LinkedIn emplea cookies para mejorar la funcionalidad y el rendimiento de nuestro sitio web, así como para ofrecer publicidad relevante. Si continúas navegando por ese sitio web, aceptas el uso de cookies. Consulta nuestras Condiciones de uso y nuestra Política de privacidad para más información.
LinkedIn emplea cookies para mejorar la funcionalidad y el rendimiento de nuestro sitio web, así como para ofrecer publicidad relevante. Si continúas navegando por ese sitio web, aceptas el uso de cookies. Consulta nuestra Política de privacidad y nuestras Condiciones de uso para más información.
By Sneha Ratnani
Mds part 1
Principles of adhesion
Indications for Use of Adhesives
Advantages of Bonding Techniques
Mechanisms of adhesion
Factors affecting adhesion
Challenges in adhesion
Dentin bonding systems
Evolution of bonding agents
Classification of bonding agents
The dental profession has spent most of its history restoring the effects of dental disease, but
currently, the majority of restoration work is replacement or repair of prior treatment.
One reason for the change is population’s burgeoning interest in health and beauty, which
is driving increased demand for cosmetic dental procedures.
Historically, for many adults, the achievement of a pretty smile has meant submission to
extensive invasive procedures and high-cost fixed prosthodontics.
Improvements in tooth-colored restoratives and bonding technology have made cosmetic
dental procedures more palatable and feasible.
In addition, newer technology allows the general practitioner to handle many previously
complex esthetic problems more simply, conservatively, and economically.
The fundamental objective of all restorations since centuries has been to create adhesion between two
dissimilar surfaces: mineralized tooth structure and the restorative materials.
The invention of dentin bonding agent is like a - dream come true for dentistry, which led to the
beginning of new era of adhesive dentistry.
The concept of dentistry with the introduction of adhesives has changed from - Extension for
Prevention to PREVENTION OF EXTENSION !!!
Theprinciplesof adhesivedentistrydatesbackto 1955
phosphoricacidto improveadhesionof paintsandresin
coatingsto metalsurfaces, appliedacidto theteethto
The traditional “drilland fill”approachis
fading now because of numerous
advancements taking place in restorative
The state in which two surfaces are held together by interfacial forces, which may consists of
valence forces or interlocking forces or both.
(The American Society for Testing and Materials; specification D 907)
Adherend: The surface or substrate that is adhered
Adhesive/adherent: A material that can join substances together, resist separation and transmit loads
across the bond
Adhesive failure: The bond that fails at the interface between the two substrates.
Cohesive failure: The bond fails within one of the substrates, but not at the interface.
Adherend 1 Adherend 2
or Luting Cement
Interface 2Interface 1
ENAMEL, DENTIN >
Liner, Base, Cement >
Post and Core >
Dental Amalgam >
< Composite, Amalgam
< Cast Inlay, Onlay, or Crown
< All-Ceramic Inlay, Onlay, or Crown
< Veneers, Maryland Bridges
< Orthodontic Brackets
Diagrammaticrepresentation of dental adhesive system, where Adherend 1 is
enamel, dentinor both.
Adhesive is bondingagent,
Adherend 2 is compositeresin
Adhesive restorative techniques are currently used to accomplish the following:
1. Restore Class I, II, III, IV, V, and VI carious or traumatic defects
2. Change the shape and the color of anterior teeth
3. Improve retention for metallic crowns or for porcelain-fused-to-metal crowns
4. Bond all-ceramic restorations
5. Bond indirect resin-based restorations
6. Seal pits and fissures
7. Bond orthodontic brackets
8. Bond periodontal splints and conservative tooth replacement prostheses
9. Repair existing restorations (composite, amalgam, ceramic, or ceramometal)
10. Provide foundations for crowns
11. Desensitize exposed root surfaces
12. Seal beneath or bond amalgam restorations to tooth structure
13. Impregnate dentin that has been exposed to the oral fluids, making it less susceptible to caries
14. Bond fractured fragments of anterior teeth
15. Bond prefabricated and cast posts
16. Reinforce fragile roots internally
17. Seal apical restorations placed during endodontic surgery
Four different mechanisms of adhesion has been described:
Mechanical adhesion – interlocking of the adhesive with irregularities in the surface of the substrate,
Adsorption adhesion – chemical bonding between the adhesive and the adherend.
The forces involved may be primary (ionic or covalent) or secondary (hydrogen bonds, dipole
interaction or van der Waals) valence forces.
Diffusion adhesion – interlocking between the mobile molecules, such as adhesion of two polymers
through diffusion of polymer chain ends across an interface.
Electrostatic adhesion – an electric double layer at the interface of a metal with a polymer that is part
of the total bonding mechanism.
Wetting is the ability of the liquid to flow easily over the entire surface and adhere to the
If the adhesive does not wet the surface of the adherend, adhesion between the adhesive and
adherend will be negligible or nonexistent.
Wetting is principally influenced by:
– Cleanliness of the adherend : Cleaner surface, greater adhesion.
