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Adhesives
- 1. ADHESIVESADHESIVES Dr. Fazal ur Rehman Qazi BDS,FCPS Asst. Prof. Operative Dentistry DIKIOHS
- 3. 3 Principles of AdhesionPrinciples of Adhesion Clean surfaces Closely approximating surfaces Maximum surface area of contact Good surface wetting by the adhesive Stable over long-term
- 4. Requirements for BondingRequirements for Bonding + >Mechanical Adhesion Chemical Adhesion Stress over Bond Lifetime •Enamel, Dentin •All areas of the bond •Stresses: residual (shrinkage) thermocycling occlusion mastication •Chem / Bio environment • Surface area • Penetration of resin • Undercuts • Cured adhesive strength •Ionic bonds •Metallic bonds •Covalent bonds •Dipole interactions •Van der Waals
- 5. Mechanical Adhesion Etching Priming Bonding Dentistry VELCRO (Hook and Loop Fastener)
- 6. 6 Structure of DentinStructure of Dentin Erosion Translucent Dentine Inner Occlusal Dentine Outer Occlusal Dentine PULP Multizoned Carious Lesion Reactive Dentine (erosion, abrasion) Physiologic Dentine (aging, wear) -many occluded tubules 4% vol 28% vol Heymann & Bayne 1993
- 7. Cavity edge Axial wall Cementum Gingival floor 7 >50% Class V & II cavity surfaces had oblique or parallel cut dentine tubule orientations DIRECTION OF DENTINAL TUBULES
- 8. 8 Direction of Tubules and Prisms Potential for poor bonding to dentine at gingival floors Dentine tubulesDentine tubules Hybrid layerHybrid layer MicroleakageMicroleakage End on (90End on (90ºº)) 30-35 µm + tags30-35 µm + tags Signif. lowerSignif. lower Parallel cutParallel cut 1-10 µm + few tags1-10 µm + few tags Signif. higherSignif. higher
- 9. 9 Moisture on Exposed Dentine Sources: Oral humidity Saliva Triple syringe Dentine tubules
- 10. 10 The Smear LayerThe Smear Layer ~1-5 µm Bond strength to tooth structure ~2-5 Mpa Can be altered or removed
- 11. 11 Hybrid Layer Formation in Dentine ETCHANTPRIMER ADHESIVE RESIN Intertubular Dentine Peritubular Dentine Dentinal Tubules Hybrid Zone Collagen
- 12. FRQ 1960 1970 1980 1990 2000 2010 1st / 2nd Generation Only bond to enamel, pH neutral 3rd Gen. pH < 7 3-step Etch&Rinse 2-step Etch&Rinse 2-step Self-etch 1-step Self-etch 1989: Hybrid layer Dental Adhesives History Enamel Etch Concept – Buonocore 1955 N-Phenyl-Glycin-Glycidyl-Methacrylate Bowen 1965 1983 Scotchbond / 3M Bis-GMA-PO4-ester 1988 Scotchbond 2 / 3M Maleic acid/HEMA 1973 Concise Enamel Bond / 3M
- 13. 1960 1970 1980 1990 2000 2010 1th / 2th Generation No etching, pH-neutral 3th Gen. pH < 7 3-step Etch&Rinse 2-step Etch&Rinse 2-step Self-etch 1-step Self-etch 1989: Hybridlayer Dental Adhesives History N-Phenyl-Glycin-Glycidyl-Methacrylate Bowen 1965 1983 Scotchbond / 3M Bis-GMA-PO4-ester 1988 Scotchbond 2 / 3M Maleic acid/HEMA
- 14. 1960 1970 1980 1990 2000 2010 1th / 2th Generation No etching, pH-neutral 3th Gen. pH < 7 4th Gen. Etch&Rinse 5th Gen. Etch&Rinse 6th Gen. Self-etch 7th Gen. Self-etch 1989: Hybridlayer Dental Adhesives History N-Phenyl-Glycin-Glycidyl-Methacrylate Bowen 1965
- 15. 1960 1970 1980 1990 2000 2010 1th / 2th Generation No etching, pH-neutral 3th Gen. pH < 7 3-step Etch&Rinse 5th Gen. Etch&Rinse 6th Gen. Self-etch 7th Gen. Self-etch 1989: Hybridlayer Dental Adhesives History N-Phenyl-Glycin-Glycidyl-Methacrylate Bowen 1965
- 16. 1960 1970 1980 1990 2000 2010 1th / 2th Generation No etching, pH-neutral 3th Gen. pH < 7 3-step Etch&Rinse 2-step Etch&Rinse 6th Gen. Self-etch 7th Gen. Self-etch 1989: Hybridlayer Dental Adhesives History N-Phenyl-Glycin-Glycidyl-Methacrylate Bowen 1965
