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DEPT. OF CONSERVATIVE DENTISTRY
& ENDODONTICS
1
 Introduction
 History
 Adhesion
 Adhesion to Enamel
 Bonding to Dentin and its problems faced
 Ideal Requirements o...
 Hybrid layer
 Classification of Dentin Bonding Agents
 Adhesives
 Clinical indications of Dentin Bonding Agents
 Con...
 Bonding/ adhesion comprise a complex set of physical, chemical and
mechanical mechanisms that allow the attachment of on...
1. Provides resistance to separation of an adherend.
2. Distributes stress along bonded interface.
3. Seals the interface ...
• Development of epoxymolecule byCastan
1938
• Glycerophosphoricaciddimethacrylatedeveloped by
Dr.OscarHaggart1951
• Buono...
• Caustondescribedhowprimers work
1965
•GwinnetandSilverstone described threepatternsof
etchingof enamel.
1975
• Bowen,Cob...
• Ferrari described about the bonding
mechanism ofone bottle adhesive system.1997
• Ferrari evaluated bonding abilityof6th...
ADHESION – (Latin : to stick)
It is the force or the intermolecular attraction that exists between molecules of two
unlike...
1. Physical - based on secondary forces
– Vander Waals forces, hydrogen bonds, dispersion forces(
speciallywhen surfaces a...
1. Surface energy- Generally, the harder the surface is the higher the
surface energy willbe and so better willbe the adhe...
4. Surface Contamination
 Thesubstrate surface should be cleanas contamination prevents the adhesion.
 Adhesive should b...
 Enamel
 The hardest tissuein the human body.
 Consists of 95 percent mineralized inorganic substance.
13
 To bond to enamel, it is very important to focus on the mineral
component (hydroxyapatite) of enamel.
• Adhesion to enam...
Effects of Conditioning / Etching:
1. Removes 10 µM of surface enamel & creates amicroporous layer.
2. Increases wettabili...
 Buonocore, 1955
 was the first to reveal the adhesion of acrylic resin to acid etched
enamel.
 used 85 % phosphoric ac...
 If the concentration is greater than50 percent:
 monocalcium phosphate monohydrate may get precipitated, that
can be ri...
 Originally,the etching time suggested was 60 sec.
 Currently, it has been reduced to 15 sec as it produces same surface...
Acid etching
smooth enamel converted into irregular surface [surface free energy ]
Resin monomer penetrate (b/c of low vis...
 Macrotags–resin tags formed at periphery of enamelrods (between prisms )
 Microtags - smaller tags formed at end of eac...
Various etchants used –
1. Phosphoric acid – as liquid or gel.
2. Sulphuric acid 2 %
3. Citric acid
4. Maleicacid 10 %
5. ...
Micromorphologic Patterns of etching of Enamel
A properly etched enamel surface gives a frosty white appearance on
drying...
 After etching, the enamel surface should be throughly rinsed with a
continuous stream of water spray for 5-10 sec so tha...
 Generally, enamel bonding agents contain Bis-GMA or UDMA with
TEGDMA added to lower the viscosity of the bonding agent.
...
 Bonding to dentin has been proven more difficult and less reliable than to
enamel.
 This is basically because of differ...
PROBLEMS IN BONDINGTO DENTIN
1) It has considerable amount of organic material & water (30% organic
material;20%fluid).
2)...
6) Cut dentin surface is covered by smear layer, that fills the orifice of
dental tubules, & blocks dentin permeability up...
 ETCHENTS/ CONDITIONERS
 PRIMERS
 ADHESIVES
 FILLERS
28
 ORGANIC ACID:- Maleicacid,EDTA ,citric acid, tartaricacid.
 INORGANIC ACID:- phosphoric acid, nitric acid.
 POLYMERIC ...
• HEMA:2-HydroxyethylMethacrylate
• PENTA:DipentaErythritolPentaAcrylateMonoohosphate
• NPG-GMA:N- PhenylGlycineGlucidylMe...
 Hydrophobicmonomers
 BIS-GMA
 UDMA
 Diluent
 TEGDMA
 Wettingagent
 HEMA
31
FILLERS
Most of the bonding agents are unfilled.
May contain inorganic fillers 0. 5% to 40% by wt. microfillers, or
nano...
CONDITIONING OF DENTIN
Defined as removal or modification of the smear layer, to create a
surface, capable of micromechani...
Conditioningcan be done by-
A. Chemicals
1. Acids
2. Calciumchelators
B. Thermal
 Lasers
C. Mechanical
 Abrasion
34
CHEMICALS :
1. ACIDS:
1. Phosphoric acid
2. Sulphuric acid: [2 % for 30 sec.]
 As effective as phosphoric acid.
3. Nitric...
4. Citricacid:
 10% citricacid+ 3% FeCl3 was recommended by Nakabayashi.
 Lately, Kuraray proposed a combination of 10% ...
6. Polyacrylicacid: [40%]
 Recent product.
 A 10 second application opens up the dentinal tubules but does not
effect pu...
2. CALCIUM CHELATORS:
 Chelators are used to remove the smear layer without decalcification of
the underlying dentin as o...
B. THERMALCONDITIONERS
LASERS
 Nd:YAG laser used at 10 to 30 pulses per second.
 The mechanism of action is through micr...
PRIMERS
 Theseare adhesion-promoters.
 Amphiphilic bifunctional molecules i.e have both hydrophillic and
hydrophobicmono...
 These solvents are volatile and displace water (water chasing ability) from the
dentinsurfaceandthemoistcollagennetwork....
SOLVENTSUSEDINPRIMERS:
1) Acetonebasedprimers
Advantages:
 Excellentwater chaser.
Disadvantages:
 Evaporatesquicklyafter...
2. Ethanolbased primers
Advantages :
Evaporates less quickly
Good surface energy and good penetration.
Disadvantages :
...
3. Water based primers –
Advantages :
Slow evaporation.
Have capacityto raise collapsed fibers.(9%-50%)
Disadvantages :
...
COMBINATION OF THE SOLVENTS THAT CAN BEUSED AS PRIMERS
1. Acetone & H2O
Eg: Tenure- quick
2. Acetone & ethanol
Eg: All bon...
