DENTIN BONDING AGENTS

1. DENTIN BONDING
AGENT
PRESENTED BY
DR. DRASTI SHRIVASTAVA

2.  INTRODUCTION
 HISTORY
 CLINICAL USE
 BONDING TO ENAMEL
 BONDING TO DENTIN
 COMPOSITION OF BONDING SYSTEM
 CLASSIFICATIONS OF DENTIN BONDING SYSTEMS
 TOTAL ECH TECHNIQUE
 SELF ETCH SYSTEMS
 SMEAR LAYER
 ADVANTAGEOF ADHESION
 FAILURE OF ADHESION
 CONCLUSION

3.  Restorative dentistry plays an important role in
restoring the tooth tissue to its form, function
esthetics and in maintaining the physiologic
integrity in harmony with the surrounding hard and
soft tissues.
 Many of the restorative material used did not
adhere to enamel to dentin by physical and or
chemical interactions thus increasing the chances
of micro-leakage at restoration tooth interface.

4.  Therefore the introduction of adhesive restorative
materials has reduced the need for an extensive
tooth preparation.
 In order to successfully accompolish this, dentin
bonding systems have been introduced which bond
the composite resin to the tooth structure.

5. Dentin Bonding
• The process of bonding a resin to conditioned dentin.
Dentin Bonding Agent
• A thin layer of resin between conditioned dentin and the
resin matrix of a composite.

6.  Buonocore (1955): Acid etching technique
 Bowen (1957): Development of BISGMA.
 Causton(1965): How primers work.

7.  Knight et al( 1971) Urethane Dimethacrylate.
(ICI Dental).
 Forster and Walker (Amalgamated Dental
Company)1975.
 Urethane di-methacrylate resin for use in resin
composite dental materials.
Higher molecular weight,
Lower viscosity
Toughness
Less staining than BIS GMA.
 Gwinnet and Silverstone( 1975) described three
patterns of etching of enamel.

8. Nakabayashi et al(1982) Hybrid layer
Ferrari et al( 1997- 2003) Development of one bottle
bonding systems.
Sixth and Seventh generation bonding systems.
Fusayama ( 1987)
Concept of total
etching and bonding.
John Kanca ( 1990s)
Wet bonding technique

9.  Bonding of directly paste resin based restorative
material.
 Bonding of indirect placed restorative material.
 Bonding of ceramic and amalgam restorations.
 Bonding of prefabricated and cast posts.
 Bonding orthodontic brackets
 Bonding periodontal splints
 Sealing of pits and fissures of posterior teeth.
 Reattachment of fracture tooth segments.
 Pulp capping.

10.  The word Adhesion comes from the Latin adherer
which means ‘to stick to’.
 “The state in which two surfaces are held together
by interfacial forces which may consist of valence
forces or interlocking forces or both”.(definition
given by the American Society For Testing and
Materials (SP No. D 907)
 Adhesion is the force or the intermolecular
attraction that exist between molecules of two
unlike substances when placed in intimate contact
with each other.

11. Adhesive-
The material that is used to cause bonding
Adherend-
The material to which it is applied

13.  The wetting ability of the liquid adhesive depends
upon the surface energy and cleanliness of the
adherend. Higher the surface energy greater would
be the wetting capacity.
 Important requirement for the occurrence of any of
these interfacial phenomena is that the two
materials being joined must be sufficiently wetted
with close and intimate relation.

14.  Wetting of a surface by a liquid is characterized by
the contact angle of a droplet placed on the surface

15.  The extent to which the adhesive will wet the
surface of the adherend is generally determined by
measuring the “contact angle” between the
adhesive and the adherend.
Smaller the angle, better the wettability

17.  Adhesive agents must have the ability to wet and
then to adhere to hard dental tissues. Dental
bonding systems contain monomers that have
hydrophilic and hydrophobic groups.