- 17. 1960 1970 1980 1990 2000 2010 1th / 2th Generation No etching, pH-neutral 3th Gen. pH < 7 3-step Etch&Rinse 2-step Etch&Rinse 2-step Self-etch 7th Gen. Self-etch 1989: Hybridlayer Dental Adhesives History N-Phenyl-Glycin-Glycidyl-Methacrylate Bowen 1965
- 18. 1960 1970 1980 1990 2000 2010 1th / 2th Generation No etching, pH-neutral 3th Gen. pH < 7 3-step Etch&Rinse 2-step Etch&Rinse 2-step Self-etch 1-step Self-etch 1989: Hybridlayer Dental Adhesives History N-Phenyl-Glycin-Glycidyl-Methacrylate Bowen 1965
- 19. 1990 2000 2010 3-step Etch&Rinse 2-step Etch&Rinse 2-step Self-etch 1-step Self-etch 1989: Hybridlayer Dental Adhesives Generations
- 20. FRQ
- 21. FRQ Tooth composition Enamel (wt%) Dentin (wt%) Minerals 97 % 70 % Organic 1 % 20 % Water 1 % 10 %
- 22. FRQ -Straight forward bonding -Strong acids etch very well -Surface can be dry -Resin flows in spaces -Polymerizes forming strong bond Bonding to Enamel Etch enamel with 35% phosphoric acid Enamel etch pattern
- 23. FRQ Bonding Mechanism to Dentin 1st, 2nd generation: only bond to etched enamel, bond to dentin best achieved by sandwich technique with glass ionomer base 3rd generation: weakly acidic primers partially dissolve the smear layer and etch dentin – low bond strength due to inadequate resin systems
- 24. FRQ Bond to Dentin – the Hybrid Layer e.g. 4th Generation Bonding Primer Resin tags Composite
- 25. FRQ The Hybrid Layer Demineralized, resin-impregnated dentin Concept established by Nakabayashi (1980s) TEM visualization techniques by Yoshida and van Meerbeek (1998) A – glass filled adhesive resin (Optibond FL) H – hybrid layer T – dentin tubule R – resin tag I – nondemineralized intertubular dentin B. van Meerbeek et al., J. Dent. Res. 1998 2 µm
- 26. FRQ Etching enamel and dentin (total etch) Hydrophilic primer wets and penetrates dentin very well Hydrophobic bond Introduced around 1993 First adhesives with high dentin bond strength Gold standards (Optibond FL, Scotchbond Multipurpose) 4th Generation Adhesives 44thth GenerationGeneration A B Etch Prime Bond
- 27. FRQ Etching enamel and dentin (total etch) Hydrophilic primer and hydrophobic bond of 4th generation combined into one bottle Introduced around 1997 Most popular adhesives in many parts of the world Examples: Prime&Bond NT, Optibond Solo Plus, Singlebond 2 5th Generation Adhesives 55thth GenerationGeneration Etch Prime + Bond
- 28. FRQ 5th Generation Adhesives Advantages: Less steps compared to 4th generation Long clinical history of over 10 years Disadvantages: Highest incidence of post-operative sensitivities Higher technique sensitivity moisture of etched dentin thickness of adhesive layer phase separation Loss of dentin bond strength over time
- 29. FRQ Etched dentin Bur Cut dentin with smear layer -More complicated bonding -Acids demineralize and open tubules -Surface is hydrophilic and must be kept moist -Requires priming -Must be completely sealed to prevent sensitivity Etched Dentin and Post-operative Sensitivity
- 30. FRQ Smear Layer after Cavity Preparation Cavity preparation produces smear layer Smear plugs close orifices of dentin tubules
- 31. FRQ Etching opens Dentin Tubules Etching with phosphoric acid (and also strong self-etch adhesives with pH <2) remove smear plugs Open tubules (etched bovine dentin): smear layer is removed Adhesive needs to close open tubules completely!