 By etching dentin, the smear layer and minerals from it are removed,
exposingthecollagenfibers(&demineralizeddentin).
 ...
 Water removal also might permit additional hydrogen bonds to form
between collagen molecules, that previously were bonde...
 Introduced by Dr. JohnKanaandGwinnetin 1992.
 So, it refers to bonding in which acid etched dentin is moist and hence,
...
 To get moist dentin after etching, do not dry the dentin with compressed
air after rinsing awayetchant.
 Instead use hi...
 On rewetting, the collagen network assumes its original volume.
 The re-expansion during rewetting occurs because the s...
AZEOTROPHISM
 In acetone containg primers, when acetone comes in contact with water,
the boiling point of acetone is rais...
 Refers to the bonding in which the acid etched dentin is dry and so water-based
primersareused.
 Water-based primers ar...
 Hybridoid region/ Ghost hybrid layer is that area of demineralized
dentin into which resin fail to penetrate.
 It is on...
OVER-WETTINGPHENOMENON:
 If solvent of primer (acetone/ethanol) fails to remove water completely from
dentin,Over-wetting...
 The dentin surface may appear blister like with water being trapped
beneath the resin layer.
 Since blisters gets compr...
DISADVANTAGES OF WET BONDING TECHNIQUE
1. Technique sensitivity
2. Evaporation of acetone
 Increased monomerratio
 Decre...
ADVANTAGES OF DRYSURFACE
1. Frosted appearance of etched enamel can be verified.
2. Reduce risk of over wetting. (Rewettin...
AIR DRIED MOIST OVERWET
COLLAPSE OF COLLAGEN SWELLING OF COLLAGEN
NO RESIN PENETRATION LESSER SPACE AVAILABLE
FOR RESIN PE...
 Ideally a dentin bonding agent should have both hydrophilic and
hydrophobic ends. The hydrophilic end displaces the dent...
X
INORGANIC PART OF
DENTINE[Ca IONS]
ORGANIC PARTOF DENTIN
1. Amino(-NH)
2. Hydroxyl (-OH)
3. Carboxylate (-COOH)
4. Amide...
 Whenever tooth surface is cut with hand or rotary instruments , it causes small
particlesofthecuttoothsurfacetoadheretot...
 It hastwocomponents:
1. Thesuperficialsmear layer.
2. Smear plugsthatoccludethedentinaltubules.
 Opinionsdifferaboutthe...
 Zone where the adhesive resin of the dentin bonding agent
micromechanically interlocks within the intertubular dentin an...
 Whenabonding agentis applied,partofitpenetrates intothe collagennetwork,
known as intertubular penetration and the rest ...
1. Shag Carpet Appearance :
 Appears when dentin surface after being acid etched is actively
scrubbed with an acidicprime...
2. Tubulewall hybridization:
 Extensionof the hybrid layer into tubule wallarea.
 Hermetically sealsthe pulpodentinal co...
3) Lateral Tubule Hybridization :
 Formation of tiny hybrid layer into the wallsof lateraltubule branches.
 This microve...
 After etching, silica remnants from the phosphoric acid present on the exposed
collagen fibres, cannot be removedby vigo...
 Sodium hypochlorite is a non-specific proteolytic agent that effectively removes
organiccompoundsatroomtemperature.
 Th...
 Because of polymerization shrinkage, there is detachment of the adhesive resin
fromtheunderlyinghybridlayer.
 If a laye...
WATERTREES
 Water can pass from dentin around resin tags & form water filled channels that
project from the hybrid layer ...
1. According to generation.
2. According to adhesion strategy (number of clinicalapplications).
3. According to treatment ...
CLASSIFICATIONBASED ONTHE NUMBEROFCLINICALAPPLICATONS
STEPS AND HOW THEY INTERACTWITHTOOTHSTRCTURE
1) Total etch adhesives...
ON THE BASIS OFTREATMENT OFSMEAR LAYER
1) Removed:
TenureM
Mirage bond
Clearfil liner bond system
2) Modified:
All bon...
ACCORDINGTOTHEIRMODE OF CURING
1) Chemical cure:
Amalgabond plus
2) Light cure:
One bond
Gluma comfort bond
3) Dual cur...
C) DEPENDING ONTHE pH (VanMeerbecketal2003)
76
Mild ( pH ≥ 2 )
Cause
hybridization +
intermolecular
bonding
Intermediary s...
 Intermolecular bonding: Hydroxyapatite acts as a receptor for additional molecular
interactions with specific carboxyl o...
ONTHE BASISOF SHEAR BOND STRENGTH(EICK etal)
1)5-7Mpa:
 Scotchbonddualcure
 Gluma
2)8-14Mpa
 Tenure
 Miragebond
3)17-2...
 Developed in 1960s.
 First generation adhesives started with the development of NPG-GMA (Comonomer).
 It chelates with...
 Developed in 1978.
 Low bond strength (1–5 Mpa).
 It consisted of a phospahate – ester material.
-velycharged Binds to...
 Conceptwastomodifythesmearlayer,rather thanremoving.
 Thisallowspenetrationofacidicmonomers.
 For modification of smea...
 So, overall there is preservation of modified smear layer with slight
demineralizationoftheunderlyingintertubulardentins...
 Based on removal of smearlayer to permitresin bonding to the underlying dentin.
 Removal of smear layer via acid etchin...
PARTIAL/
TOTAL
REMOVAL
OF SMEAR
LAYER
ADHESION
PROMOTER
COPOLYMERIZE
WITH PRIMED
DENTIN & ALSO
WITH
COMPOSITE
OVER IT
EXPO...
 As the technique involves simultaneous application of acid to
enamel & dentin, this method is commonly k/s TOTAL ETCH
TE...
 This was done to reduce number of steps
&soeasytouse.
 As primer & bonding agent are combined
into a single solution, t...
 Also known as NON RINSING
CONDITIONER [NRC]/ SELF
PRIMING ETCHANTS [SPE].
 In contrast to conventional
etchants, SEPs a...
TYPE I
SELF ETCH PRIMER & ADHESIVE
 2 bottle system.
 Components of both the bottles
are applied separately. i.e self
et...