18.  An intermediate layer of resin, collagen, and
dentin produced by acid etching of dentin and
resin infiltration into the conditioned dentin

19.  When the primer is applied to a properly treated dentin
surface, they form “micro-tags” into the dentin
substrate, there by creating a zone of primer/resin
infiltrated dentin a the interface.
 Eg: Probond, Syntac, Scotch bond multipurpose, prime
and bond.

20.  In dentistry, bonding of resin to tooth surface is a
result of four possible mechanisms:
 Mechanical: Penetration of resin and formation
of resin tags within the tooth surface.
 Adsorption: Chemical bonding to the inorganic
component(hydroxyapatite) or organic
component (mainly type I collagen) of tooth
structure.
 Diffusion: precipitation of substances on the
tooth surface to which resin monomer can bond
mechanically or chemically.
 A combination of the above three mechanisms

21. Mechanism of bonding
Mechanical
Adsorption
Diffusion
A combination
of the above
three
mechanisms

22. .
 BY ACID ETCHING--
 Increase micro mechanical bond increase surface
energy
 ACID – ETCHING TECHNIQUE--
 Process of roughening a solid surface acid and
thoroughly rinsing the residue to promote micro
mechanical bonding of an adhesive to the surface.
 Acid etching transforms the smooth enamel into an
irregular surface and increases its surface free 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 then then polymerized,
and the material becomes interlocked with the enamel
surface

23. Bonding of enamel
Application of a fluid resin-based material to the
irregular etched surface
Acid etching transforms the smooth enamel into
an irregular surface
Monomers in the material are then then
polymerized
Process of roughening a solid surface

24. Percentage of elements used
 37% Phosphoric Acid
Acid application time
 15sec

25.  Enamel only bonding system contains an unfilled
liquid acrylic monomer mixture placed onto acid
etched enamel. The monomer flows into the
intersitces between and within the enamel rods.
 Enamel bonding depends upon resin tags
becoming interlocked with surface irregularities
created by etching.

26.  Resin tags that form between the enamel rods and
peripheries are called Macrotags. A much finer
network of thousands of smaller tags form across
the end of each rod where individual
hydroxyapetite crystal have been dissolved
,leaving crypts outlined by residual organic
material. These fine tags are called Microtags.
Micro and macrotags are the basis for enamel
micromechanical bonding.

29. Dentine and enamel resin adhesion

30. For enamel bonding
 Addition of phosphoric acid for 30s
• Frosty appearance
• SEM structure show preferential etching of
hydroxyapatite prism
Cores
Periphery
 Penetration of methacrylate monomers into rough
surface provides micromechanical bonding

31. ETCHPATTERN
Enamel etching results in three different micromorphologic
patterns.8,9
1. Type I etch pattern involves the dissolution of prism
cores without dissolution of prism peripheries
Fig. 10.3Scanning electron micrograph SEM) of enamel
etched with 35% phosphoric acid for 15 seconds.

32. Fig. 10.4Transmission electron micrograph (TEM) of the
enamel-adhesive interface after application of Adper
Single Bond (3M ESPE) as per manufacturer’s
instructions. Acid etching with 35% phosphoric acid
opened spaces between enamel prisms (<arrows), allowing
the permeation of resin monomers between the crystallites
(<arrowheads). A, adhesive; E, enamel.

33. Fig. 10.5A,Scanning electron micrograph of enamel etched with 35%
phosphoric aci 15 seconds, denoting a type I etching pattern.
B,Scanning electron micrograph of enamel etched with 35% phosphoric
acid for 15 seconds, denoting a type III etching pattern.
2. Type II etch pattern is
the opposite of type I.
The peripheral enamel is
dissolved, but the cores are
left intact.
3. Type III etch pattern is
less distinct than the other
two patterns.
It includes areas that
resemble other
patterns and areas whose
topography is not related to
enamel prism morphology.

