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Dentin bonding agents final/cosmetic dentistry courses

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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
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Dentin bonding agents final/cosmetic dentistry courses

  1. 1. >> 0 >> 1 >> 2 >> 3 >> 4 >> INDIAN DENTAL ACADEMY Leader in continuing Dental Education
  2. 2. >> 0 >> 1 >> 2 >> 3 >> 4 >>
  3. 3. >> 0 >> 1 >> 2 >> 3 >> 4 >>
  4. 4. >> 0 >> 1 >> 2 >> 3 >> 4 >> Definitions • Adhesion ~ the attraction between two atoms and molecules at the contacting surfaces of different materials; it can be chemical (ionic), physical (van der Waals’), and/or mechanical (micro- or macro- interlocking) • Adhesive ~ monomer (or related) that penetrates and establishes intimate contact with the conditioned tissue substrate, polymerises, and forms a strong bond between such substrate and the restorative material • Priming ~ cleaning, structural alteration, and increasing adhesiveness of the substrate.
  5. 5. >> 0 >> 1 >> 2 >> 3 >> 4 >> • Etching ~ dissolution of the substrate, removed by rinsing to enhance intimate contact of adhesives with collagen. • Wetting ~ the ability of a liquid to come into intimate contact with solid substrate; facilitates bonding
  6. 6. >> 0 >> 1 >> 2 >> 3 >> 4 >> Evolution of the concept of “Acid etching”:
  7. 7. >> 0 >> 1 >> 2 >> 3 >> 4 >> Microstructure of enamel: % by volume 3% 12% 85% water organic mineral • Inorganic component is homogenous, regular rods and prisms
  8. 8. >> 0 >> 1 >> 2 >> 3 >> 4 >> Adhesion to enamel: • Acid etching removes approx 10 microns of enamel • Creates microporous layer 5-50 microns
  9. 9. >> 0 >> 1 >> 2 >> 3 >> 4 >> Microstructure of dentin: • Human dentin is a heterogenous material composed of a solid (circumpulpal) phase surrounding a network of tubules. • These tubules, measuring about 1 to 3 micrometer in diameter, contain elongated cell bodies that radiate from the the dental pulp organ throughout the entire dentin. • Their average density is about 30 000 tubules/square mm..
  10. 10. >> 0 >> 1 >> 2 >> 3 >> 4 >> Microstructure of dentin: • Structurally dentin is composed of mineral crystals deposited between a network of protein fibrils. • Approximately 90% of this network is type I collagen, the balance consisting of a sheath of phosphoproteins surrounding the collagen, and other proteins in small amounts.
  11. 11. >> 0 >> 1 >> 2 >> 3 >> 4 >> Microstructure of dentin: % by volume 22%33% 45% water organic mineral • Inorganic component is heterogeneous, peritubular and intertubular dentin • Low surface free energy - wets less easily
  12. 12. >> 0 >> 1 >> 2 >> 3 >> 4 >> A, Peritubular dentin; B, Intertubular dentin; C, Dentinal tubule
  13. 13. >> 0 >> 1 >> 2 >> 3 >> 4 >> A, Intertubular dentin; B, Peritubular dentin; C, Dentinal tubule
  14. 14. >> 0 >> 1 >> 2 >> 3 >> 4 >> Dentinal tubules Pulp DEJ • Diameter (microns) 2.5 0.8 • Number 45,000 20,000 • Tubular surface area 25% 3%
  15. 15. >> 0 >> 1 >> 2 >> 3 >> 4 >> Difficulties of bonding to dentin • Complex histologic structure and variable composition of the dentin. • Whereas enamel is 92% inorganic hydroxyapatite by volume, dentine is (on average) only 45% inorganic. • Also dentinal hydroxyapatite is randomly arranged in an organic matrix that consists primarily of collagen, which is permeated throughout by tubules. • These contain vital processes of the pulp odontoblasts. Hence, vital dentine is a sensitive structure. • The high water content provides competition with any adhesive biomaterial for bonding to dentine.