 DISADVANTAGE:
1. SEPs do not etch enamel as well as phosphoric acid, & so do not provide higher
bondstrength/betterclini...
SIMPLICITY
Introduced by Dr. JohnKanca.
Its film thickness is sufficiently thin, so can be used to bond posts to
endodon...
 Ex:
 Prompt LPop
 Touch andBond
 Brushand bond
 Xeno III
Etchant
Primer Adhesive
All in one
adhesive
91
 Both the sixth and seventh generation adhesives are self etching, self priming
adhesives, but the seventh generation bon...
iBond
Single step, no mix bonding system.
Five in one solution:
a) Etch
b) Prime
c) Bond
d) Disinfect
e) Desensitize
93
G-BOND
 Based on nano interaction technology.
Nanointeractiontechnology
 G-BOND forms a non-conventional interface with ...
EIGHTGENERATION
 This new technology features a bonding agent which is contained
within the composite resin restorative m...
CLINICALINDICATIONS OFDENTINBONDINGAGENTS:
1. Bondingofdirectlyplacedresinbasedrestorativematerials.
2. Bondingofindirectl...
SIDE EFFECTS
1) Sensitizing reaction (burning sensation) : Seen in patient with a
hypersensitivity to any of its ingredien...
CLINICAL SUCCESS OR FAILURES IN BONDING :
 Can occur at various levels:
1. Between mineralized anddemineralized dentin.
2...
2)Archtype:
 Adhesion is better in case of maxillary arch than mandibular arch due to
lesserchancesofmoisturecontaminatio...
REFERENCES:
1) Sturdevant’sArt AndScienceOfOperativeDentistry,5th Edition.
2) Phillip’sScienceOfDentalMaterials,11th Editi...
101
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Bonding agents used in dentistry

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Bonding agents used in dentistry

  1. 1. DEPT. OF CONSERVATIVE DENTISTRY & ENDODONTICS 1
  2. 2.  Introduction  History  Adhesion  Adhesion to Enamel  Bonding to Dentin and its problems faced  Ideal Requirements of DBA  Composition of DBA  Conditioning of Dentin  Primers, Mechanism of Action of Dentin Bonding Agents 2
  3. 3.  Hybrid layer  Classification of Dentin Bonding Agents  Adhesives  Clinical indications of Dentin Bonding Agents  Contra-indications of Dentin Bonding Agents  Conclusion  References 3
  4. 4.  Bonding/ adhesion comprise a complex set of physical, chemical and mechanical mechanisms that allow the attachment of one substance to another.  Bonding agents can be defined as material of low viscosity, when applied on the tooth surface, forms thin film after setting.  This thin film strongly bonded to tooth surface, on which the viscous composite restorative resin is applied. This sets forming an integrated resin restoration. 4
  5. 5. 1. Provides resistance to separation of an adherend. 2. Distributes stress along bonded interface. 3. Seals the interface via adhesive bonding and hence reduces microleakage. 5
  6. 6. • Development of epoxymolecule byCastan 1938 • Glycerophosphoricaciddimethacrylatedeveloped by Dr.OscarHaggart1951 • Buonocoredeveloped acid etchingtechniquewith phosphoricacid1955 •Buonocoredeveloped the first dentinbondingagents. 1956 •BowengaveBISGMA resin system 1957 6
  7. 7. • Caustondescribedhowprimers work 1965 •GwinnetandSilverstone described threepatternsof etchingof enamel. 1975 • Bowen,CobbandRapsondeveloped multilayer adhesivesystem. • Nakabayashireported thepresence of hybridlayer 1982 • Fusayama gave theconcept of totaletchingand bonding1987 • Kanca described the conceptof wetbonding 1990s 7
  8. 8. • Ferrari described about the bonding mechanism ofone bottle adhesive system.1997 • Ferrari evaluated bonding abilityof6th generation bonding systems.2000 • Ferrari developed the seventh generation bonding agents.2003 8
  9. 9. ADHESION – (Latin : to stick) It is the force or the intermolecular attraction that exists between molecules of two unlike substances when placedin intimate contact with eachother. ADHESIVE – It is the substance that promotes adhesion of one substance or material to one another. ADHEREND – A material substrate that is bonded to anothermaterial by meansof anadhesive. 9
  10. 10. 1. Physical - based on secondary forces – Vander Waals forces, hydrogen bonds, dispersion forces( speciallywhen surfaces are smooth and polished ) 2. Chemical - based on primary forces – covalent, ionic, metallic bonds. 3. Mechanical -based on penetration of one material into another at microscopic level (when surfaces are rough). 10
  11. 11. 1. Surface energy- Generally, the harder the surface is the higher the surface energy willbe and so better willbe the adhesion. 2. Wetting- High surface energy , better wetting and better adhesion ( reduced irregularities ). 3. Contact angle- Lower the contact angle, better wetting and better adhesion. For good adhesion, the contact angle should be < 900. The zero contactangle is the best to obtain wetting. 11
  12. 12. 4. Surface Contamination  Thesubstrate surface should be cleanas contamination prevents the adhesion.  Adhesive should be able to fill their irregularities making the surface smooth allowing proper or intimate contact . 5. Water  Thehigher the water content, the poorer is the adhesion.  Water can react with both materials by the high polar group and form hydrogen bond which can hamper the adhesion. 12
  13. 13.  Enamel  The hardest tissuein the human body.  Consists of 95 percent mineralized inorganic substance. 13
  14. 14.  To bond to enamel, it is very important to focus on the mineral component (hydroxyapatite) of enamel. • Adhesion to enamel is mainly by micromechanical methods. For this, etching isdone. 14
  15. 15. Effects of Conditioning / Etching: 1. Removes 10 µM of surface enamel & creates amicroporous layer. 2. Increases wettability. 3. Increases surface area. 4. Increases surface energy. Bond strengthof composite to etched enamel: 15-25 MPa. [ENOUGH TO RESIST POLYMERIZATION SHRINKAGE] 15
  16. 16.  Buonocore, 1955  was the first to reveal the adhesion of acrylic resin to acid etched enamel.  used 85 % phosphoric acid.  Silverstone revealed that the optimum concentration of phosphoric acid should range between 30 – 40% to get a satisfactory adhesion to the enamel.  Percentage of etchants used: 37% 16
  17. 17.  If the concentration is greater than50 percent:  monocalcium phosphate monohydrate may get precipitated, that can be rinsed off. (It prevent further dissolution).  If concentrations lower than 27% percent:  dicalcium phosphate monohydrate is precipitated, which cannotbe removed easily and interferes with adhesion.