34. Enamel etching patterns

35. Phosphoric acid as an etchant
Buonocore:acid etching with 85% phosphoric acid for 30
sec
50 % phosphoric acid for 60 seconds
mono-calcium phosphate monohydrate precipitate
Concentrations below 25%
di-calcium phosphate monohydrate precipitate
Concentrations above 40%
Dissolve less calcium and etch patterns with poorer
definitions
37% for 15 sec is considered appropriate.

36. Enamel etching patterns

37. Acid washing
/ rinsing
Removes
smear layer
Dissolves HA
Drying shrinks remaining
Collagen polymer molecules
Rehydration /
priming
Swells collagen
MECHANISMOF DENTINe BONDING

38. Monomer penetration
MECHANISMOF DENTINE BONDING
Monomer polymerisation
And collagen entanglement

39. DENTIN PRIMER
Restorative resin
Dentin
Hydrophobic end
Hydrophilic end
Dentin primer
PRIMER
A hydrophilic, low
viscosity resin that
promotes bonding
to a substrate, such
as dentin

40. HYBRIDIZATION OF DENTIN
 Concept introduced in 1982 by Nobuo Nakabayashi
 HYBRIDIZATION (definition)
A process of diffusion and impregnation of resins
into the substrate of partially demineralised dentin
followed by its polymerization creating a “resin –
reinforced hybrid layers” or a “resin – dentin inter
diffusion zone.

41.  An intermediate layer of resin, collagen, and
dentin produced by acid etching of dentin and
resin infiltration into the conditioned dentin

42.  When the primer is applied to a properly treated dentin
surface, they form “micro-tags” into the dentin
substrate, there by creating a zone of primer/resin
infiltrated dentin a the interface.
 Eg: Probond, Syntac, Scotch bond multipurpose, prime
and bond.

43. Hybrid layer, Resin reinforced zone, or resin
infiltrated layer
Hybrid layer is the hydrophilic resin infiltrated surface
layer of collagen fibers in demineralized dentin.
Concurrent with hybridization, the resin tags seal the
unplugged dentinal tubules and offer additional retention
through hybridization of tubule orifices.

44. SHAG CARPET
APPEARANCE
Appears when dentin surface after
being acid etched is actively
scrubbed with an acidic primer
solution.
MECHANISM OF ACTION
The combined mechanical and
chemical action of rubbing the
acid etched dentin with an
acidic primer dissolves
additional mineral salts while
fluffing and separating the
entangled collagen at the
surface.

45. TUBULE WALL
HYBRIDIZATION
 Extension of the hybrid layer
into tubule wall area.
 Hermetically sealing the
pulpodentinal complex
against microleakage
 Especially protective when
bond fails at top or bottom of
the hybrid layer
 The resin tags keep tubules
sealed as they break off at the
level of hybrid layer.
Intertubula
r dentin
Resin
tag
Hybrid
layer
Adhesive
resin

46. LATERAL TUBULE
HYBRIDIZATION
 Formation of tiny hybrid
layer into the walls of
lateral tubule branches.
 This microversion of
hybrid layer typically
surrounds a central core
of resin called
microresin tag.
Micro resin tag

47. Dentin Bonding Agent, DBA
Early DBA were hydrophobic, bonded
directly to the dentin smear layer.
Bond strengths＜6MPa.
Later DBA removed the smear layer but
tended to over-etch dentin.
Bond strengths≈10~12MPa.

48. DBA were chemically modified to be
more hydrophilic.
Bond Strengths≈18~20MPa.
Careful dentin conditioning,
Coupled with hydrophilic primer,
Bond Strength≈22~35MPa.

49. While instrumenting , in addition to superficial
debris, it has been shown, using the scanning
electron microscope, that a layer of sludge
material was always formed over the surface of
dentinal walls. This layer of debris has been
called the smearlayer.