– Surface energy of the adherend: More surface energy, greater adhesion
The extent to which an adhesive wets the surface of the adherend may be
determined by measuring the contact angle, which is the angle, formed by the
adhesive with the adherend at their interface.
The stronger the attraction of the adhesive for the adherend, the smaller will be
the contact angle.
The zero contact angle is the best to obtain wetting
◦ The surface tension of the liquid and the surface energy of the adherend,
ultimately determine the degree of wetting that occurs.
◦ Generally, the harder the surface , the higher the surface energy will be, which
means that adhesive properties of the material will be higher.
◦ The substrate surface should be clean as contamination prevents the adhesion.
◦ Adhesive should be able to fill their regularities making the surface smooth
allowing proper or intimate contact
◦ The higher the water content, the poorer is the adhesion.
◦ Water canreact withbothmaterialsby the high polargroupandhydrogenbond
whichcan hamper the adhesion
Steps in Forming Good Adhesion
(1) Clean adherend
(2) Good wetting
(3) Intimate adaptation
(5) Good curing
• To bond to enamel, it is very important to focus on the mineral component (hydroxyapatite)
• Buonocore, 1955
– was the first to reveal the adhesion of acrylic resin to acid etched enamel.
– used 85 percent phosphoric acid for etching
• Silverstone revealed that the optimum concentration of phosphoric acid should range
between 30 to 40 percent to get a satisfactory adhesion to the enamel.
If the concentration is greater than 50 percent
◦ Monocalcium phosphate monohydrate may get precipitated
Concentrations lower than 30 percent,
◦ Dicalcium phosphate monohydrate is precipitated which interferes with
Percentage of etchants used:
◦ %35 to 40%
Use of lower concentrations of phosphoric acid and reduced etching time has
shown to give an adequate etch of the enamel while avoiding excessive
demineralization of the dentin
Acid application time: ideally 10 seconds
◦ studies show that enamel should not be etched for more than 15 to 20 seconds
Scanning electron micrograph of enamel etched with 35% phosphoric acid (3M ESPE, St. Paul, Minn) for 15 seconds.
Enamel acid etching – removes 10 micron of enamel
Creates microporous layer 5 to50 microns deep
Smooth surface – irregular surface with high surface energy 72dynes/cm
Unfilled liquid acrylic resin (enamel bonding agent)
Wets the surface
Enters into microporosities by capillary action
Two types of resin tags are formed
(form between enamel prisms peripheries ) (form at the core of enamel prisms )
Removes residual pellicle exposure to the inorganic crystallite component of enamel.
Creates a porous layer with the depth of the pores ranging from 5-10 µm.
Increases as the wettublity and surface area of the enamel substrate.
Raises the surface energy of enamel with creation of reactive polar sites.
Silverstone et al (1975) studied the morphological changes in SEM produced on the acid
etched enamel surface.
Exposure of human enamel to conditioning solutions produces 3 basic etching patterns.
Type I: (Preferential prism center etching)
Dissolution of prism cores without dissolution of prism
peripheries resulting in a honey comb appearance. The average
diameter of the hollowed prism core is measured as about 3µm.
This is the most commonest type of etching pattern.
Type II: Dissolution of peripheral enamel without dissolution of
prism cores resulting in a cobblestone appearance
Type III : Mixed pattern. Etching pattern is less distinct and
includes areas resembling type I and type II patterns as well as
regions in which the etching pattern appears unrelated to prism
morphology.This type of etching in general is associated with the
presence of prism less enamel and appears as a generalized
Clinically a uniform dull appearance is an indication that the tooth surface has been
Silverstone in 1974 showed that etched enamel surface under polarized light resulted in 3
1. Etched Zone
2. Qualitative Zone
3. Quantitative Zone
1. Etched Zone
This is the narrow zone of enamel at about 10µm in depth, that is removed by etching. The fully
reacted mineral crystals are removed resulting in the exposure of more reactive surface. This increased
surface area and a reduced surface tension allows resin to wet in the etched surface more readily.
2. Qualitative Zone:
This zone is about 20µm in depth and it is rendered porous during acid etching of the enamel when
identified qualitatively using polarized light.
3. Quantitative Zone:
This third zone is almost up to 20µm depth. It is qualitatively indistinguishable from adjacent enamel
and can be detected with quantitative polarized light. In human enamel, the pores may be spherical,
elongated or sometimes as large chamber that are connected to smaller channels called ink bottle
Clean and wash the teeth with water.
Isolate to prevent any contamination from
saliva or gingival crevicular fluid
Apply acid etchant in the form of liquid or gel
for10 to 15 seconds.
Deciduous teeth require longer time for
etching than permanent teeth because of the
presence of aprismatic enamel in deciduous
• Now apply bonding agent and low viscosity monomers over the etched enamel
• Generally, enamel bonding agents contain Bis-GMA or UDMA with TEGDMA
added to lower the viscosity of the bonding agent.
• The bonding agents due to their low viscosity, rapidly wet and penetrate the
clean, dried, conditioned enamel into the microspaces forming resin tags.