  18. 18.  Originally,the etching time suggested was 60 sec.  Currently, it has been reduced to 15 sec as it produces same surface roughness as a 60 sec etch time. Teethrequiringlonger application- Acid resistant teeth ( with high F content/ Fluorosis). Primary teeth (More aprismatic). 18
  19. 19. Acid etching smooth enamel converted into irregular surface [surface free energy ] Resin monomer penetrate (b/c of low viscosity) into the irregular etched surface [aided by capillary action]. Monomer polymerize, material become interlocked within the enamel surface. [Microtag formation] 19
  20. 20.  Macrotags–resin tags formed at periphery of enamelrods (between prisms )  Microtags - smaller tags formed at end of each rod where individual hydroxyapatite crystal has been dissolved. More important because of greater number and surface area. 20
  21. 21. Various etchants used – 1. Phosphoric acid – as liquid or gel. 2. Sulphuric acid 2 % 3. Citric acid 4. Maleicacid 10 % 5. Nitric acid2.5 % 6. Oxalicacid 21 Depth of decalcification is affected by– a)pH of the acid b)Concentrations c)Time
  22. 22. Micromorphologic Patterns of etching of Enamel A properly etched enamel surface gives a frosty white appearance on drying. Type1–Most common. Preferential removal of enamel prism cores & periphery intact. Type2-Reverse of type 1. Periphery removed andcores intact. Type3–Etching pattern less distinct. Both types 1 & 2 present. 22
  23. 23.  After etching, the enamel surface should be throughly rinsed with a continuous stream of water spray for 5-10 sec so that acid is completely washedoff. DRYING:  This should be followed by proper drying which will produce frosty, white appearance.  Contamination of the etched and dried enamel surface by saliva, moisture or bloodcanpreventproperbonding.  If anysortofcontaminationoccurs,repeat theprocedure. 23
  24. 24.  Generally, enamel bonding agents contain Bis-GMA or UDMA with TEGDMA added to lower the viscosity of the bonding agent.  Since, enamel can be kept dry, these hydrophobic resins worked well when they were confined only to enamel. 24
  25. 25.  Bonding to dentin has been proven more difficult and less reliable than to enamel.  This is basically because of difference in morphologic, histologic and compositionaldifferencesbetweenenamelanddentin. 25
  26. 26. PROBLEMS IN BONDINGTO DENTIN 1) It has considerable amount of organic material & water (30% organic material;20%fluid). 2) Random arrangement of hydroxyapatite crystals in the organic matrix. (They havea regularpatterninenamel). 3) Presenceofdentinalfluidwhichflowsoutward,adverselyaffectsbonding. 4) Scleroseddentinisdifficulttopenetrateasperitubulardentinbecomeswider. 5) Dentin contains dentinal tubules which contain vital processes of the odontoblasts. This makes the dentin a sensitive structure. 26
  27. 27. 6) Cut dentin surface is covered by smear layer, that fills the orifice of dental tubules, & blocks dentin permeability upto 86%. 6) Because of close proximity to pulp, various chemicals used for etching & dentin bonding may irritate the pulp. 7) It’s a dynamic tissue, that shows changes due to ageing, caries or restorative procedures. 27
  28. 28.  ETCHENTS/ CONDITIONERS  PRIMERS  ADHESIVES  FILLERS 28
  29. 29.  ORGANIC ACID:- Maleicacid,EDTA ,citric acid, tartaricacid.  INORGANIC ACID:- phosphoric acid, nitric acid.  POLYMERIC ACID:- poly acrylicacid 29
  30. 30. • HEMA:2-HydroxyethylMethacrylate • PENTA:DipentaErythritolPentaAcrylateMonoohosphate • NPG-GMA:N- PhenylGlycineGlucidylMetharylate 30
  31. 31.  Hydrophobicmonomers  BIS-GMA  UDMA  Diluent  TEGDMA  Wettingagent  HEMA 31
  32. 32. FILLERS Most of the bonding agents are unfilled. May contain inorganic fillers 0. 5% to 40% by wt. microfillers, or nanofillers,and submicron glass. Advantages of nanofillers: 1. Provides radio opacity. 2. Better dissipation of forces. 3. Scatter of light isprevented. 4. Causes uniform thicknessof adhesive layer. 5. Better flexibilityto adhesives. 32
  33. 33. CONDITIONING OF DENTIN Defined as removal or modification of the smear layer, to create a surface, capable of micromechanical and chemical bonding to dentin bonding agent. CHANGES AFTER CONDITIONING: Removal or modification of smear layer. Opening of dentinal tubule orifices. Exposesthe microporous collagen network. Decalcification of inorganic portion. 33
  34. 34. Conditioningcan be done by- A. Chemicals 1. Acids 2. Calciumchelators B. Thermal  Lasers C. Mechanical  Abrasion 34
  35. 35. CHEMICALS : 1. ACIDS: 1. Phosphoric acid 2. Sulphuric acid: [2 % for 30 sec.]  As effective as phosphoric acid. 3. Nitric acid: [2.5% ]  Stronger than H3PO4 4. Maleicacid:[10%]  Removes only smear layer, not plugs. 35
  36. 36. 4. Citricacid:  10% citricacid+ 3% FeCl3 was recommended by Nakabayashi.  Lately, Kuraray proposed a combination of 10% citric acid and 20% CaCl2 to stabilize collagen during etching. 5. Pyruvic acid: Pyruvic acid buffered with glycine is used to facilitate polymerization reactions and adjust the pH. 36
  37. 37. 6. Polyacrylicacid: [40%]  Recent product.  A 10 second application opens up the dentinal tubules but does not effect pulp as the particle size is greater than diameter of dentinal tubules. 7. Hydrochloric acid :  Causes violent surfacereactions. 37
  38. 38. 2. CALCIUM CHELATORS:  Chelators are used to remove the smear layer without decalcification of the underlying dentin as opposed to strong acid etchants. EDTA  Commercially availableas “Tublicid”.  It contains 0.1% EDTA and0.15% Benzalkonium chloride.  Removes smear layer, not plugs.  It is scrubbed on the surface of the smear layer for a few seconds, then left passivelyfor another 60 seconds followed by additional scrubbing. 38