  16. 16. >> 0 >> 1 >> 2 >> 3 >> 4 >> Smear Layer: • Tooth surface instrumented with a rotary or manual instrument • Composed of: – Pulverized hydroxyapatite – Altered collagen – Bacteria – Saliva
  17. 17. >> 0 >> 1 >> 2 >> 3 >> 4 >> Smear Layer • To achieve a strong bond, it is necessary to either strengthen this smear-layer in situ or to remove it entirely. • In the latter, it is imperative to ensure an adequately adhesive restorative otherwise the open tubules may allow irritants or bacteria greater access to the pulp.
  18. 18. >> 0 >> 1 >> 2 >> 3 >> 4 >> Conditioning of dentin: • Removes smear layer. • Exposes a microporous scaffold of collagen fibrils increasing the microporosity of intertubular dentin.
  19. 19. >> 0 >> 1 >> 2 >> 3 >> 4 >> Conditioning of dentin: Various acids used Phosphoric Citric Maleic Nitric
  20. 20. >> 0 >> 1 >> 2 >> 3 >> 4 >> Concept of a Dentin Bonding Agent: D E N T I N COMPOSITE Dentin Bonding Agent HYDROPHILIC HYDROPHOBIC
  21. 21. >> 0 >> 1 >> 2 >> 3 >> 4 >> Classification of Bonding Agents based on their shear bond strength: (Eick et al, 1991) Three categories of dentinal adhesives are proposed: • Category I includes adhesives with shear bond strength values between 5 and 7 Mpa; • Category II includes dentinal adhesives with shear bond strengths between 8 and 14 Mpa; and • Category III includes adhesives with shear bond strength values above 20 Mpa .
  22. 22. >> 0 >> 1 >> 2 >> 3 >> 4 >> Clinical significance of this classification: • Polymerization shrinkage – 2.9 to 7.1% by volume – contraction gap – 17-20 MPa bond strength to overcome (Davidson et al)
  23. 23. >> 0 >> 1 >> 2 >> 3 >> 4 >> According to generations: Evolution of bonding agents from No etch to total etch and self etch.
  24. 24. >> 0 >> 1 >> 2 >> 3 >> 4 >> Evolution of Dentin Bonding Agents: • First Generation. • Second Generation. • Third Generation. • Fourth Generation. • Fifth Generation. • Sixth Generation. • Seventh Generation.
  25. 25. >> 0 >> 1 >> 2 >> 3 >> 4 >> Factors influencing the evolution of bonding systems: • Etching enamel • Etching/conditioning Dentin • Smear Layer Treatment • Handling properties
  26. 26. >> 0 >> 1 >> 2 >> 3 >> 4 >> First Generation • These contained N-phenylglycine and glycidyl methacrylate or NPG-GMA. • NPG-GMA is a bifunctional molecule or coupling agent. • This means that one end of this molecule bonds to dentin while the other bonds (polymerizes) to composite resin. • The bond strengths of these early systems were only 1 to 3 MPa.
  27. 27. >> 0 >> 1 >> 2 >> 3 >> 4 >> Second Generation • In the late1970s, the second-generation systems were introduced. • The majority of these incorporated halophosphorous esters of unfilled resins such as bisphenol- A glycidyl methacrylate, or bis-GMA, or hydroxyethyl methacrylate, or HEMA. • The mechanism by which these bonded to dentin were postulated to be through an ionic bond to calcium by chlorophosphate groups. • These were weak bonds with a range of 2-7 MPa.
  28. 28. >> 0 >> 1 >> 2 >> 3 >> 4 >> Drawbacks: • Since dentin was not etched in these early bonding systems bonding was with the smear layer. • Water immersion.
  29. 29. >> 0 >> 1 >> 2 >> 3 >> 4 >> Third Generation • Three step systems. • Dentin etching was introduced by Fusuyama. • Followed by a primer application. • Application of an unfilled resin.
  30. 30. >> 0 >> 1 >> 2 >> 3 >> 4 >> Dentin Primer: • The primer contains hydrophilic resin monomers which include hydroxyethyl trimellitate anhydride, or 4-META, and biphenyl dimethacrylate, or BPDM. • The primers contain a hydrophilic group that infiltrates the smear layer, modifying it and promoting adhesion to dentin, and the hydrophobic group of the primer creates adhesion to the resin. • Dentin primers may be 6 % phosphate penta- acrylate, (PENTA) ; 30 % HEMA; and 64 % ethanol.