Fluorosed teeth have an altered structure, composition and appearance.
With the increase in severity of fluorosis enamel becomes more porous and sub-surface
lesion extends towards the inner enamel.
Several studies have shown that composites can be bonded successfully to fluorosed enamel
depending on the degree of fluorosis.
It is always recommended to grind the enamel before bonding as it is seen that bond
strength of composites to ground enamel of teeth with moderate fluorosis is similar to that
of normal teeth.
Acid etching is good for enamel bonding but not for dentin bonding in fluorosed teeth. As a
consequence a good choice of adhesive, it would be a two-step self etch adhesive with an
additional acid etching step for the enamel.
Adhesion of restorative materials to enamel has become a routine and reliable aspect
of modern restorative dentistry,
But adhesion to dentin has proved to be more difficult and less predictable.
Much of the difficulty in bonding to dentin is the result of the complex microstructure
and variable composition of dentin in different areas of the tooth.
Thus, the composition of dentin is much different than that of enamel, and one would
expect it to behave differently when etched with acid.
The presence of water and organic components lower the surface energy of dentin and
make bonding with hydrophobic resins essentially impossible.
Dentin also contains a dense network of tubules
that connect the pulp with the dentinoenamel
junction (DEJ) .
A cuff of hypermineralized dentin called
peritubular dentin lines the tubules.
The less mineralized intertubular dentin contains
collagen fibrils with the characteristic collagen
The intertubular dentin is penetrated by
submicron channels, which allow the passage of
tubular liquid and fibers between neighboring
tubules, forming intertubular anastomoses
Dentin is an intrinsically hydrated tissue, penetrated by a
maze of 1- to 0.25-μm-diameter fluid-filled dentin
Movement of fluid from the pulp to the DEJ is a result of
a slight but constant pulpal pressure
Pulpal pressure has a magnitude of 25 to 30 mm Hg or
34 to 40 cm H2O.
Dentinal tubules enclose cellular extensions from the
odontoblasts and are in direct communication with the
Inside the tubule lumen, other fibrous organic
structures are present, such as the lamina limitans, which
substantially decreases the functional radius of the
Relative number of dentin tubules and tubule volume at
different dentin levels as measured at different distances
from the dentinoenamel Junction. Adapted from Heymann
Distribution of tubules in dentin
Dentin close to the pulp shows a
higher tubule density than in
dentin remote from the pulp.
The higher the tubule density,
the lower the bond strength
values of the dentin adhesives to
The relative area occupied by dentin tubules decreases with increasing distance from the
Created whenever dentin is cut or ground with hand or rotary dental instruments and is about 1 to 5
μm thick (Brannstrom, 1982).
It consists of debris that presumably reflects the composition of the underlying dentin.
Thus, the composition of superficial versus deep smear layers would be expected to be quite different.
It has a uniform, amorphous structure, which appears to completely occlude the orifices of all dentinal
Smear plugs are projections of the smear layer that extend to variable distances into dentinal tubules
when the smear layer is created
The smear layer has both advantages and disadvantages in the bonding process (Yap et al,
Advantages include :
Reduction of dentin permeability to toxins and oral fluids;
Reduction of diffusion (usually inwards) and convection of fluids (outwards by hydrostatic
pressure or inwards, for example, while restorations are cemented),
Reduction of wetness of cut dentin surfaces, and
Prevention of bacterial penetration of dentinal tubules.
Wetness and the harboring of bacteria or their products,
It reduces the surface energy which compromises surface wetting,
Prevents the intimate surface contact between the adhesive and dentin substrate, and
Prevents resin penetration into dentinal tubules (Gwinnett, 1984; Rees and Jacobsen, 1990).
It acts like a separating agent since it is an intrinsically weak structure (5 to 6 MPa cohesive
strength) that bond weakly to the underlying dentin (Tao and Pashley, 1988).
Further, the mineral component of the smear layer may dissolve slowly under a leaking
restoration or may be removed by acid produced by bacteria to leave a gap which in turn
increases marginal leakage and possibly secondary caries.
Factors such as :
radius and length of the tubules,
the viscosity of dentin fluid,
the pressure gradient,
the molecular size of the substances dissolved in the tubular fluid, and
the rate of removal of substances by the blood vessels in the pulp affect
All of these variables make dentin a dynamic substrate and consequently a difficult
substrate for bonding.
The factors important in understanding the over all ‘bonding equation’ is
Quality of dentin
Higher bond strength is achieved for younger teeth compared to the dentin of
Altered dentin (sclertic or carious).
Variation in density of the tubules.
Location of dentin (whether peripheral or close to pulp)
Etching of dentin (too long etching results in impeded hybrid layer formation and
produces a weaker bond strength.
The dentin should not be desiccated; it must be kept moist during the entire
procedure. If it dries up, the collagen structure collapses.