  39. 39. B. THERMALCONDITIONERS LASERS  Nd:YAG laser used at 10 to 30 pulses per second.  The mechanism of action is through microscopic explosions caused by thermal currents.  The carbonized blackrot iseasily washed off with water. C. MECHANICAL CONDITIONERS ABRASION  Al2O3 is used for micro abrasion.  0.5 μparticles are used. 39
  40. 40. PRIMERS  Theseare adhesion-promoters.  Amphiphilic bifunctional molecules i.e have both hydrophillic and hydrophobicmonomergroups.  Hydrophillicbindsto:Dentin(exposedcollagenfibrils)  Hydrophobicbindsto:Adhesiveresin  The priming step converts the hydrophillic dentin into a hydrophobic and spongystateforpenetrationbytheadhesiveresin.  Theprimersare usuallydissolvedinacetone,ethanolorwater. 40
  41. 41.  These solvents are volatile and displace water (water chasing ability) from the dentinsurfaceandthemoistcollagennetwork.  This will allow the monomer of the primer to penetrate through the spaces in thecollagennetwork.  For proper penetration, it is preferred to keep the dentin surface moist, otherwise collagen fibers get collapsed in dry condition resisting the entry for primerandadhesiveresin.  Primingisdoneafter etching.It shouldbeappliedinmultiplecoats. 41
  42. 42. SOLVENTSUSEDINPRIMERS: 1) Acetonebasedprimers Advantages:  Excellentwater chaser. Disadvantages:  Evaporatesquicklyafter beingdispensed.  Canevaporatefromthecontainer,socanleadtochangeincomposition.  Multiplecoatsmay berequired.  Offensiveodour. Ex- Onestep PrimeandBondNT Glumaonebond. 42
  43. 43. 2. Ethanolbased primers Advantages : Evaporates less quickly Good surface energy and good penetration. Disadvantages : Extradrying time. Ex- Excite Optibond solo plus 43
  44. 44. 3. Water based primers – Advantages : Slow evaporation. Have capacityto raise collapsed fibers.(9%-50%) Disadvantages : Long drying time. Water caninterfere with adhesive if not removed. Ex- Amalgabond plus Prompt l pop Scotch bond multipurpose 44
  45. 45. COMBINATION OF THE SOLVENTS THAT CAN BEUSED AS PRIMERS 1. Acetone & H2O Eg: Tenure- quick 2. Acetone & ethanol Eg: All bond 2 (Bisco) 3. Ethanol& water Eg: Gluma comfort bond Scotchbond 45
  46. 46.  By etching dentin, the smear layer and minerals from it are removed, exposingthecollagenfibers(&demineralizeddentin).  Areasfromwheremineralsareremovedare filledwithwater.  This water acts as a plasticizer for collagen, keeping it in an expanded soft state.Thus,spacesforresininfiltrationare alsomaintained.  But these collagen fibers collapse when dry. This prevents the resin penetrationandhybridlayerformation. 46
  47. 47.  Water removal also might permit additional hydrogen bonds to form between collagen molecules, that previously were bonded to water molecules, leaving no interfibrillar space.  During air drying, the volume of collagen network decrease to one third of its original volume.  For this reason, presence of moist/wet dentin is needed to achieve successfuldentin bonding. 47
  48. 48.  Introduced by Dr. JohnKanaandGwinnetin 1992.  So, it refers to bonding in which acid etched dentin is moist and hence, acetone based primers are used.  acetone and ethanol based primer displace water and carry monomers in b/w exposed collagen fibres. The primer solvents are then evaporated by gentle air drying leaving the active primer monomer behind. 48
  49. 49.  To get moist dentin after etching, do not dry the dentin with compressed air after rinsing awayetchant.  Instead use high-volume evacuation to remove excess water and then blot the remaining water present on the dentin surface using gauze or cotton to leave dentin optimally moist.  Rewetting dentin after air drying to check for the enamel frosty aspect is an acceptable clinicalprocedure.  Rewetting can be done by 35% HEMA, Chlorhexidine. 49
  50. 50.  On rewetting, the collagen network assumes its original volume.  The re-expansion during rewetting occurs because the spaces between the fibres are refilled with water. Also, type I collagen itself is capable of undergoing expansion on rehydration.  Since water is lost gradually, the wet bonding technique has a better bonding ability thanthe dry bonding technique. 50
  51. 51. AZEOTROPHISM  In acetone containg primers, when acetone comes in contact with water, the boiling point of acetone is raised &the boiling point of water is lowered causingevaporation of both water and acetone and the resin is left behind. 51
  52. 52.  Refers to the bonding in which the acid etched dentin is dry and so water-based primersareused.  Water-based primers are not dependent on moist dentin because of their ability to self-wet a dried dentin surface and thus separating the collapsed collagen fibers.  NOTE: Studies show that moist dentin is friendly with all primer types, it is advisabletohavemoistdentinforresin-dentinbonding. 52
  53. 53.  Hybridoid region/ Ghost hybrid layer is that area of demineralized dentin into which resin fail to penetrate.  It is one of the disadvantages in dry bonding technique because of ineffective resin penetration due to collagen collapse  It appears if surface air dried for more than 3 sec.  This zone inside the hybrid layer do not appear electron dense on demineralized TEM sections.  Reduced bond strength. 53
  54. 54. OVER-WETTINGPHENOMENON:  If solvent of primer (acetone/ethanol) fails to remove water completely from dentin,Over-wettingphenomenonresults.  Excessivewater dilutesprimer-reduceeffectivenessofprimer.  Dentinal tubules are more prone to show this phenomenon than the intertubulardentinduetotheirhighwater content.  In this the solubility of monomers is lowered as the excess moisture lowers theconcentrationoforganicsolventsintheprimer.  Monomerispresentasglobulesover thewater layer. 54
