new dba-1(1).pptx DENTIN BONDING AGENTS GENERATIONS, ADVANTAGES N DISADVANTAGES

DENTIN BONDING AGENTS

1. DENTIN BONDING AGENT PRESENTED BY DR. DRASTI SHRIVASTAVA

2. CONTENT 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. Introduction 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. Introduction 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. History of dentinal bonding 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. Clinical uses 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. adhesion 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

12. Requirements of adhesion

13. Wetting 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. CONTACT ANGLE 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

16. 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.

17. Hybrid Layer An intermediate layer of resin, collagen, and dentin produced by acid etching of dentin and resin infiltration into the conditioned dentin

18. Adhesion by hybrid zone/ layer 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.

19. Mechanism of bonding 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

20. In dentistry, bonding of resin to tooth surface is a result of four possible mechanisms: Mechanism of bonding Mechanical Adsorption Diffusion A combination of the above three mechanisms

21. Bonding of enamel . 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

22. BY ACID ETCHING- Increase micro mechanical bond increase surface energy ACID – ETCHING TECHNIQUE-- 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

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

24. Enamel Bonding Agents 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.

25. 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.

26. Dentine and enamel resin adhesion

27. 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

28. ETCH PATTERN 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.

29. 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.

30. Fig. 10.5 A,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.

31. Enamel etching patterns

32. 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.

33. Enamel etching patterns

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

35. Monomer penetration MECHANISM OF DENTINE BONDING Monomer polymerisation And collagen entanglement

36. 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

37. HYBRIDIZATION OF DENTIN C oncept 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.

38. Hybrid Layer An intermediate layer of resin, collagen, and dentin produced by acid etching of dentin and resin infiltration into the conditioned dentin

39. Adhesion by hybrid zone/ layer 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.

40. 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.

41. 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.

42. 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. Intertubular dentin Resin tag Hybrid layer Adhesive resin

43. 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

44. 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.

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

46. 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 . Smear layer

47. 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

48. 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

49. 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

50. DENTIN BONDING AGENTS CLASSIFICATION

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

52. 1 st Generation DBA NPG-GMA chelate with calcium in dentin=water-resistant chemical bond Example: Cervident (SS Whitte ) Low bond strength: 2-3 MPa 1 ST Gen Early 1950s NPG-GMA High poly shrinkage & thermal expan Cervident

53. 2 nd 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 2 ND 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)

54. 3 rd Generation DBA Modification/Removal of Smear Layer Steps:- Application of dentin conditioner (HEMA + Maleic /nitric acid) Application of the primer Application of the adhesive (unfilled resin) 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 3 RD Gen Mid 1980s HEMA, 2% aqueous nitric acid 4 Steps: cond , prim, adhesive, comp. Smear layer removal Scotch bond 2

55. 4 th Generation DBA ACID: 7.5 Micrometers Demineralization PRIMER: Increases the surface energy of the Substrate.(NPG GMA, BPDM) UNFILLED RESINS 40%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 1 ST Gen Early 1950s NPG-GMA High poly shrinkage & thermal expan Cervident

56. 5 th G eneration 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 5 TH Gen Mid to late 1900s Simplified version of 4 th Gen Two step system Single bond, one step

57. 5 th G eneration 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 5 TH Gen Mid to late 1900s Simplified version of 4 th Gen Two step system Single bond, one step Moist bonding technique

58. 6 th G eneration DBA Dissolution of smear layer and HA by methacrylated phosphate Dissolved components bound into polymerised matrix Solvent evaporates 6 TH Gen Early 2000s Phenyl P, HEMA I: self etching primers II: All in one Clearfill SF bond

59. 6 th G eneration DBA TYPE I TWO STEP/ NON RINSING CONDITIONER/ SELF ETCH PRIMER SYSTEMS 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. 6 TH Gen Early 2000s Phenyl P, HEMA I: self etching primers II: All in one Clearfill SF bond

60. 6 th G eneration DBA Type II 6 th Generation Bonding agent :One step/ Self etching adhesives/ All in one 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. 6 TH Gen Early 2000s Phenyl P, HEMA I: self etching primers II: All in one Clearfill SF bond

61. 7 th G eneration DBA iBond ( Heraeus Kulzer ) Single step no mix bonding system Five in one solution: Etch Disinfect Desensitize Prime and Bond 7 TH Gen Late 2002-Early 2005 Desensitizing agent added More prone to phase separation I-bond, G-bond

62. 7 th G eneration DBA GC s G bond 4 MET monomer :strong consistent bond to dentin Phosphoric acid ester monomer : Consistent bond to enamel. 7 TH Gen Late 2002-Early 2005 Desensitizing agent added More prone to phase separation I-bond, G-bond