials without the need of a separate activator, iii.can also be used for both direct and indirect substrates, and can bond with any dental substrates.  All-Bond Universal is the first truly “universal adhesive”.
  102. 102. IS FUTURABOND DC-THE EIGTH GENERATION BONDING AGENT?
  103. 103. BASED ON THE TREATMENT OF SMEAR LAYER SMEAR LAYER SMEAR LAYER SMEAR LAYER MODIFYING REMOVAL DISSOLVING
  104. 104. SMEAR LAYER  It was first suggested by Skinner in 1961.  Coined by Boyde in 1963.  0.5-2µm thick, granular  Smear plugs…1-10µm
  105. 105. WHY IS THE PRESENCE OF SMEAR LAYER DETRIMENTAL TO BONDING?  It is a weak attachment to dentin and is brittle  so it can be easily dislodged & prone to cohesive failure.  Therefore to overcome this, etch & rinse adhesive was developed.
  106. 106. SMEAR LAYER REMOVAL  DRAWBACK OF COMPLETE REMOVAL OF SMEAR LAYER: Increases dentin permeability and flow of the dentinal fluid Thus diluting the bonding agent  Examples:  IV & V generation dentin bonding agents.
  107. 107. SMEAR LAYER MODIFYING  Examples:  II & III generation dentin bonding agents.  Incorporation of smear layer inhibited proper bonding and resulted in loss of bond strength.
  108. 108. SMEAR LAYER DISSOLVING  Self-etching adhesives dissolve and include the smear layer in the hybridization process.  BASED ON Ph STRONG INTERMEDIARY MILD (<1) (1-2) (≅ 2)
  109. 109. Suresh Chandra et al.Comparative evaluation of self-etching primers sixth, fourth& fifth generation dentin bonding systems on carious and normal dentin.J Conser Dent2008;11(4):154-158  Study comparing bond strengths of total etch and self etch primer to carious affected and normal dentin.  Result- higher bond strength with normal dentin than caries affected dentin  Discussion: self etching primers needed highest mean shear load to fracture followed by V, IV generation bonding agents  Self etching primers superficially demineralize normal dentin by dissolving fibrils
  110. 110.  Thus aiding in monomer infiltration.  Later the dentin is not washed therefore shrinkage of collagen is avoided.  According to the study the bond strength of self etching primers > fourth & fifth .
  111. 111. BONDING EFFICACY OF VI AND VII GENERATION BONDING AGENTS  Manjula Nair, Joseph Paul et al. comparative evaluation of bonding efficacy of VI and VII generation dentin bonding agents: an invitro study. J Conserv Dent 2014; 17(1):27-30.  Aim: to compare shear bond strength of VIth and VII dentin bonding agents. Materials used VI DBA ADPER SEPLUS PH<1 XENO III PH-1.4 VII DBA ADPER EASY ONE PH-2.3 XENO V
  112. 112.  Result: VII>VI DBA  Discussion:  VI generation bonding agents have less bond strength to dentin due to high acidity resulting in higher amount of demineralization.  But the VII generation dentin bonding agents (mild self etch adhesives) demineralise upto one µm only keeping residual hydroxyapatite still attached to collagen.  This 1µm is enough for micromechanical retention .
  113. 113.  The retention of hydroxyapatite within the hybrid layer acts as receptor for chemical bonding.  Therefore this leads to higher bond strength with mild self etch adhesives.  So this is the cause for low bond strength with Adper SE Plus and Xeno III.  Though according to this study VII generation has higher adhesive property than VI, some studies contradict this.