- 33. FRQ WET DRY MOIST Right Surface Moisture An Issue with Total Etch Adhesives…
- 34. FRQ Dull dentin appearance indicates dehydration What happens if the tooth surface is overdried?What happens if the tooth surface is overdried? The collapsed collagen decreases porosity and reduces adhesive absorption : Increases chance for sensitivity
- 35. FRQ The tooth surface needs to be moist!The tooth surface needs to be moist! Expanded collagen is porous and will absorb adhesive: minimizes post-op sensitivity.
- 36. FRQ „Phantom“ Hybrid Layer Perdigao, 1995 Overetched, overdried dentin Adhesive resin Uninfiltrated, collapsed collagen (removed by NaOCl) Resin tags in non- demineralized dentin
- 37. FRQ Consequences of Over-Drying Collapse of collagen network Incomplete infiltration and seal of the etched dentin Fluid movement within collagen leads to post-operative sensitivities Lower bond strength No protection of the exposed collagen against degradation Endogenic enzymes (matrix metalloproteinases / MMPs) are liberated and activated during etching step MMPs are active in incompletely infiltrated dentin and lead to significant loss of dentin bond strength over a few months
- 38. FRQ How to Minimize POS with 5th Generation Adhesives Isolation with Rubber Dam to prevent contamination Use an RMGI as liner / base (e.g. Vitrebond), especially in deep cavities Do not over etch dentin – apply etchant to enamel first, then dentin Thoroughly rinse off etching gel Keep dentin moist after etching – do not dry with air, but rather blot excess moisture Apply adhesive immediately after blotting Apply adhesive generously – 2-3 coats Do not air thin too aggressively – if all adhesive is blown away, there is nothing to bond to Continue immediately with filling composite
- 39. FRQ Self-Etch Adhesives (6th and 7th Gen) Acidic monomers in formulation to provide etch pattern for retention and chemical bond (eg MDP, 4-META) Introduced around 2000 (6th Generation, eg Clearfil SE Bond, first version of Prompt L-Pop) Mild SE adhesives (pH >2) / Strong SE adhesives (pH <2) Successful in USA, Japan, Western Europe Ease of use Low incidence of post-operative sensitivity
- 40. FRQ Acidic, hydrophilic primer Hydrophobic bond (eg Clearfil SE Bond) or Acidic resin and aqueous phase have to be mixed before application (eg Xeno III, Adper Prompt L-Pop) 6th Generation Self-Etch Adhesives A Etch + Prime Bond 66thth GenerationGeneration B
- 41. FRQ 7th Generation Self-Etch Adhesives All components combined into one bottle Usually „mild – ultra-mild“ (pH > 2) Fastest growing segment in adhesives market Intensely researched, but limited clinical evidence available Etch + Prime + Bond 77thth GenerationGeneration
- 42. FRQ Low POS with Self-Etch Adhesives First version of Prompt L-Pop 0% 2% 4% 6% 8% 10% 12% 14% 16% 18% 20% Prompt Prime&Bond NT 1 month 6 month *Note: Data pertains to clinical study on original Prompt formulation. U Iowa; Denehy et al. %Sensitive
- 43. FRQ Total number of dentists Number of dentists encountering post-operative sensitivity Total number of post-operative sensitivities Total number of restorations placed Percentage of restorations with post-operative sensitivity 100 7 26 5572 0.5% Low POS with Self-Etch Adhesives Adper Easy Bond Application test 3M ESPE internal data
- 44. FRQ Why do Self-Etch Adhesives reduce Post-Operative Sensitivity? No separate etching step – minimized danger of overetching and desiccation of dentin Resin penetrates as far as demineralization of dentin – minimized danger of unimpregnated collagen layer under adhesive
- 45. FRQ Self etch 2 steps Demineralization Resin penetration Risk of nanovoids Demineralization resin penetration + - 2 consecutive steps - risk of nanovoids, if penetration depth of etchant and resin are not equal - higher risk of post-op sensitivity - 1 single step - no risk of nanoleakage, since penetration depths are equal - lower risk of post-op sensitivity Adper Easy One
- 46. FRQ Why do Self-Etch Adhesives reduce Post-Operative Sensitivity? No separate etching step – minimized danger of overetching and desiccation of dentin Resin penetrates as far as demineralization of dentin – minimized danger of unimpregnated collagen layer under adhesive Adhesive is neutralized by basic hydroxyapatite during application