The tooth factors include
Lesion size and shape
Enamel and dentin structure
Patient factors associated with dentin adhesion are:
•The degree of occlusal stress
Saliva and/or blood contamination
Moisture contamination from handpieces or air-water syringes
Oil contamination from handpieces or air-water syringes
Surface roughness of tooth surface
Mechanical undercuts in tooth preparation
Fluoride content of teeth
Presence of plaque, calculus, extrinsic stains or debris
Presence of bases and liners on the prepared teeth
Conditioner (Cleanser, Etchant)
Conditioner is usually a weak organic acid (e.g. maleic acid), a low concentration of a
stronger inorganic acid (e.g. phosphoric or nitric acid), or a chelating agent (e.g.
Heavily alters or removes the smear layer
Demineralizes peritubular and intertubular surface dentin and, thereby, exposes
Demineralizes up to a depth of 7.5 microns
Depth of demineralization depends on type of acid, its concentration, and etching
More mineralized peritubular dentin is etched more deeply than the intertubular
Increases dentin permeability by 4 to 9 times.
Primer is usually a bifunctional monomer in a volatile solvent such as acetone or
alcohol; a bifunctional monomer is one that has a hydrophilic end (i.e., one with an
affinity for water) and a hydrophobic end (one lacking an affinity for water);
Examples of bifunctional monomers include
HEMA (hydroxyethyl methacrylate),
NMSA (N-methacryloyl-5- aminosalicylic acid),
PMDM (pyromellitic diethylmethacrylate), and
4-META (4- methacryloxyethyl trimellitate anhydride).
Links the hydrophilic dentin to the hydrophobic adhesive resin; is able to do this
because of its bifunctional nature (i.e., primer's hydrophilic end bonds to the wet
dentin and its hydrophobic end bonds to the adhesive resin)
Promotes infiltration of demineralized peritubular and intertubular dentin by its
own monomers and those of the adhesive resin.
Increases wettability of the conditioned dentin surface and increases contact
between the dentin and resin
Adhesive 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.
Combines with the primer’s monomers to form a resin-reinforced
hybrid layer (resin-dentin interdiffusion zone) from 1 to 5 microns
Forms resin tags to seal the dentin tubules provides methacrylate
groups to bond with the subsequently placed resin composite
One of the first products that used this method for enamel and dentin treatment
was Scotchbond Multi-Purpose Adhesive, which used 10% to 12% maleic acid.
Scotchbond MPA and most other current-generation products now use the same
acid for etching dentin that they use for etching enamel (i.e., concentrations of
phosphoric acid that range from 32 to 40%).
This method of etching dentin with a 32 to 40% concentration of phosphoric acid
is called the total-etch technique and was first discussed by Fusayama in 1977.
Mechanism of dentine bonding
And collagen entanglement
Ideally a dentin bonding agent should have both hydrophilic and hydrophobic
ends. The hydrophilic end displaces the dentinal fluid, to wet the surface. The
hydrophobic end bonds to the composite resin.
• Mechanism of Bonding
M R X
• Where, M is the double bond of methacrylate which copolymerizes with
• R is the spacer which makes the molecule large.
• X is a functional group for bonding which bonds to inorganic or organic portion
Bonding to the inorganic part of dentin involves ionic interaction among the
negatively charged group on X
◦ for example, phosphates, amino acids and amino alcohols, or dicarboxylates)
and the positively charged calcium ions.
Commonly used bonding systems employ use of phosphates.
• Bonding to the organic part of dentin
– Interaction with
• Amino (–NH),
• Hydroxyl (–OH),
• Carboxylate (–COOH),
• Amide (–CONH) groups
• Dentin bonding agents have
– carboxylic acid
– anhydrides and
– carboxylic acid chlorides
which extract hydrogen from
the above mentioned groups
and bond chemically.
present in dentinal
Developed in 1960s
Relied on adhesion to smear layer
No. of steps involved were two; etching of enamel +
application of adhesive
Did not recommend dentin etch
Bowen formulated Cervident containing N-
phenylglycine glycidyl methacrylate (NPG-GMA).
NPG-GMA is a surface-active comonomer that
theoretically could mediate water- resistant chemical
bonds of resin to dentinal calcium.
This means that one end of this molecule bonds to dentin while the other polymerizes with
bond strengths - 2 to 3 MPa .
The clinical results with these systems were poor .
No improvement in marginal leakage when compared to conventional unfilled enamel bonding
resins (Barkmeier and Cooley, 1991).
Based on Carbon-13 NMR analysis, it appears that no ionic bonding actually develops between
NPG-GMA and hydroxyapatite. (Jorge Perdigao, Edward Swift).
In the late 1970s the second-generation systems were introduced ,
Incorporated halophosphorus esters of unfilled resins such as bisphenol-A glycidyl
methacrylate (Bis-GMA), or hydroxyethyl methacrylate (HEMA), which substituted
Mechanism by which they bond to dentin was postulated to be through an ionic bond to
calcium by chlorophosphate groups.
The clinical performance of these bonding agents was relatively poor,
Shear dentinal bond strengths of only 2 to 6 MPa were reported
A major reason for the poor performance of these bonding agents is the fact that they bond to the
smear layer rather than to the underlying dentin hence,
Their bond strength is limited by the cohesive strength of the smear layer or the adhesion of the smear
layer to the dentin below (Tao et al, 1988).