  55. 55.  The dentin surface may appear blister like with water being trapped beneath the resin layer.  Since blisters gets compressed and causes flow of dentinal fluids, hence this leads to Post-operative sensitivity. 55
  56. 56. DISADVANTAGES OF WET BONDING TECHNIQUE 1. Technique sensitivity 2. Evaporation of acetone  Increased monomerratio  Decreasedpenetratiablity of monomers  To overcome this problem acetone based adhesive formulations are available in Pre- dosed-single patient use capsules (primerbond NTQuix ). 3. Difficult in checkingthe frosted appearance of enamel 56
  57. 57. ADVANTAGES OF DRYSURFACE 1. Frosted appearance of etched enamel can be verified. 2. Reduce risk of over wetting. (Rewetting of tooth surface using wet cotton pellet with water or chlorohexidine or 35% HEMA). 57
  58. 58. AIR DRIED MOIST OVERWET COLLAPSE OF COLLAGEN SWELLING OF COLLAGEN NO RESIN PENETRATION LESSER SPACE AVAILABLE FOR RESIN PENETRATION NO HYBRIDLAYER OPTIMAL HYBRIDLAYER 58 COLLAGEN MAINTAINED
  59. 59.  Ideally a dentin bonding agent should have both hydrophilic and hydrophobic ends. The hydrophilic end displaces the dentinal fluid, to wet thesurface.Thehydrophobicendbondstothecompositeresin. MECHANISM OF ACTION OF DENTIN BONDING AGENTS ___ ___ M R X HYDROPHILLIC/ COMBINESWITH ORGANIC& INORGANIC PORTIONOFDENTIN HYDROPHOBIC/ COMBINESWITH COMPOSITERESIN (METHACRYLATEGROUP) This is a spacergroup that provides flexibility &mobility to M group, after the X group has beenimmobilizes by reaction at a surface (tooth surface). Hence, it increases the reactivity. 59
  60. 60. X INORGANIC PART OF DENTINE[Ca IONS] ORGANIC PARTOF DENTIN 1. Amino(-NH) 2. Hydroxyl (-OH) 3. Carboxylate (-COOH) 4. Amide(-CONH) groups present indentinal collagen 1. Phosphate 2. Aminoacids 3. Aminoalcohol 4. Dicarboxylates 1. Isocyanates 2. aldehydes 3. carboxylic acid 4. Anhydrides 5. carboxylic acid chlorides •Theseremove hydrogen from the below groups and combine chemically. IONIC INTERRA CTION 60
  61. 61.  Whenever tooth surface is cut with hand or rotary instruments , it causes small particlesofthecuttoothsurfacetoadheretotoothproducingthesmear layer.  Smear layer is defined as any debris ,calcific in nature ,produced by reduction orinstrumentationofenamel,dentinorcementum.  The smear layer easily washedaway from the enamel, but remains adherent to thedentinsurface. 61
  62. 62.  It hastwocomponents: 1. Thesuperficialsmear layer. 2. Smear plugsthatoccludethedentinaltubules.  Opinionsdifferaboutthesmear layer.  Some researchers consider it a natural protective liner for the pulp, while others consider it as a source of microorganisms which can cause pulp irritation.  It interferes with adhesion, and so it should be removed, dissolved or modifiedbeforeapplyingdentinbondingagents. 62
  63. 63.  Zone where the adhesive resin of the dentin bonding agent micromechanically interlocks within the intertubular dentin and surrounding collagen fibres. Formed in the following manner: A) Etching removes the smear layer & minerals (hydroxyapatite) exposing the collagen fibrils & demineralized dentin. B) Primers penetrate collagen network & demineralized dentine. C) Along with the primers, adhesive resins form resin microtags within the intertubular dentin andsurround the collagen fibres upon curing. 63
  64. 64.  Whenabonding agentis applied,partofitpenetrates intothe collagennetwork, known as intertubular penetration and the rest of it penetrates into dentinal tubulescalledintratubularpenetration.  Intratubular penetration or the formation of resin tags upto a limited depth of 10-20microns.  GivenbyNakabayashiin1982. CHARACTERISTICFEATURESDUETO HYBRIDIZATION : 1) ShagCarpetAppearance 2) TubuleWallHybridization 3) Lateral tubuleHybridization 64
  65. 65. 1. Shag Carpet Appearance :  Appears when dentin surface after being acid etched is actively scrubbed with an acidicprimer solution.  The combined mechanical and chemical action of rubbing the acid etched dentin with an acidicprimer results in: 1. Additional mineral saltsare dissolved. 2. Fraying and separation of the entangled collagen at the surface occurs. 65
  66. 66. 2. Tubulewall hybridization:  Extensionof the hybrid layer into tubule wallarea.  Hermetically sealsthe pulpodentinal complex againstmicroleakage.  Specially 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. This is attributed to tubule wall hybridization which ensures aleakage free seal of tubules. 66
  67. 67. 3) Lateral Tubule Hybridization :  Formation of tiny hybrid layer into the wallsof lateraltubule branches.  This microversion of hybrid layer typically surrounds a central core of resin and calledmicroresin tag. 67
  68. 68.  After etching, silica remnants from the phosphoric acid present on the exposed collagen fibres, cannot be removedby vigorous rinsing.  These particles will not bond to infiltrating resin and hence, increase nanoleakage and lead to failure overtime.  These acid exposed non infiltrated collagen fibres undergo hydrolytic degradation when exposed to fluid for long periods.  Due to these limitations of the total etch technique, alternative dentin bonding strategies havebeenproposed, like self etch adhesives and deproteinization. 68
  69. 69.  Sodium hypochlorite is a non-specific proteolytic agent that effectively removes organiccompoundsatroomtemperature.  Thus, NaOC1 a deproteinising agent is used to completely remove the collagen layer.NaOCIapplicationwasperformedafteracidetchingandnotpriortoit.  SEM revealed the direct resin tag penetration into the underlying dentinal tubules(ReverseHybridlayer)withabsenceofa truehybridlayer.  The total absence of any resin infiltrated collagen layer, may prevent any hydrolytic degradation from taking place, thus accounting for the overall increase inbondstrengthvalues. 69