  114. 114. Comparative evaluation of bonding efficacy of sixth,seventh and eighth generation bonding agents:an in vitro study. Paul Joseph et al.Int .Res. J Pharm.2013,4(9)  The aim of the study was to compare In-vitro the micro tensile bond strength of sixth generation (Clearfil SE Bond, Kuraray, Japan), seventh generation (Adper Easy One, 3 M ESPE, Germany) and eighth generation ((Futurabond DC, Voco, Germany) dentin bonding agents.  Results:  Futurabond DC, Voco, Germany>Clearfil SE Bond, Kuraray, Japan>Adper Easy One, 3 M ESPE, Germany)
  115. 115. Figure 3: Specimens obtained after hard tis sue microtome sectioning Figure 4: Universal Testing Machine
  116. 116. CLINICAL APPLICATION OF SELF-ETCH BONDING SYSTEMS  Class V composite resin restoration using a self-etch two step system a) Application of self-etch primer. b) Application of adhesive. c) Completed Class V composite resin restoration.
  117. 117.  ANTERIOR COMPOSITE RESTORATIONS(CLASS III,IV)
  118. 118.  POSTERIOR COMPOSITE RESIN RESTORATIONS  Core build up restoration with light cured composite resin using two-step self-etch bonding system. a) After removal of defective amalgam restoration b) Application of self-etching primer c) Application of adhesive d) Completed composite restoration in molars and the premolar
  119. 119.  RESTORATION OF PRIMARY TEETH  Self-etch adhesives are an alternative to total etch systems.  But ,the all in one adhesives should be used in combination with compomers(polyalkenoic acid modified composite resins) & only in small to medium sized cavities with adequate macroretention. (Quintessence International, vol(8),nov-dec2013)
  120. 120.  CORE BUILD-UP WITH LIGHT-CURED COMPOSITE RESIN:  CORE BUILD UP WITH FLOWABLE COMPOSITE….DEFECTIVE AMALGAM RESTORATION…..TWO STEP SEA….FULL CERAMIC PARTIAL CROWN
  121. 121. EXAMPLE OF A SELF-ETCH TWO STEP BONDING SYSTEM INCLUDING ACTIVATOR(ADHESE/ADHESE DC ACTIVATOR) FOR COMBINATION WITH DUAL-CURED RESIN CEMENTS & CORE BUILD-UP COMPOSITES
  122. 122. In the combined post & core technique,the same dual cured composite resin is used for adhesive post cementation & as core material. a. try in of FRC post. b. application of self-etch primer-adhesive into root canal using endo-microbrush. c.adhesively cemented FRC post with composite core build-up. a A.
  123. 123.  TREATMENT OF CERVICAL DENTIN HYPERSENSITIVITY  PREVENTION OF ROOT SURFACE CARIES  ADHESIVE CEMENTATION OF INDIRECT RESTORATION
  124. 124. MICROLEAKAGE  DEFINITION  It is the passage of bacteria and their toxins between restoration margins and tooth preparation walls  MECHANISM OF ACTION:  The presence of gaps at the resin-dentin interface leads to ingress of bacteria.
  125. 125.  Therefore bonding the resin to a preparation with cavosurface margins in enamel is the best way to prevent microleakage.  Bacteria are able to survive & proliferate within the fluid filled marginal gaps, thus leading to secondary caries.
  126. 126. NANOLEAKAGE  It is the small porosities in the hybrid layer or at the transition between the hybrid layer and the dentin that allow the passage of particles of silver nitrate dye.  Penetration of ammoniacal silver nitrate results in two patterns:  Spotted pattern-in the hybrid layer of self-etch adhesives due to incomplete resin infiltration.  Reticular pattern-that occurs in the adhesive layer due to incomplete removal of water from the bonding area.
  127. 127. NANOLEAKAGE UNDER ELECTRON MICROSCOPE. Spotted pattern in the hybrid layer formed by one-step self-etch adhesive Reticular pattern and water trees in adhesive layer formed by self etch adhesive
  128. 128. ANTIBACTERIAL PROPERTY OF DENTIN BONDING AGENTS  The development of adhesive systems have enabled variable cavity designs to preserve tooth structure and treatment of dental caries has shifted from the traditional method to that with downsized cavities.  Inspite of considerable improvement in the recent years , polymerization shrinkage & the resultant contraction gaps in tooth restoration interface continue to be a significant problem associated with composite resin restorations.