These bond strengths were not great enough to counteract contraction stress generated by shrinking
composites, which is estimated to exceed 20 MPa in some cavities.
Furthermore, some studies indicate that bonds between phosphate esters and dentin may also be
hydrolyzed by immersion in water.
Therefore, composite resin tends to separate from dentin, forming gaps at restoration margins and
increasing the microleakage at margins in dentin or cementum
In third generation the smear layer was partially removed or modified rather than complete removal.
In most of the systems, the phosphate primer modifies the smear layer by softening it; after penetration,
it cures, forming a hard surface.
The adhesive is then applied, attaching the cured primer to the composite resin.
Bonding to smear layer-covered dentin was not very successful before 1990, however, because the
resins did not penetrate through the smear layer, bond was weak approached 10-12 MPa (Leinfelder,
The basis of third generation systems was laid in 1979 when the Japanese philosophy of acid-etching
the dentin to remove the smear layer gained acceptance.
The acid opens dentinal tubules partially and increases their permeability to form micromechanical
Based on this total-etch concept Clearfil New bond was introduced in 1984, which contains HEMA and
10-methacryloyoxy-decyl-dihydrogen phosphate (10-MDP), which had long hydrophobic and short
hydrophilic components as active components.
Leaving free minerals
-Total drying of surface
2nd step :
Adding adhesive resin
,Then adding Composite
Fourth-generation dentin adhesives were introduced for use on acid etched dentin.
Because the clinical technique involves simultaneous application of an acid to enamel and
dentin, this method is commonly known as the total-etch technique.
Also called the etch and rinse technique, it was the most common strategy for dentin bonding
during the 1990s and remains popular today.
Application of acid results in partial or total removal of smear layer and demineralization of
underlying dentine up to depth of 7.5 microns
Application of acid to dentin partial or total removal of the smear layer and demineralization of
intertubular and peritubular dentin,
open dentin tubules, and exposed collagen fibers, increased microporosity of the intertubular dentin
Dentin is demineralized by up to 7.5 μm depending on the type of acid, application time, and
The primer in a three-step system is designed to increase the critical surface tension of dentin.
When primer and bonding resins are applied to etched dentin, they penetrate the intertubular dentin,
forming a resin-dentin interdiffusion zone, or hybrid layer.
They also penetrate and polymerize in the open dentinal tubules, forming resin tags
In the three-bottle total etch bonding technique, acid is used to remove the smear layer and smear plugs from the dentin
and to remove peritubular dentin, increasing the diameter of the tubules thereby (Fig. A) that will form stronger resin tags.
The etched surface is then primed with dilute methacrylates (red) in a volatile solvent (Fig. B) to insure that the matrix is
expanded and precoated with methacrylates. Then a solvent-free adhesive (green) is applied that diffuses into the primed
surface and down into the tubules where it polymerizes with the primer (Fig. C).
Fourth-generation adhesives such as All-Bond 2,
OptiBond FL and Scotchbond Multipurpose are
basically composed of
An acid etching gel that is rinsed off;
A solution of primers that are reactive
hydrophilic monomers in ethanol, acetone,
An unfilled or filled fluid boding agent-
hydrophobic monomer such as Bis-GMA
combined with hydrophilic HEMA.
All-Bond 2 and Scotchbond Multipurpose are two of the
first fourth-generation adhesive systems, which rely on the
hydration of dentin as a critical parameter for effective
All-Bond 2 uses a phosphoric acid enamel/dentin
conditioning step to be followed by the application of
hydrophilic primers containing N-tolyglycine-glycidyl
methacrylate (NTG-GMA) and biphenyl methacrylate
(BPDM) in acetone.
This priming layer is followed by an unfilled resin
containing Bis-GMA and HEMA.
The original Scotchbond Multipurpose conditioned dentin
with 10% maleic acid solution followed by a primer
consisting of an aqueous layer of HEMA and Vitrebond
The adhesive resin system is also a Bis-GMA resin
containing HEMA. Later, maleic acid was replaced by
phosphoric acid to generate more consistent results.
Other fourth-generation adhesive systems include
Imperiva Bond (acid treatment – primer containing HEMA & 4-acryloxyethyltrimeric acid -
Triethylene glycol dimethacrylate (TEGDMA), dimethylamino ethylmethacrylate and butylated
Permaquik (acid conditioning- ethanol based primer (naturally occurring elastic resin+
Canada balsam+HEMA)- adhesive resin (Bis-GMA+glass filler).
Optibond and Solidbond employs partially filled adhesive resins, use of fillers in the adhesive
resin exhibits less shrinkage in the bonding layer
It is hypothesized that generating less residual shrinkage stress in the adhesive reduces bond
ProBOND is unique in that it does not require dentin conditioning.
It consists of an acetone/ethanol primer with a phosphate adhesion promoter,
PENTA and an adhesive containing a urethane dimethacrylate resin (UDMA),
PENTA and glutaraldehyde.