  31. 31. >> 0 >> 1 >> 2 >> 3 >> 4 >> Examples: Denthesive
  32. 32. >> 0 >> 1 >> 2 >> 3 >> 4 >> Fourth Generation • The fourth generation bonding system contains two or more bottles. • One consists of the primer and the other the adhesive.
  33. 33. >> 0 >> 1 >> 2 >> 3 >> 4 >> Etchant Primer Adhesive+ + Etchant Primer AdhesivePrimer and adhesive 3 step total etch IV Generation The conditioning step → priming step → Adhesive application.
  34. 34. >> 0 >> 1 >> 2 >> 3 >> 4 >> Here the complete removal of the smear layer is achieved .
  35. 35. >> 0 >> 1 >> 2 >> 3 >> 4 >> Fourth Generation • Fusayama and colleagues tried to simplify bonding to enamel and dentin by total etching the preparation with 40 percent phosphoric acid. • The mineralized tissues of the peritubular and intertubular dentin are dissolved by the acidic action; the initial surface penetration exposes the collagen fibers. • In this area, for a depth of 2 to 4 micrometers, hybridization takes place, and resin tags can seal the tubule orifices firmly.
  36. 36. >> 0 >> 1 >> 2 >> 3 >> 4 >> Hybridisation Zone • Results from the polymerized methacrylate and dentin. • The hybrid layer is defined as “the structure formed in dental hard tissues (enamel, dentin, cementum) by demineralization of the surface and subsurface, followed by infiltration of monomers and subsequent polymerization.” Nakabayashi et al (1982)
  37. 37. >> 0 >> 1 >> 2 >> 3 >> 4 >> Hybrid zone Hybrid zone
  38. 38. >> 0 >> 1 >> 2 >> 3 >> 4 >> • The formation of resin tags and adhesive lateral branches complete the bonding mechanism between the adhesive material and etched dentin substrate.
  39. 39. >> 0 >> 1 >> 2 >> 3 >> 4 >> Examples: All Bond 2 Pro-Bond Liner Bond 2 Scotch Bond
  40. 40. >> 0 >> 1 >> 2 >> 3 >> 4 >> Fifth Generation • Unique feature is the combination of the priming and bond resin application steps, resulting in a one component formula. • Also rely heavily on wet bonding. • Most commonly used and probably the most successful system.
  41. 41. >> 0 >> 1 >> 2 >> 3 >> 4 >> Fifth Generation • These bonding systems create a mechanical interlocking with etched dentin by means of resin tags, adhesive lateral branches and hybrid layer formation..
  42. 42. >> 0 >> 1 >> 2 >> 3 >> 4 >> Etchant Primer Adhesive+ + Etchant + Primer Adhesive Primer and adhesive 3 step total etch IV Generation 2 step V Generation
  43. 43. >> 0 >> 1 >> 2 >> 3 >> 4 >> Examples: Prime & Bond- NT Adper Single Bond Optibond Solo Gluma Comfort Bond
  44. 44. >> 0 >> 1 >> 2 >> 3 >> 4 >> Inter-comparison of V Generation: Adhesive Mean Shear Bond Strength ( MPa ) Single Bond 30.0±5.5 Opti Bond Solo 23.4±3.4 One-Step 22.5±3.8 Prime & Bond 2.1 21.1±5.0
  45. 45. >> 0 >> 1 >> 2 >> 3 >> 4 >> Sixth Generation • They are self etching adhesives ( Etch & prime simultaneously). • They involve a somewhat different mechanism in that, as soon as the decalcification process is initiated, the infusion of the evacuated spaces by dentin bonding agent is begun. • As a result, the potential for residual vacancies amongst the collagenous fibers is dramatically reduced or eliminated altogether. • The bonding agent is either applied after the self etching primer or mixed together before single application.