- 47. FRQ Why do Self-Etch Adhesives reduce Post-Operative Sensitivity? No separate etching step – minimized danger of overetching and desiccation of dentin Resin penetrates as far as demineralization of dentin – minimized danger of unimpregnated collagen layer under adhesive Adhesive is neutralized by basic hydroxyapatite during application Mild self-etch adhesives do not dissolve smear layer completely – most tubules remain protected by smear plugs
- 48. FRQ 7th Generation adhesive on dentin lab-demineralized dentin particle-filled adhesive Clearfil Protect LinerClearfil Protect Liner acid-resistant submicron hybridacid-resistant submicron hybrid layerlayer dentin tubuledentin tubule smear plugsmear plug TEM image courtesy of Prof. van Meerbeek, Univ. Leuven, Belgium
- 49. FRQ What the Scientific World says... First glance: MassesMasses Converting and usingConverting and using Self-EtchSelf-Etch AdhesivesAdhesives OpinionOpinion LeadersLeaders Supporting Total-EtchSupporting Total-Etch Adhesives – evenAdhesives – even 4th4th
- 50. FRQ Van Meerbeek et al. 2009, Dental Materials
- 51. FRQ “3-step etch&rinse adhesives and (mild) 2-step self-etch adhesives are still the benchmarks When bonding to enamel, an etch&rinse approach is definitely preferred When bonding to dentin, a mild self-etch approach is superior, as it involves (like with glass-ionomers) additional ionic bonding Altogether, … selective etching of enamel followed by the application of the 2-step self-etch adhesive to both enamel and dentin currently appears the best choice“ Van Meerbeek et al. 2009 Conclusions
- 54. FRQ Bond Strengths Bart van Meerbeek et al „Relationship between Bond-strength tests and Clinical Outcomes“ Dent Materials, 2009, 11, 148ff. “A good correlation (…) was found between the annual failure rates reported in the systematic review of Peumans et al and the “Battle of the Bonds” shear-bond strength data from Degrange et al.” „The significantly highest bond strength was measured for OptiBond FL (Kerr) that somewhat surprisingly performed not significantly better than the relatively new 1-step adhesive Easy Bond (3M ESPE).“
- 55. FRQ Adper Easy Bond 3M ESPE Development Objectives A new self-etch formulation Fast and easy to use Robust application Moisture tolerant +++++
- 56. FRQ Adper™ Easy One Self Etch Application
- 57. FRQ Adper™ Easy One Self Etch Application
- 58. FRQ Apply adhesive to tooth surface for a total of 20 sec Adper™ Easy One Self Etch Application
- 59. FRQ Gentle agitation of adhesive maximizes penetration into etched dentin and enhances integrity of hybrid layer leading to better bonds and less sensitivity. Adper™ Easy One Self Etch Application
- 60. FRQ Dry for 5 sec Adper™ Easy One Self Etch Application
- 61. FRQ Light cure for 10 sec Adper™ Easy One Self Etch Application
- 62. FRQ Adper™ Easy One Self Etch Application
- 63. FRQ TEM-Interface Analysis Dentin (self-etch) - Prof. van Meerbeek
- 64. FRQ TEM-Interface Analysis Cut Enamel (self-etch) - Prof. van Meerbeek
- 65. FRQ The Formulation Meeting of the Generations Adper Easy Bond HEMA Bis-GMA Dimethacrylate Vitrebond™ Copolymer Filler Ethanol Water Initiators Methacrylated phosphoric esters Adper Single Bond 2 HEMA Bis-GMA Dimethacrylate Vitrebond™ Copolymer Filler Ethanol Water Initiators pH = 2.7pH = 4.7
- 66. FRQ
- 67. THANKYO U!
Notes de l'éditeur
- Coming to the bond strength topic…
- These principles of adhesion are often cited in texts and journal articles. Although these key points are simple to list, adhesion to tooth structure is far from simple. If it were simple then the ideal adhesive system would have been invented. The truth of the matter is that there is no ideal adhesive system. We can have some degree of success however if we use the existing systems correctly.
- Going back in history , adhesive dentistry started somewhere in 1965 with the first attempts to bond to dentin. The first acidic fomulation and bonding agent in North America came with the introduction of Scotchbond in 1983….