  70. 70.  Because of polymerization shrinkage, there is detachment of the adhesive resin fromtheunderlyinghybridlayer.  If a layer of separately polymerized adhesive resin[thickness of 50 – 100 μ, elastic unfilled or semi filled] is placed, below composite resin, a gap free intact surfacecanbefrequentlyobserved.  These act as a shock absorber by elastic elongation thereby preventing the interfacefromdetaching.  Superficial layers are unpolymerized which then provide double bonds to polymerize with the composite. 70
  71. 71. WATERTREES  Water can pass from dentin around resin tags & form water filled channels that project from the hybrid layer into the overlying adhesives.  When these water filled channels are stained with silver, they often look like microscopic trees.  These arecalled water trees by Tay & Pashley.  They suggested that they might act as potential sites for hydrolytic degradation of resin &also may bethe causeof nanoleakage.  All marketed products permitted someamount of water tree formation. 71
  72. 72. 1. According to generation. 2. According to adhesion strategy (number of clinicalapplications). 3. According to treatment of smear layer. 4. According to mode of curing. 5. According to pH. 6. According to bond strength. 72
  73. 73. CLASSIFICATIONBASED ONTHE NUMBEROFCLINICALAPPLICATONS STEPS AND HOW THEY INTERACTWITHTOOTHSTRCTURE 1) Total etch adhesives: 3 step 2 step 2) Self etch adhesives: 2 step 1 step 3)Resin modified glass ionomer adhesives 73
  74. 74. ON THE BASIS OFTREATMENT OFSMEAR LAYER 1) Removed: TenureM Mirage bond Clearfil liner bond system 2) Modified: All bond Scotch bond 2 XR Bond 3) Preserved: Scotch bond dual cure Prisma universal bond 74
  75. 75. ACCORDINGTOTHEIRMODE OF CURING 1) Chemical cure: Amalgabond plus 2) Light cure: One bond Gluma comfort bond 3) Dual cure: Clearfil liner bond 2V Prime and Bond NT dual cure. 75
  76. 76. C) DEPENDING ONTHE pH (VanMeerbecketal2003) 76 Mild ( pH ≥ 2 ) Cause hybridization + intermolecular bonding Intermediary strong ( pH of 1.5) Are more acidic than“ mild” adhesives, so achieve greater micromechanical interlocking at the enamel surface Strong ( pH ≤ 1 ) Hybridization + Nochemical reaction may take place, since the hydroxyapatite is entirely removed.
  77. 77.  Intermolecular bonding: Hydroxyapatite acts as a receptor for additional molecular interactions with specific carboxyl orphosphate groups of monomers like 4 META.  Examples: 1) Mild adhesives :  Clearfil SE  Panavia ED primer 2)Intermediary adhesives :  XenoIII  AdheSE primer  Optibond Solo Plus SE primer  I Bond 3)Strong adhesives : NRC Adper Prompt 77
  78. 78. ONTHE BASISOF SHEAR BOND STRENGTH(EICK etal) 1)5-7Mpa:  Scotchbonddualcure  Gluma 2)8-14Mpa  Tenure  Miragebond 3)17-20Mpa  Scotchbond2  Scotchbondmultipurpose  Allbond 78
  79. 79.  Developed in 1960s.  First generation adhesives started with the development of NPG-GMA (Comonomer).  It chelates with the Ca of the dentin and form a water –resistant chemical bond.  When nuclear magnetic resonance analysis was done, it was found that no ionic bond exist between NPG-GMA &hydroxyapatite(Ca).  Low bond strength (2–3 MPa).  Tradename: Cervident 79
  80. 80.  Developed in 1978.  Low bond strength (1–5 Mpa).  It consisted of a phospahate – ester material. -velycharged Binds to Ca of smear layer.  Ex:ClearfillBond System Scotch Bond Also the smear layer is loosely attached, so the bond created was not strong These were hydrophobic [So,do not wet dentin] Cannot penetrate to entire depth of smear layer Unable to reach superficial dentin for ionic bond 80
  81. 81.  Conceptwastomodifythesmearlayer,rather thanremoving.  Thisallowspenetrationofacidicmonomers.  For modification of smear layer, concept of phosphoric acid etching of dentin before applicationof aphosphateester-typebonding agentwas introducedby Fusayamaet alin1979.  Acid etching causes flow of resin into open dentinal tubules, even then any significant improvement in dentin bond strength was not found. This was becauseofthehydrophobicnatureofbondingresin. 81
  82. 82.  So, overall there is preservation of modified smear layer with slight demineralizationoftheunderlyingintertubulardentinsurface.  Acidsusedwere: 1. 2%nitricacid 2. 2.5%maleicacid 3. 10%citricacid 4. 10%phosphoricacid  Pulpalinflammatory responses were thoughtto be triggeredby application ofacid.  Ex:ClearfillNewBond ScotchBond2 82
  83. 83.  Based on removal of smearlayer to permitresin bonding to the underlying dentin.  Removal of smear layer via acid etching leads to significant improvement in bond strength.  Thethree essential components of this system are: 1. Etchant: Phosphoric acid gel. It is rinsed off 2. Primer: Hydrophillic monomers +Solvent [ethanol, acetone orwater] 3. Bonding agent resin: unfilled orfilled  Ex:ScotchBond Multipurpose Optibond All- Bond 2 83
  84. 84. PARTIAL/ TOTAL REMOVAL OF SMEAR LAYER ADHESION PROMOTER COPOLYMERIZE WITH PRIMED DENTIN & ALSO WITH COMPOSITE OVER IT EXPOSES COLLAGEN NETWORK DEMINERALIZ ATION OF UNDERLYING DENTIN (UPTO 7.5 Micro M)/ OPENS UP DENTINAL TUBULE Etchant Primer Adhesive 84
  85. 85.  As the technique involves simultaneous application of acid to enamel & dentin, this method is commonly k/s TOTAL ETCH TECHNIQUE / ETCH & RINSE TECHNIQUE / THREE STEP TOTAL ETCH SYSTEM.  Concept of HYBRID LAYER comes in this generation. 85
  86. 86.  This was done to reduce number of steps &soeasytouse.  As primer & bonding agent are combined into a single solution, they are also called “ONEBOTTLE”system. Etchant Primer + Adhesive 86