  129. 129.  Thus cariogenic bacteria like Streptococcus mutans,Lactobacillus acidophilus,Lactobacillus casei and Streptococcus salivarius can invade along the microgaps and lead to secondary caries.  Therefore it is imperial to provide resin based materials with antibacterial activity.  Imazato et al have reported the antibacterial property of MDPB ((methacryloyldodecylpyridinium bromide) which is monomer present in the bonding agent.  Also, acidic monomers like 10-MDP(10-methacryloyloxy decyl dihydrogen phosphate) due to its inherent acidity has antibacterial property.
  130. 130. Amin S,Shetty HK,Varma RK,Amin V,Nair PM.Comparative evaluation of antibacterial activity of total etch and self etch adhesive systems:An ex vitro study.J Conser Dent 2014 ;17:266-70  The purpose of the study was to compare the antibacterial activity of total- etch and self-etch adhesive systems against Sreptococcus mutans , Lactobacillus acidophilus , and Actinomyces viscosus through disk diffusion method .Of all the materials tested, the antibacterial effects may be related to the acidic nature of the adhesive systems. 
  131. 131. Sampath PB, Hegde MN, Hegde P.Assessment of the antibacterial properties of newer dentin bonding agents. An in vitro study.Contemp Clin Dent 2011;2:165-9.  The aim of this study was to evaluate and compare the antibacterial activity on Streptococcus mutans using direct control test.The incorporation of antibacterial agents into dentin bonding agents may become an essential factor in inhibiting residual bacteria in the cavity.
  132. 132. Amin S,Shetty, HK,Varma et al. Comparative evaluation of antibacterial activity of total etch and self etch adhesive systems:An ex vitro study.J Conser Dent 2014 ;17:266-70  Aim: The aim of this ex vivo study was to compare the antibacterial activity of total-etch and self- etch adhesive systems against Streptococcus mutans, Lactobacillus acidophilus, and Actinomyces viscosus through disk diffusion method.  Materials and Methods: The antibacterial effects of Single Bond (SB) and Adper Prompt (AP) and aqueous solution of chlorhexidine 0.2% (positive control) were tested against standard strain of S. mutans, L. acidophilus, and A. viscosus using the disk diffusion method. The diameters of inhibition zones were measured in millimeters. Data was analyzed using Kruskal-Wallis test. Mann-Whitney U test was used for pairwise comparison.
  133. 133.  Result: Of all the materials tested, AP(Adper Prompt) showed the maximum inhibitory action against S. mutans and L. acidophilus. Aqueous solution of chlorhexidine 0.2% showed the maximum inhibitory action against A. viscosus. Very minimal antibacterial effect was noted for SB(Single Bond).  Conclusion: The antibacterial effects observed for the tested different dentin bonding systems may be related to the acidic nature of the materials.
  134. 134. BIOCOMPATIBILITY  Biological testing of DBA is a delicate and complex process.  Unlike most dental materials, many dentin bonding systems are made up of more than one material e.g. cleanser , primer , bonding resin etc.
  135. 135. • A very limited number of reports have been published on the biocompatibility of the first generation. Which may be due to their inferior physical properties. • Van Leeuwen et al showed no severe reactions even in extremely deep caries in their study. 1st generation. • Most studies are carried out using Scotch Bond. • It might have a adverse effect on pulp tissue when placed in contact with vital tooth and proper pulpal protection was recommended. 2nd generation. • Tests showed that the bonding material as well as the individual components were toxic. 3rd generation.
  136. 136. International endodontic journal. Volume 44 number 9 september 2011.