Liner Bond 2 introduced the concept of a no-rinse self-etching primer.
The primer consisted of pheny-P, HEMA, and N-methacryloyl 5-aminosalicyclic
acid (5-NMSA) and
a bonding resin containing 10-methacryloyldecyl dihydrogen phosphate (MDP),
Bis-GMA and colloidal silica
An additional feature of fourth-generation systems is the claim for their utility in multipurpose
In addition to dentin and enamel adhesion, bond strength claims were made for cast alloys, amalgam
Mean shear bond strength of the fourth-generation systems are reported to range from 17MPa to great
If the clinician carefully adhered to the specific recommendations made regarding the methods and
times required for application of the bonding agent, the results were highly effective.
Shear bond strengths to both enamel and dentin routinely approximated 25 MPa.
Such a process has permitted forms of esthetic and functional treatment not previously conceived.
-Total etching(removal of
Leaving free minerals on
-Without drying of surface
(residual water left)
2nd step :
Adding adhesive resin &
Eg: OptiBond Solo (and later OptiBond Solo Plus),
All- bond 2 and One-Step (BISCO)
Scotchbond MP and ScotchBond 1
These also are called the “one bottle” systems because they combine the primer and bonding agent into
a single solution.
A separate etching step still is required.
.The first of these products was LD Caulk’s Prime & Bond. When originally introduced, it was to be used
only when placing direct composite resin restorations.
Recently, it underwent two changes and has been renamed Prime & Bond 2.1.
The changes were addition of fluoride and inclusion of an elastomeric monomer to reduce the DBA‘s
Other fifth-generation products include OptiBond Solo
(SDS/Kerr), Single Bond (3M ESPE), PQ1 (Ultradent), and Gluma
One Bond (Heraeus Kulzer).
In general, these products have limitations.
Many require at least as much time to apply or even more time
than three-component products and they lack many of the
components necessary to perform multisubstrate bonding.
It also appears important to apply multiple coats of these agents so
that there is an adequately thick resin layer on top of the hybrid
This helps protect the DBA from early failure when the resin
composite shrinks during polymerization.
Recently have been marketed
Contains extremely small filler particles.
Include the products Prime & Bond NT (Dentsply/Caulk) and Excite
Prime & Bond NT contains 7 nanometer fillers , has a greater
concentration of resin and a smaller molecular weight resin.
These changes, are said to make the DBA tougher, stronger, and able to
cover adequately with a single coat;
it is also claimed to penetrate dentin better, provide improved marginal
integrity, and have a low film thickness.
Ivoclar Vivadent’s Excite contains 12-nanometer fillers and is packaged
in a single-use capsule. It is very fast to apply, covers dentin in one coat,
and comes with a graphics-only instruction card.
Introduced in the late 1990s and early 2000s .
Self-etching primer and adhesive:
◦ Available in two bottles:
◦ Primer is applied prior to the adhesive
◦ Water is the solvent in these systems.
Self etching adhesive
◦ Available in two bottles:
◦ A drop from each bottle is taken, mixed and applied to the tooth surface, for
example, Prompt L-pop.
Mechanism of bonding: In these agents as soon as the
decalcification process starts, infiltration of the empty spaces
by the dentin bonding agent is initiated
Comparable adhesion and bond strengths to enamel and dentin
Reduces postoperative sensitivity because they etch and prime simultaneously
They etch the dentin less aggressively than total etch products
The demineralized dentin is infiltrated by resin during the etching process
Since they do not remove the smear layer, the tubules remain sealed, resulting in less
They form a relatively thinner hybrid layer than traditional product which results in
complete infiltration of the demineralized dentin by the resin monomers. This results in
increased bond strength
Much faster and simpler technique
Less technique sensitive as fewer number of steps are involved for the self etch system
They achieve the same objective as the sixth generation systems except that they simplified
the multiple sixth generation materials into a single component, single bottle one-step self-
etch adhesive, thus avoiding any mistakes in mixing.
Developed in late 2000s
All in one concept, i.e. components available as single component
Uses self etch primer
Good bond strength.
No postoperative sensitivity.
Also have disinfecting and desensitizing properties.
They have attained consistently lower bond strengths than the fourth and fifth-generation
Laboratory studies show that bond strengths and margin sealing to
be equal to the sixth-generation systems.
iBondTM is a seventh-generation, single-component, no-mix, one-
step application dental adhesive with an etchant, adhesive,
desensitizer, and photoinitiator.
Laboratory testing confirms that iBondTM has physical
characteristics similar to other self-etching adhesives and may be
used in all clinical situations where dental adhesives are required.
GC has also introduced one component self-etching light-cured adhesive under
trade name of G-BOND.
STEP 4TH GEERATION 5TH
Etchant Etchant Self etching
Resin/sealer Self etching,
A new category of composite resin restorative materials, which
include what could be referred to as an “eighth-generation”
bonding system, has just become available for use.
This new technology features a bonding agent which is contained
within the composite resin restorative material.
A self-etching, self-adhering flowable composite technology
eliminates the need for a separate bonding application step with
composites for direct restorative procedures.