  87. 87.  Also known as NON RINSING CONDITIONER [NRC]/ SELF PRIMING ETCHANTS [SPE].  In contrast to conventional etchants, SEPs arenot rinsed off.  This reduces the possibility of overwetting & overdrying, both of which affects the adhesion adversely. ETCHANT + PRIMER Self etching primer [SEP] Adhesive Ex:Clearfil SE Bond 87
  88. 88. TYPE I SELF ETCH PRIMER & ADHESIVE  2 bottle system.  Components of both the bottles are applied separately. i.e self etch primer applied first followed by adhesive  Ex:Clearfil SE Bond  2 bottle system.  Components of both the bottles are first mixed & then applied.  Ex:Xeno III adper prompt TYPE II SELF ETCH ADHESIVE 88
  89. 89.  DISADVANTAGE: 1. SEPs do not etch enamel as well as phosphoric acid, & so do not provide higher bondstrength/betterclinicalperformancethanphosphoricacid. 2. Initial bond might deteriorate with ageing,which could leadto prematurefailures. 3. Bonding to sclerotic andcaries affected dentin might be problematic. ADVANTAGES: 1. Less technique sensitive than total –etch adhesive. 2. SEPs demineralize &infiltrate dentin simultaneously. So, they are less likely to cause discrepency between depth ofdemineralization & depth if infiltration. 89
  90. 90. SIMPLICITY Introduced by Dr. JohnKanca. Its film thickness is sufficiently thin, so can be used to bond posts to endodontically treated teeth and to bond indirect resin inlays. 90
  91. 91.  Ex:  Prompt LPop  Touch andBond  Brushand bond  Xeno III Etchant Primer Adhesive All in one adhesive 91
  92. 92.  Both the sixth and seventh generation adhesives are self etching, self priming adhesives, but the seventh generation bonding agents also have disinfecting and desensitizing properties.  Fluoride releasing.  Colour changing capacity (visual confirmation of complete curing).  Theseventh generation DBAs haveshown verylittle orno postoperative sensitivity.  Ex- G-Bond, iBond, XenoIV, Adper Easy Bond, AdheSE OneandClearfil S3Bond. 92
  93. 93. iBond Single step, no mix bonding system. Five in one solution: a) Etch b) Prime c) Bond d) Disinfect e) Desensitize 93
  94. 94. G-BOND  Based on nano interaction technology. Nanointeractiontechnology  G-BOND forms a non-conventional interface with the dentin “Nano Interaction Zone” (NIZ) with minimal decalcification and almost no exposure to collagen fibers.  This “nano” level reaction produces an insoluble calcium compound for a better bond less likelyto deteriorate.  Creates a remarkably thin (less than300 um) bonding layer .  Completely coats allbonding surfaces with very few voids. 94
  95. 95. EIGHTGENERATION  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 separate bonding application step with composites for direct restorative procedures.  In this there is a stablenanofiller that willnot settle out of dispersion.  Ex-Vertise flow (Kerr), Single Bond, Optic Bond Solo Plus, Adper Single Bond 2 adhesive 95
  96. 96. CLINICALINDICATIONS OFDENTINBONDINGAGENTS: 1. Bondingofdirectlyplacedresinbasedrestorativematerials. 2. Bondingofindirectlyplacedrestorativematerials. 3. Bondingofceramicrestorations. 4. Bondingofamalgam restorations. 5. Repairexistingrestorations. 6. Treatmentofcervicalabrasion. 7. Bondingofprefabricatedandcastposts. 8. Sealingofpitsandfissuresofposteriorteeth. 9. Reattachmentoffracturedtoothfragments. 10. Reinforcefragilerootsinternally. 11. Bondingorthodonticbrackets. 12. Bondingperiodontalsplints. 96 CONTRAINDICATION Dentin bonding agents should not be used if the patient isknown to be allergic to any of the ingredients used.
  97. 97. SIDE EFFECTS 1) Sensitizing reaction (burning sensation) : Seen in patient with a hypersensitivity to any of its ingredients. Its treatment is that the material should be removed. 2) Gingival Tissue reaction : It is white in appearance ,but not painful, has been reported after extended contact with these materials. The reaction ceases within few days. INTERACTIONS Materials containing Eugenol or Clove oil inhibits the polymerization of DBA. These types of materials should not be used in conjunction with DBA. 97
  98. 98. CLINICAL SUCCESS OR FAILURES IN BONDING :  Can occur at various levels: 1. Between mineralized anddemineralized dentin. 2. Between demineralized dentin andbonding agent. 3. Within layer of bonding agent. 4. Between bonding agent and composite resin.  Factors affecting it are as follows: 1. Size And Shape Of Lesion:  Small sized cervical lesions show less adhesion as compared to deep, wedge shaped lesions 98
  99. 99. 2)Archtype:  Adhesion is better in case of maxillary arch than mandibular arch due to lesserchancesofmoisturecontamination. 3)Age:  With increasing age dentin gets sclerosed and thus adhesives show a greater failurerate.  Apart from old age, the age of lesion and the time period for which dentin wasexposedalsoplayanimportantroleinadhesion. 4)Dentinwetness:  Higher the wettability of bonding agents, higher will be the permeability / penetration.It ensuressuccessfulbonding. 99
  100. 100. REFERENCES: 1) Sturdevant’sArt AndScienceOfOperativeDentistry,5th Edition. 2) Phillip’sScienceOfDentalMaterials,11th Edition. 3) TextbookOf OperativeDentistry,VimalSikri,2nd Edition 4) Article-TheProgressionOfDentalAdhesives(Www.Ineedce.Com) 5) Article – Newer Is Not Always Better, Inside Dentistry, March 2012, Part 1 AndPart2 6) Article–SelfEtchingAgents,TheDentalAdvisor 7) FundamentalsOf OperativeDentistry2nd Edition-jamesB.Summitt 8) ToothColouredRestorations- Alber’s 9) TextbookOfOperativeDentistry-SatishChandra,ShaleenChandra 10) DentalMaterials,8th Edition,Craig’s 11) InternetSourcesForImages 100
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