50. ROLE OF SMEAR LAYER IN DENTIN
BONDING
 Smear layer covers the normal structural component
of dentin by 1-2 um and penetrates 1-5 um into the
tubules to form smear plugs. It has two phases
Solid phase
• Made up of cutting debris primarily denatured
collagen and mineral
liquid phase
• Made up of tortuous fluid filled channels
around the cutting debris

51. Reasons for removal of smear layer
 The exposed collagen provides reactive groups that
can chemically interact with the primers
 Amino groups may act as a catalyst to polymerization
reaction
 Exposed collagen promotes micro mechanical
bonding to resin by providing a frame work
NOTE- The recent generation of adhesive involves
modification of smear layer as it is believed to greatly
improve the bond strength to dentin

52. Reasons for retaining the smear layer
 Retention of smear layer lowers the dentin
permeability
 Prevents decrease in the bond strength seen with
some bonding systems as deeper dentin is prepared
 Greatly lowers the pulpal pressure on bond strength

53. DENTIN BONDINGAGENTS

54. DBA YEAR AGENT FEATURE EXAMPLE
1ST
Gen
Early 1950s NPG-GMA High poly shrinkage &
thermal expan
Cervident
2ND
Gen
Late 1960s
& Early
1970s
PO4 in resin+
Ca in smear
layer
Insignificant chemical
bonding
Clearfill Bond
F, Bondite
3RD
Gen
Mid 1980s HEMA, 2%
aqueous nitric
acid
4 Steps: cond, prim,
adhesive, comp. Smear
layer removal
Scotch bond 2
4TH
Gen
Early to mid
1990
BisGMA,
UDMA with
TEGDMA,
HEMA
Total etch technique, wet
bonding
All bond 2
Imperva bond
5TH
Gen
Mid to late
1900s
Simplified
version of 4th
Gen
Two step system Single bond,
one step
6TH
Gen
Early 2000s Phenyl P,
HEMA
I: self etching primers
II: All in one
Clearfill SF
bond
7TH
Gen
Late 2002-
Early 2005
Desensitizing
agent added
More prone to phase
separation
I-bond, G-bond

55. 1st Generation DBA
NPG-GMA chelate with calcium in dentin=water-resistant
chemical bond
Example:
Cervident (SS Whitte)
Low bond strength: 2-3 MPa
1ST Gen Early 1950s NPG-GMA High poly shrinkage
& thermal expan
Cervident

56. 2nd Generation DBA
•DBA bonding to the inorganic component of dentin:-
Phosphate Group
Amino Group
•DBA bonding to the organic component of dentin:-
Iso-cyanate Group
Carboxylic Acid Group
Lack of Hydrolytic Stability
Bond primarily to smear layer
Limited bond strength: 5-6 MPa
2ND
Gen
Late 1960s &
Early 1970s
PO4 in resin+ Ca
in smear layer
Insignificant
chemical bonding
Clearfill
Bond F,
Bondite
Example:
Clearfill Bond System F(Kuraray), Bondlite (Kerr/Sybron),
Scotch Bond (3M)

57. 3rd Generation DBA
Modification/Removal of Smear Layer
Steps:-
1. Application of dentin conditioner (HEMA + Maleic/nitric acid)
2. Application of the primer
3. Application of the adhesive (unfilled resin)
4. Placement of resin-based composite
Use milder acids:-
Tenure: Ferric oxalate in 2.5% nitric acid followed by acetone solution
of NTG-GMA
Gluma:- EDTA (tublicid) remove smear layer, then a HEMA solution
applied
Scotch bond II: HEMA acidified with maleic acid, adhesive-
HEMA+BisGMA
C&B Metabond: 10% of citric acid & ferric chloride, HEMA as primer
3RD
Gen
Mid
1980s
HEMA, 2%
aqueous nitric acid
4 Steps: cond, prim, adhesive,
comp. Smear layer removal
Scotch
bond 2