Utilizing previous adhesive technology (found in the OptiBond
system [Kerr]), this new self-etching, self-bonding flowable
composite resin system (Vertise Flow [Kerr]), simplifies the
placement of direct composite restorations.
Since fifth-, sixth- and seventh-generation systems are incompatible with self-
cure materials and dual-cure materials that cannot be effectively light-cured
Futura bond DC dual cured
It is dual-cured and works with all light-, self- or dual-cured resins
It takes only 35 sec. from start to finish
It needs only one coat .
Futurabond DC cures without any light in the self-cured mode. This is a big
advantage for root canal cementation.
Futurabond DC eliminates the problem of the “pooling effect” with moisture
A new system would be developed that had the best attributes of the fourth generation and the ease of
the sixth-generation bonding systems, and that system is Surpass® from Apex
Surpass is an eighth-generation material because it is very different from other generations.
It consists of three bottles: an etchant/conditioner, a primer, and a separate hydrophobic bonding resin.
In that regard, it resembles fourth-generation materials but the etchant/conditioner is not rinsed from
Thus, Surpass also has characteristics of the sixth generation—the ease of a no-rinse system but the
performance of a fourth-generation system.
Surpass 1 is applied to the dentin and enamel for about 10 seconds, agitating gently.
Three brushfuls of Surpass 2 are then applied right onto the wet preparation.
Once the three brushfuls have been applied, the preparation is dried thoroughly for 10 seconds. It
cannot be overdried and the drier the tooth is following application of Surpass 2, the better the
Then a layer of Surpass 3 is applied to the preparation and light-cured for 10 seconds.
This is the only technique for Surpass no matter what kind of procedure is being performed..
Surpass may be used with any resin materials—dual-cure, self-cure, and light-
cure—and no catalysts are required.
For use with indirect restorations, Surpass is simply made very thin prior to light-
For direct restorations, the bonding resin can be made to the desired thickness,
although a thin uniform layer is recommended.
Surpass dentin bond strengths have been demonstrated to be in the mid-50 MPa
A dentin bonding agent is a low viscosity unfilled or semifilled resin for easy penetration and formation
of a hybrid layer.
When a bonding agent is applied, part of it penetrates into the collagen network, known as
intertubular penetration and the rest of it penetrates into dentinal tubules called intratubular
In intertubular penetration, it polymerises with primer monomers forming a hybrid layer/resin
Hybridization is the process of formation of a hybrid layer.
The hybrid layer is the phenomenon of formation of a resin interlocking in the
demineralized dentin surface. The hybrid layer is responsible for micromechanical bonding
between tooth and resin
When dentin is treated with a conditioner, it exposes the collagen fibril network with interfibrillar
These spaces are filled with low viscosity monomers when primer is applied.
This layer formed by demineralization of dentin and infilteration of monomer and subsequent
polymerization is called the hybrid layer.
Hybridoid layer is that area of demineralized dentin into which resin fail to penetrate
1. Top layer: Consists of loosely arranged collagen fibrils and interfibrillar spaces filled with resin.
2. Middle layer: Consists of interfibrillar spaces in which hydroxyapatite crystals have been replaced
by resin monomer because of the hybridization process.
3. Bottom layer: Consists of almost unaffected dentin with a partly demineralized zone of dentin
The hybrid layer promotes good bond strength,
Behaves like an impermeable membrane that can prevent noxious stimuli from invading
pulpal tissue through dentinal tubules.
Hybridized dentin reduces the
risk of microleakage,
incidence of secondary caries and
Diagrammatic presentation of different zones of hybrid layer
Concerns have been raised that aggressive etching of the dentin may cause demineralization to a depth
that might be inaccessible to complete resin impregnation.
If this occurred, a collagenous band at the base of the hybrid, not impregnated by resin, would
dramatically weaken the resin-dentin bond and consequently, the durability of bond.
Incomplete resin penetration has been described as causing a microporous dentinal zone at the base of
hybrid layer (Sano et al, 1994) , which is thought to be a pathway for nanoleakage of fluids, causing
hydrolysis of collagen and a reduction in longevity of bond.
• By etching dentin, the smear layer and minerals from it are removed, exposing the collagen fibers
• Areas from where minerals are removed are filled with water.
• This water acts as a plasticizer for collagen, keeping it in an expanded soft state.
• Thus, spaces for resin infiltration are also preserved. But these collagen fibers collapse when dry
and if the organic matrix is denatured.
• This obstructs the resin from reaching the dentin surface and forming a hybrid layer
• The desired effect of acid etching, which is increased permeability
• For this reason, presence of moist/wet dentin is needed to achieve successful dentin
• When primer is applied to wet/moist dentin, water diffuses from the primer to the organic
solvent and the solvent diffuses along with the polymers into the demineralized dentinal
matrix and tubules.
