title: Reversal of compromised bonding to oxidized etched dentin.
abstract: The mechanism responsible for hydrogen-peroxide- or sodium-hypochlorite-induced reductions in dentin bond strength is unknown. This in vitro study tested the hypothesis that these oxidizing agents were responsible by attempting to reverse the effect with sodium ascorbate, a reducing agent. Human dentin was treated with these oxidants before or after being acid-etched and with or without post-treatment with sodium ascorbate. They were bonded with either Single Bond or Excite. Hydrogen peroxide reduced the bond strengths of both adhesives, while sodium hypochlorite produced reduction in adhesion of only Single Bond (p < 0.05). Following treatment with sodium ascorbate, reductions in bond strength were reversed. Transmission and scanning electron microscopy showed partial removal of the demineralized collagen matrix only by sodium hypochlorite. The observed compromised bond strengths cannot be attributed to incomplete deproteinization and may be related to changes in the redox potential of the bonding substrates.
authors.affiliation: Faculty of Dentistry, University of Hong Kong, Prince Philip Dental Hospital, SAR, China.
authors.forename: S C
authors.initials: SC
authors.lastname: Lai
authors.forename: Y F
authors.initials: YF
authors.lastname: Mak
authors.forename: G S
authors.initials: GS
authors.lastname: Cheung
authors.forename: R
authors.initials: R
authors.lastname: Osorio
authors.forename: M
authors.initials: M
authors.lastname: Toledano
authors.forename: R M
authors.initials: RM
authors.lastname: Carvalho
authors.forename: F R
authors.initials: FR
authors.lastname: Tay
authors.forename: D H
authors.initials: DH
authors.lastname: Pashley
mesh_terms: D000134:Acid Etching, Dental; D000268:Adhesiveness; D000704:Analysis of Variance; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000737:chemistry / Q000494:pharmacology*; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003094:Collagen / Q000187:drug effects / Q000648:ultrastructure; D001840:Dental Bonding; D003804:Dentin / Q000187:drug effects* / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000494:pharmacology*; D008689:Methacrylates / Q000737:chemistry; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D016877:Oxidants / Q000737:chemistry / Q000494:pharmacology*; D010084:Oxidation-Reduction; D012973:Sodium Hypochlorite / Q000737:chemistry / Q000494:pharmacology*; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D000975:Antioxidants; D017220:Dentin-Bonding Agents; C420130:Excite cement; D008689:Methacrylates; D016877:Oxidants; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate; D003094:Collagen; D006861:Hydrogen Peroxide; D012973:Sodium Hypochlorite; D001205:Ascorbic Acid