5)Adhesive Systems.pdf

Adhesive Systems Asst. Prof. Dr. Gülşah YENİER Istanbul Okan University Faculty of Dentistry Adhesive system Etching, surface demineralisation by removing hydroxyapetite and increasing surface energy Priming, increasing the wettability of the adhesive on the substrate Bonding, infiltration the subst...

Adhesive Systems Asst. Prof. Dr. Gülşah YENİER Istanbul Okan University Faculty of Dentistry Adhesive system Etching, surface demineralisation by removing hydroxyapetite and increasing surface energy Priming, increasing the wettability of the adhesive on the substrate Bonding, infiltration the substrate and create the actual bond Enamel etching Ortophosphoric acid concentration 30%- 40% Time 15-60 sec. Significant increase in the area for bonding and free surface energy Greater wetting and bonding capabilities. Dentin etching Application of ortophosphoric acid 30-40% Max. 15 sec. Avoid overdrying; Air syringe is far from 5-6 cm Dentin mouisture is important Acetone based: very moist dentin Water based: dentin less humid Alcohol based: intermediate Dentin Etching Removal or dissolution and infiltration of smear layer Removing inorganic component Exposing collagen fibers at the intertubuler and peritubuler level More interfibriller space; the greater bond strength Primer Primer hydrophilic monomers usually carried in a solvent like acetone, ethanol, water Increasing smear layer permeability Improving dentin wettability ; decreasing contact angle Changing collagen fiber orientation, more effective monomer penetration Rubbed continuosly on the surface If chalky areas, reapply ~ 5 s. solvent removal by air-dry Shiny surface Bonding Stabilisation of resin-dentin hybrid layer Formation resin tag Not include solvent Bonding Bis-GMA (Bisphenol A diglycidyl methacrylate) and UDMA (Urethan dimethacrylate ) -hyrophobic monomers, TEG-DMA (Triethylene glycol-dimethacrylate ) viscosity HEMA improves wettability, hydrophilic monomers Hybrid layer Exposing collagen Resin penetration into collagen fibers Minimal invaziv cavity preparation Retention and providing the stability of restorations Seal dentin and intertubular structure to protect pulp from microorganism Preventing Post-operatif sensitivity Bonding to composite, amalgam, ceramic materials Classification of Development of Adhesive Systems 1.generation 2.generation 3.generation 4.generation 5.generation 6.generation 7.generation First generation in the late 1970s chelation of the bonding agent to the calcium component of the dentin. Their adhesion to dentin was low; < 2 MPa. debonding at the dentinal interface 2nd generation In the early 1980s The enamel was etched and rinsed Bond to smear layer Not to form hybrid layer Dentin 2-8 Mpa 3rd generation In the late 1980s the first agents that bonded not only to tooth structure but also to dental metals and ceramics. Enamel and dentin etching Dentin 8-15 Mpa, Cavity retention form (-) 4th generation Early 1990s 17- 25 MPa adhesion to dentin Total etch; complete removal of smear layer Bonds to enamel, “moist” dentin, metal, porcelain Multi-bottle, multistep 4th generation Etching Primer Bonding 5th generation Mid 1990s 20 to 25 MPa adhesion to dentin Single component in a single bottle Bonds to enamel, moist dentin, metal, porcelain Etching required Moist surface required (wet or moist bonding) 6th generation Avalaible in 2000 17 to 22 MPa adhesion to dentin No separate etching step Multibottle, multistep Bonds to dentin, metal, porcelain High incidence of enamel interface fractures 6th generation Seperately etching step (-), Etching + primer one bottle Adhesive second bottle 7th generation 2003 20 to 30+ MPa adhesion to dentin Single bottle—no mixing Bonds to enamel, dentin, porcelain, metal Moisture independent No technique sensitivity Classification for the smear layer Smear layer removing Smear layer modified / dissolution Removing smear layer Etch & rinse Total etch Etching enamel and Dentin at the same time Their affecting mechanisms are based on resin tag formation and hybridization Disadvantage of this technique is to be complicated procedure; technical sensivity, timing Modified/ Dissolution of smear layer Self-etch All-in-one O ne bottle Another step of etch and rinse (-) Demineralisation of enamel and dentin at the same time; Primer penetration by acidic monomer (+) Etch &Rinse 3-steps 4.generation 2-steps 5.generation Self-EtcEhtch&Rins 2-steps 6.generation Acid Acid Acid+Primer Primer Primer+Bonding Bonding Bonding 1-step 7.generation Acid+Primer+ Bonding Glass ionomer based adhesive system Polyalkenoic acid removes smear layer and exposes 0.5-1 μm depthness collagen fibers Micromechanical bonding Chemical bonding Ph of the adhesive system Not to demineralize as phosphoric acid in enamel tissue Low bonding strength Enamel Selective Etching Only enamel etching Universal adhesive system Different monomer contents pH: 2,3 - 3,2