58. 4th Generation DBA
ACID: 7.5 Micrometers Demineralization
PRIMER:
Increases the surface energy of the
Substrate.(NPG GMA, BPDM)
UNFILLED RESINS40%BisGMA, 30%UDMA,30%HEMA)
AGENTS
All bond 2(Bisco Dental)
Amalgam- bond(Parkell)
Clearfil Liner Bond(Kuraray)
Imperva Bond(Shofu Dental)
Optibond(Kerr)
Scotch bond multipurpose(3M
Dental)
Bond strength: 18 Mpa
1ST Gen Early 1950s NPG-GMA High poly shrinkage
& thermal expan
Cervident

59. 5th Generation DBA
MECHANISM OF ACTION
Micromechanical retention by-
 Penetration into partially opened tubules
 Hybrid layer
 Chemical interactions using first and second order bonding
AGENTS
Prime and Bond 2.1
Prime and Bond NT( Dentsply
Caulk, Milford, Delaware).
Prime and Bond 2.0( Dentsply
De Trey, Konstanz, Germany)
Single Bond( 3M ESPE)
Optibond Solo plus( Kerr
Corporation, Orange California)
Good Bond strength
5TH
Gen
Mid to
late 1900s
Simplified version of
4th Gen
Two step system Single bond,
one step

60. 5th Generation DBA
Acetone or ethanol solvent displaces water and carries the resins into collagen.
The moist bonding technique used with etch-andrinse adhesives prevents the
collagen collapse that occurs on drying demineralized dentin.
Moist
or wet
bonding
5TH
Gen
Mid to
late 1900s
Simplified version of
4th Gen
Two step system Single bond,
one step
Moist bonding
technique

61. 6th Generation DBA
Dissolution of
smear layer and
HA by
methacrylated
phosphate
Dissolved components bound into polymerised matrix
Solvent evaporates
6TH
Gen
Early
2000s
Phenyl P, HEMA I: self etching primers
II: All in one
Clearfill SF
bond

62. 6th Generation DBA
TYPEI TWOSTEP/ NON RINSINGCONDITIONER/ SELFETCHPRIMERSYSTEMS
SIMPLICITY
Introduced by Dr. John Kanca.
Ability to stick to all methacrylate resins
light cured, dual cured or self cured.
Film thickness is sufficiently thin, so can be
used to bond posts to endodontically treated
teeth and to bond indirect resin inlays.
CLEARFIL SE BOND
Comes close to the ideal bonding agent.
Film thickness is slightly high .
Questions about its ability to stick to
some self cured resins.
6TH
Gen
Early
2000s
Phenyl P, HEMA I: self etching primers
II: All in one
Clearfill SF
bond

63. 6th Generation DBA
TypeII 6 th GenerationBondingagent:Onestep/Selfetchingadhesives/Allinone systems
PROMPT L POP
It has 3 compartments-
Compartment 1: Containing
methacrylated phosphoric acid, esters
photoinitiators, stabilizers.
Compartment 2: Contains water,
complex fluoride and stabilizers.
Compartment 3: Has a microbrush.
Mixing ratio is 4:1
Demineralized dentin is then
loaded with prompt L pop
monomers which will form hybrid
layers.
6TH
Gen
Early
2000s
Phenyl P, HEMA I: self etching primers
II: All in one
Clearfill SF
bond

64. 7th Generation DBA
iBond (Heraeus Kulzer)
Single step no mix bonding system
Five in one solution:
Etch
Disinfect
Desensitize
Prime and
Bond
7TH
Gen
Late 2002-
Early 2005
Desensitizing
agent added
More prone to phase
separation
I-bond, G-
bond

65. 7th Generation DBA
GC s G bond
4 MET monomer :strong consistent bond to dentin
Phosphoric acid ester monomer : Consistent bond to
enamel.
7TH
Gen
Late 2002-
Early 2005
Desensitizing
agent added
More prone to phase
separation
I-bond, G-
bond