  137. 137. *Aim * To evaluate the genotoxicity of four different adhesives, Clearfil SE Bond,SL Bond, i Bond and Clearfil Protect Bond and the primers of Clearfil SE Bond and Clearfil Protect Bond. *Results * A significant increase (*P* < 0.001) compared to untreated controls in DNA damage was observed with 'Clearfil Protect Bond' and 'Clearfil SE Bond' primer in human lymphocytes at concentrations of 2.5 and 5.0 mg mL-1. Clearfil Protect Bond and Clearfil SE Bond adhesives induced significant (*P* < 0.001) DNA damage only at the higher concentration of 5.0 mg mL-1. No significant increase in DNA damage was observed with SL Bond and i Bond. Nosignificant DNA damage was observed with any dentine bonding agents at the lower concentration of 1.25 mg mL-1. *Conclusions * 'Clearfil Protect Bond' and 'Clearfil SE Bond' primers/adhesives increased DNA damage in human peripheral lymphocytes in high doses.
  138. 138. CLINICAL FACTORS AFFECTING ADHESION  Flow of saliva and/or blood contamination  Moisture contamination from handpiece or air water syringe  Oil contamination of handpieces or air-water syringes  Fluoride content of teeth  Location and size of dentinal tubules  Presence of plaque,calculus,extrinsic stains or debris  Presence of bases or liners on prepared teeth  Tooth dehydration  Presence of residual intermediary cements
  139. 139. BONDING TO AMALGAM  Bonding of amalgam restoration to tooth is still a debatable topic.  The use of adhesive systems beneath amalgam restoration reduces or prevents microleakage, makes cavosurface angle less susceptible to demineralization when compared to varnish.  There is reduction in sensitivity and more conservative cavity preparation can be achieved when amalgam is bonded to tooth.
  140. 140.  Staninec M (1989) showed that retention with amalgam bonding is equal to or superior to traditional means of mechanical retention.  Tig IA, Fodor O, Moldovan M et al (2005) noticed that at higher magnification, teeth restored with unbonded amalgam had more spaces and artifacts at the amalgam-tooth structure interface when compared with those
  141. 141. Failures can occur at various levels:  between mineralised and demineralised dentin  between demineralised dentin and bonding agent  within layer of bonding agent  between bonding agent and composite resin. Affected by –  dentin wetness  tooth flexure  arch  size of lesion  substrate  material factors
  142. 142. CONCLUSION In today’s era, numerous improvements in materials and procedures have been made to meet the growing aesthetic demands of the patients.  In all the aesthetic restorations a bonding step is involved to ensure durability and reliability.
  143. 143.  Thus the ideal bonding system should be biocompatible, bond perfectly to enamel and dentin, have sufficient strength to resist to failure as a result of masticatory forces, have mechanical properties close to those of tooth, and be resistant to degradation in oral environment and easy to use.
  144. 144. BIBLIOGRAPHY  STURDEVANT'S ART & SCIENCE OF DENTISTRY-4TH, 5TH & 6TH EDITION  PHILLIPS-SCIENCE OF DENTAL MATERIALS...11TH EDITION  TOOTH COLORED RESTORATIVES-PRINCIPLES AND TECHNIQUES..9TH EDITION  PICKARD'S MANUAL OF OPERATIVE DENTISTRY...8TH EDITION  TEXTBOOK OF OPERATIVE DENTISTRY-SUMEETHA SANDHU..1ST EDITION  MATERIALS USED IN DENTISTRY….S.MAHALAXMI
  145. 145.  M.Bourbia, D.Ma, D.G Cvitkovitch et al.Cariogenic bacteria degrade dental resin composite and adhesives.J Dent Res 92(11):989-994,2013.  Bernd Haller et al.Quintessence International,1,nov-dec2013.  .Arora R, Rao MH. Comparative evaluation of antibacterial effects of four dentin bonding systems: An in vitro study.J Conserv Dent 2013;16:466- 70  2.Taha MY, Al-Shakir NM, Al-Sabawi NA. Antibacterial effect of Dentin  Bonding Agents:An in vitro study. Al-Rafidain Dent J. 2012;12(2):228- 234.  4.Hegde MN,Hegde P,Shetty V,Sampath P B.Assessment of antibacterial activity of self-etching dental adhesive systems:An in vitro study .J Conserv Dent 2008;11:150-3

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