title: Effects of tooth bleaching on shear bond strength of brackets rebonded with a self-etching adhesive system.
abstract: The purpose of this study was to ascertain the effects of tooth bleaching on the shear bond strength of orthodontic brackets rebonded with a self-etching adhesive system. A total of 39 premolars were collected and divided into three equal groups: in group 1 bracket bonding was performed without bleaching treatment; specimens in group 2 were bonded immediately after bleaching; and group 3 teeth were bleached, then immersed in artificial saliva and left for 7 days before bonding. The shear bond strength was measured, with the bonding/debonding procedures repeated once after the first debonding, and the bracket/adhesive failure modes were evaluated by the adhesive remnant index after each debonding. Excepting the mean shear bond strength for group 2 after the first debonding, the overall mean values reached the minimum clinical requirement of 6 MPa. The mean values at the first and second debondings were significantly higher in groups 1 and 3 than in group 2. Between groups 1 and 3, significant differences were noted at the first debonding, but not at the second debonding. Group 2 showed significant differences in mean shear bond strength between the first and second debondings. Bond failure at the enamel-adhesive interface occurred more frequently in group 2 than in groups 1 or 3 after the first debonding. The bracket-rebonding procedure can recover the reduced shear bond strength caused by immediate bonding after bleaching to a clinically acceptable level, but not to the prebleaching level.
authors.affiliation: Orthodontic Dentistry, The Nippon Dental University Niigata Hospital, 1-8 Hamaura-cho, Chuo-ku, Niigata, 951-8580, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Abe
authors.affiliation: Orthodontic Dentistry, The Nippon Dental University Niigata Hospital, 1-8 Hamaura-cho, Chuo-ku, Niigata, 951-8580, Japan. endoto@ngt.ndu.ac.jp.
authors.forename: Toshiya
authors.initials: T
authors.lastname: Endo
authors.affiliation: Department of Pediatric Dentistry, The Nippon Dental University School of Life Dentistry at Niigata, Niigata, Japan.
authors.forename: Shohachi
authors.initials: S
authors.lastname: Shimooka
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D000704:Analysis of Variance; D001641:Bicuspid; D016009:Chi-Square Distribution; D003722:Dental Alloys; D001840:Dental Bonding / Q000379:methods; D017005:Dental Debonding; D003799:Dental Stress Analysis; D006801:Humans; D006861:Hydrogen Peroxide; D008422:Materials Testing; D016910:Orthodontic Brackets; D019279:Resin Cements; D033081:Shear Strength; D013193:Stainless Steel; D018709:Statistics, Nonparametric; D013997:Time Factors; D014073:Tooth Bleaching; D058205:Tooth Bleaching Agents
chemical_list: D003722:Dental Alloys; D019279:Resin Cements; D058205:Tooth Bleaching Agents; C429625:Transbond Plus Self-Etching Primer; C477790:Transbond XT; D013193:Stainless Steel; D006861:Hydrogen Peroxide