  46. 46. >> 0 >> 1 >> 2 >> 3 >> 4 >> Etchant Primer Adhesive Etchant Primer Adhesive + + + + Self etching primer All in one adhesive Sixth Generation Type I Sixth Generation Type II
  47. 47. >> 0 >> 1 >> 2 >> 3 >> 4 >> Examples: Xeno IIIPrompt L Pop Clearfil SE Bond
  48. 48. >> 0 >> 1 >> 2 >> 3 >> 4 >> Seventh Generation Etchant Primer Adhesive+ + Etchant Primer Adhesive = All in one adhesive
  49. 49. >> 0 >> 1 >> 2 >> 3 >> 4 >> Seventh Generation I- Bond Xeno IVG Bond
  50. 50. >> 0 >> 1 >> 2 >> 3 >> 4 >> Classification of Bonding Agents based on their effect on smear layer: 1. Modify the smear layer & incorporate it into the bond. • One step – Prime & Bond 2.1 • Two step – Pro Bond
  51. 51. >> 0 >> 1 >> 2 >> 3 >> 4 >> 2. Completely removes the smear layer: • Two step – Clearfil Liner Bond 2. • Three step – Clearfil Liner Bond.
  52. 52. >> 0 >> 1 >> 2 >> 3 >> 4 >> 3. Dissolves the smear layer than removing it. • Prime & Bond 2.0.
  53. 53. >> 0 >> 1 >> 2 >> 3 >> 4 >> Differences between dentin in primary and permanent teeth: • Difference in the degree of mineralisation. • Concentrations of both calcium and phosphorus in both peritubular and intertubular dentin are lower in primary teeth. • The tubular diameter and density in dentin of primary teeth is lesser than that in permanent teeth.
  54. 54. >> 0 >> 1 >> 2 >> 3 >> 4 >> Bonding to dentin in primary teeth: • Dentin of primary teeth is more sensitive to the acid etch/ conditioning procedure. • This leads to an increased thickness of the hybrid layer and the subsequent lack of complete penetration of the adhesive resin into the demineralised dentin. • Ideally the concentration and duration of etch/ conditioning has to be re-calculated for primary teeth.
  55. 55. >> 0 >> 1 >> 2 >> 3 >> 4 >> Bonding to carious dentin in primary teeth: • Carious dentin is a combination of porous and non- porous zones. • The resultant deposition of Whitlockite may warrant additional etching/ conditioning times compared to sound dentin.
  56. 56. >> 0 >> 1 >> 2 >> 3 >> 4 >> Clinical requirements of a bonding system for use in pediatric dentistry: • Simple to use. • Minimally irritating to the tissue. • Less technique sensitive. • Clinically satisfactory bond.
  57. 57. >> 0 >> 1 >> 2 >> 3 >> 4 >> The future of dentin bonding • Chemically bonding the resin molecule to the collagenous structure of dentin rather than by means of micromechanical retention (as is done now). • Incidentally, another approach to dentinal adhesion could center on the chemical bonding of the resin to the hydroxyapatite .
  58. 58. >> 0 >> 1 >> 2 >> 3 >> 4 >> Celebrate the bond of Love! Conclusion
  59. 59. >> 0 >> 1 >> 2 >> 3 >> 4 >> Enjoy!
  60. 60. >> 0 >> 1 >> 2 >> 3 >> 4 >> Thank You!............
  61. 61. >> 0 >> 1 >> 2 >> 3 >> 4 >>
  62. 62. >> 0 >> 1 >> 2 >> 3 >> 4 >> Differences: • Prime & Bond 2.0 – Total etch • Prime & Bond 2.1 – No etch • Prime & Bond NT – Nano-Technology
  63. 63. >> 0 >> 1 >> 2 >> 3 >> 4 >> Wet Bonding Technique: • Drying the dentin will produce a relatively impermeable amorphous layer: – Denatured collagen – Collapse of collagen layer • Must remain moist to resist this impermeable layer. • Pooled moisture should be removed by blotting and not with a blast of air. • Dry dentin should be remoistened with a wet cotton pledget.
  64. 64. >> 0 >> 1 >> 2 >> 3 >> 4 >> Etched dried dentin
  65. 65. >> 0 >> 1 >> 2 >> 3 >> 4 >> Etched moist dentin
  66. 66. >> 0 >> 1 >> 2 >> 3 >> 4 >> Selective etch v/s Total etch: • The total-etch technique permits the etching of enamel and dentin simultaneously using phosphoric acid for 15 to 20 seconds. • The surface must be left moist (“wet bonding”), however, in order to avoid collagen collapse . • The application of a hydrophilic primer solution infiltrates the exposed collagen network forming the hybrid layer .
  67. 67. >> 0 >> 1 >> 2 >> 3 >> 4 >> Smear layer not removed in second generation adhesives Bonding Agent Smear Layer

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