title: Reversal of compromised bonding in bleached enamel.
abstract: Oxygen inhibits polymerization of resin-based materials. We hypothesized that compromised bonding to bleached enamel can be reversed with sodium ascorbate, an anti-oxidant. Sandblasted human enamel specimens were treated with distilled water (control) and 10% carbamide peroxide gel with or without further treatment with 10% sodium ascorbate. They were bonded with Single Bond (3M-ESPE) or Prime&Bond NT (Dentsply DeTrey) and restored with a composite. Specimens were prepared for microtensile bond testing and transmission electron microscopy after immersion in ammoniacal silver nitrate for nanoleakage evaluation. Bond strengths of both adhesives were reduced after bleaching but were reversed following sodium ascorbate treatment (P < 0.001). Resin-enamel interfaces in bleached enamel exhibited more extensive nanoleakage in the form of isolated silver grains and bubble-like silver deposits. Reduction of resin-enamel bond strength in bleached etched enamel is likely to be caused by a delayed release of oxygen that affects the polymerization of resin components.
authors.affiliation: Conservative Dentistry, Faculty of Dentistry, University of Hong Kong, Prince Philip Dental Hospital, 34 Hospital Road, SAR, China.
authors.forename: S C N
authors.initials: SC
authors.lastname: Lai
authors.forename: F R
authors.initials: FR
authors.lastname: Tay
authors.forename: G S P
authors.initials: GS
authors.lastname: Cheung
authors.forename: Y F
authors.initials: YF
authors.lastname: Mak
authors.forename: R M
authors.initials: RM
authors.lastname: Carvalho
authors.forename: S H Y
authors.initials: SH
authors.lastname: Wei
authors.forename: M
authors.initials: M
authors.lastname: Toledano
authors.forename: R
authors.initials: R
authors.lastname: Osorio
authors.forename: D H
authors.initials: DH
authors.lastname: Pashley
mesh_terms: D000134:Acid Etching, Dental; D000704:Analysis of Variance; D000975:Antioxidants / Q000737:chemistry*; D001205:Ascorbic Acid / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D000077463:Carbamide Peroxide; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003743:Dental Enamel / Q000187:drug effects / Q000648:ultrastructure*; D003763:Dental Leakage / Q000145:classification; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D004338:Drug Combinations; D006801:Humans; D008854:Microscopy, Electron; D016877:Oxidants / Q000494:pharmacology; D010084:Oxidation-Reduction; D010545:Peroxides / Q000494:pharmacology; D011108:Polymers / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D012834:Silver; D016622:Silver Staining; D013223:Statistics as Topic; D013499:Surface Properties; D013718:Tensile Strength; D014073:Tooth Bleaching; D014508:Urea / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D004338:Drug Combinations; D016877:Oxidants; D010545:Peroxides; D011108:Polymers; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT; C000212:ammoniacal silver; C115612:single bond; D000077463:Carbamide Peroxide; D012834:Silver; D017438:Bisphenol A-Glycidyl Methacrylate; D014508:Urea; D001205:Ascorbic Acid