- Going back in history , adhesive dentistry started somewhere in 1965 with the first attempts to bond to dentin. The first acidic fomulation and bonding agent in North America came with the introduction of Scotchbond in 1983….
- Going back in history , adhesive dentistry started somewhere in 1965 with the first attempts to bond to dentin. The first acidic fomulation and bonding agent in North America came with the introduction of Scotchbond in 1983….
- Going back in history , adhesive dentistry started somewhere in 1965 with the first attempts to bond to dentin. The first acidic fomulation and bonding agent in North America came with the introduction of Scotchbond in 1983….
- Going back in history , adhesive dentistry started somewhere in 1965 with the first attempts to bond to dentin. The first acidic fomulation and bonding agent in North America came with the introduction of Scotchbond in 1983….
- Going back in history , adhesive dentistry started somewhere in 1965 with the first attempts to bond to dentin. The first acidic fomulation and bonding agent in North America came with the introduction of Scotchbond in 1983….
- Going back in history , adhesive dentistry started somewhere in 1965 with the first attempts to bond to dentin. The first acidic fomulation and bonding agent in North America came with the introduction of Scotchbond in 1983….
- Going back in history , adhesive dentistry started somewhere in 1965 with the first attempts to bond to dentin. The first acidic fomulation and bonding agent in North America came with the introduction of Scotchbond in 1983….
- Enamel Considerations: Has been understood and consistent for years, and is the easiest to attain with proper etching. Exposed enamel prisms (honeycomb look) filled with resin and polymerized offer excellent retention. Critical bonding needs to be done to enamel, because bonding to enamel is the foundation for a successful, long-term restoration.
- Dentin Considerations: SEM shows dentin with the smear layer present and etched away. Many variables challenge the bond ability such as moisture, dryness, smear layer, caries, size of dentinal tubules, amount of collagen fibers, dentin quality, etc. . .
- When speaking about total-etch or 5th generation adhesives, what dreaded word comes to mind if they are used improperly: sensitivity. Why is this the case? How many of you have wrestled with the moisture issue in bonding situations? How moist is moist? How wet is wet? How dry is dry? Getting the right surface moisture is a critical element in past and present adhesive systems. Remember, once the dentin surface is etched, probably the most critical factor for high bond strength attainment pertains to the surface moisture of the tooth. The primary concern is that we do not over-dry the tooth nor keep excess moisture on the tooth. Wet – If excess, pooled water remains on the surface of dentin or enamel, it may dilute primer or adhesive and inhibit infiltration into the tooth, resulting in low bond strengths. Dry – If we bond to enamel alone, it’s ok to dry the surface off completely. But, when bonding to dentin, drying the dentin will significantly reduce your bond strength and cause sensitivity for the patient. Therefore it is important to maintain a moist bonding surface. Now lets take a look at the SEM photographs above. In a dry field (upper right) notice the lack of collagen fiber compared to the collagen fiber present in the moist field (lower middle). The collagen layers must be present and available for the adhesive to infiltrate in order to get a bond in all of the areas between the tubules.
- So what happens when the tooth surface is overdryed…(read bottom sentence)
- The tooth surface needs to be moist so the collagen fibers can accept the adhesive and incorporate into the success of the restoration. This technique will minimize sensitivity, but what else can be done…
- In a clinical field trial 100 dentists placed more than 5500 restorations. Adper Easy Bond showed only 0.5% of postoperative sensitivity which is significantly lower compared to most etch&rinse adhesives.
- Coming to the bond strength topic…
- In terms of bond strengths again Prof van Meerbeek is making a reference in his Dental Materails paper…
- We had some specific development objectives for Adper Easy Bond. First of all, a new self-etch formulation which you will later see is significantly different to the Prompt L-Pop formulation…
- The application protocol is as easy as it gets. Simply apply and scrub 1 coat of Adper Easy Bond for 20 seconds on dentin and enamel and air-dry the layer for 5 seconds. After light-curing for 10 seconds you are done….
- The marginal quality was investigated by Prof van Meerbeek by TEM. On dentin it shows a nice uniform hybrid layer which is quite thin…
- …and on enamel again a tight contact without voids or defects.
- Adper Easy Bond´s formulation is based on the long-time successful Adper Single Bond 2 formulation or in other words it is a real derivative….