DENTIN BONDING AGENTS

Presented by: Anuradha RoyCollected by- Aziz IkbalFinal year BDSDept. Of Conservative and Endodontics

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 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 SUMMARY BIBLIOGRAPHY

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.

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.

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:

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.

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.

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 pattern with poorer definition.

<27% - Formation of dicalcium phosphate dihydrate - cannot

be easily removed by rinsing.

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.

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

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.)

Adhesion to laser-ablated or laser-etched dentin and enamel was inferior to that of conventional rotary preparation and acid etching.

( Dental Materials (2005) )

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.

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

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

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.

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 .

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.

Therefore optimal bonding can occur by:

1.Removal of smear layer by using etch and rinse adhesives.

2.Incorporation of smear layer into bonding layer by

self-etch adhesives

Complete removal of smearlayer increases the dentin permeability by 90%.

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.

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.

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: 1. 37% phoshporic acid 2. nitric acid 3. citric acid 4. EDTA (ethylene diamine tetra-acetic acid)

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.

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)

Acid washing / rinsingRemoves smear layerDissolves HA

Drying shrinks remainingCollagen polymer molecules

Rehydration / primingSwells collagen

Mechanism of dentine bonding

Monomer penetration

Mechanism of dentine bonding

Monomer polymerisationAnd collagen entanglement

CLASSIFICATION1. HISTORICAL STRATEGIES

FIRST GENERATION(1965) SECOND GENERATION(1978) THIRD GENERATION(1984)

2.CURRENT STRATEGIES ETCH & RINSE ADESIVESi. 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 ADHESIVEo ONE STEP –TWO COMPONENT - SELF ETCH ADHESIVE SINGLE COMPONENT-ONE STEP-SELF ETCH ADHESIVE(SEVENTH

GENERATION)

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

( SIXTH GENERATION ) ( SEVENTH GENERATION)

TWO STEP-TWO COMPONENT –SELF ETCH ADHESIVEONE STEP –TWO COMPONENT - SELF ETCH ADHESIVE

BASED ON MODERN ADHESION STRATEGY: Van Meerbek et al(2001) suggested a classification based on adhesion strategy.

TYPE OF ADHESIVE STEPS INVOLVED

ETCH AND RINSE ADHESIVES

THREE STEP ADHESIVE:FOURTH GENERATION

TWO STEP ADHESIVE:FIFTH GENERATION

SELF ETCH ADHESIVESTWO STEP ADHESIVE:SIXTH GENERATION

ONE STEP ADHESIVE:SEVENTH GENERATION

BASED ON THE TREATMENT OF SMEAR LAYER:

Smear layer modifying

Smear layer removal

Smear layer dissolving

DECADE BONDING AGENT FEATURES

1960s 1970s

FIRST GENERATIONSECOND 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

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).

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.

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).

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

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

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)

Clinical result:

It had poor bond strength of 2-3MPa. Therefore when used to restore noncarious cervical

lesions without mechanical retention.

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.

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.

EXAMPLES:

Clearfil Bond System(Kuraray,Japan) Scotchbond(3M ESPE) Bondlite(Kerr Corporation.CA) Prisma Universal Bond(Dentsply)

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

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)

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

TenureOxalate 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.

CURRENT STRATEGIES FOR RESIN-DENTIN BONDING1. 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.

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.

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 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

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.

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

• BRAND NAMES-

• All Bond 2 & All Bond 3• Optibond FL(Kerr Corporation)• Adper Scotchbond Multi-

purpose(3M ESPE)

• BOND STRENGTH-• 17-30 Mpa.

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 .

IV GENERATION DENTIN BONDING AGENT:

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

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.

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.

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

It consists of

BOTTLE I BOTTLE II (Etchant+Primer) (Adhesive)

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

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.

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 practice.

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

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

VI GENERATION BONDING AGENT1. 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.

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)

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)

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.

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.

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.

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).

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.

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+

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.

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.

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”.

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.

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.

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

BIBLIOGRAPHY