Schematic (on the left) and transmission electron micrograph, on the right, of the “over-wet” phenomenon. In the
total-etch, wet bonding technique, there is the danger that some regions in complex cavity preparations (such as
proximal boxes) may be too wet. When single bottle primer/adhesives are applied, the solvent may diffuse into the
water, forcing adhesive monomers to undergo phase changes, forming blisters, resin globules, etc. Note that
although the etched intertubular dentin has taken up resin to form hybrid layers (red zone on left) the adhesive
(blue) did not form resin tags, but left the tubules in communication with microblisters filled with water (light blue).
These blisters may compress when the restoration is under occlusal function, forcing dentinal fluid toward the pulp
and causing post-operative sensitivity. This is one of the possible complications of this technique-sensitive
Transmission electron micrographs of dentin bonded with an all-in-one adhesive, then placed in
37ºC water for 24 hrs prior to soaking in silver nitrate to demonstrate the presence of water-filled
(now silver-filled) channels called “water trees” (finger-pointers) extending from the hybrid layer
(H) and passing through the cured adhesive layer. The black silver deposits indicate where there
were water-filled channels. Such water trees do not form in self-etching primer adhesives.
Modern dentin adhesives systems are classified as
Group one: Modify the smear layer and incorporate in the bonding process. They are
further classified in one step and two step smear layer modifying system.
Group two: Complete removal of the smear layer. Again they are further classified in two
and three step removing systems, depending on a combined or a separate application of a
primer and adhesive resin.
Group three: Dissolve the smear layer.
3-COMPONENT SYSTEMS (E + nP + B)
Scotchbond Multipurpose Plus (3M)
Bond-It (Jeneric / Pentron)
All-Bond 2 (BISCO)
Tenure A/B/S (Denmat)
2-COMPONENT SYSTEMS (nEP + B)
Clearfil SE Bond & LinerBond 2v (Kuraray)
Tyrian SPE (Bisco)
Optibond Solo SE Plus (Kerr)
Fluoro Bond (Shofu)
UniFil Bond (GC)
Mac Bond II (Tokuyama)
2-COMPONENT SYSTEMS (E + nPB)
Syntac Single Component (Ivoclar)
Ecusit Primer/Mono (DMG Hamburg)
One Coat Bond (Coltene / Whaledent)
Bond-1 (Jeneric / Pentron)
Tenure Quik with Fluoride (Denmat)
Solid Bond (Hereaus-Kulzer)
Imperva Bond (Shofu)
EG Bond (Sun Chemical)
Easy Bond (Parkell)
Paama 2 and Stae (SDI)
Prime&Bond NT (Dentsply)
Optibond Solo and Solo Plus (Kerr)
OSB Bonding System (ESPE)
1-COMPONENT SYSTEMS (nEPB)
AQBond (Sun Medical)
Adper Prompt or LP3 (3M-ESPE)
Solist (One-bottle-bond) (DMG Hamburg)
Xeno III (Dentsply)
Besides the use of dentin bonding agent as a normal part of resin bonding, they have other clinical
◦ Metal-Resin bonding of indirect resin-bonded inlay, onlay, crown or veneer.
◦ As amalgam bonding agent.
◦ Prevention and treatment of hypersensitivity.
◦ In establishing apical and coronal seal of the root along with resin
◦ Pulp capping agent
◦ As a protective coat for glass ionomer restorations
A technique to bond amalgam to the
Conserve more tooth structure by reducing the need to remove sound tooth tissue for
Increased Amalgam retention.
Reduce marginal leakage
Reduce the need for dentine pins.
Potentially reduce sensitivity
Improve fracture resistance
Improved amalgam margins
Resin Cements ( Panavia)
Adhesive Bonding Agents
-initially designed for composites
Etching dentine opens up dentinal tubules enabling adhesive resin to flow into dentine
and is retained micromechanically
Adhesive resin adheres to amalgam roughness micromechanically and by 4-META
Increased amalgam retention
◦ YES, if cavity lacks mechanical retention
Avoids risk of using pins
◦ YES, 20% of pins perforate, 80oC rise
Improved amalgam margins
◦ Depends on adhesive used. Panavia weakens amalgam at margins
◦ Technique may reduce incidence of ditching
◦ YES, if large cavity
◦ NO, if small cavity
Not recommended for routine amalgam cavities with sufficient mechanical
retention and undercuts. No evidence of increased benefit to balance increased
Useful for large multisurface amalgams to avoid use of pins
Useful for amalgam repairs
Some easier to use than others
Place matrix band ( lightly vaselined)
Etch 10% phosphoric acid
Wash and dry
Apply adhesive ( Kerr Optibond solo)
Blow off excess solvent
Increased cost of restoration
Not in use long enough to permit adequate evaluation of clinical performance
Adhesion may breakdown over time
Amalgam is an excellent core build-up material for posterior teeth
Excellent interim restoration for posterior teeth .
Adhesives can be used to improve retention in large amalgam restorations and
Adhesives and preparation features can often substitute for pin retention for cores
The choice may be Confusing.
It is easy for the clinician to believe that a newsystemis
betterover the old onesbut this may not alwaysbe true.
Chemistryis more important than the company.
Technique is more important than the material.
What we have to choose: