title: Can previously bleached teeth be bonded safely using self-etching primer systems?
abstract: OBJECTIVE
  To test the null hypothesis that there is no statistical significance in (1) bond strength and (2) failure site location with bleached and unbleached enamel prepared with Transbond Plus Self-etching Primer between different time intervals.
  
  
  METHODS
  Sixty freshly extracted human premolar teeth were randomly divided into three groups of 20 teeth each. Bleaching treatment was performed at two different time intervals (bleaching immediately before bonding and bleaching 30 days before bonding). All brackets were bonded with a self-etching primer system. The shear bond strength of these brackets was measured and recorded in MPa. Adhesive remnant index (ARI) scores were determined after the brackets failed. Data were analyzed with analysis of variance, Tukey, and chi2 tests.
  
  
  RESULTS
  The bond strengths of group 1 (no bleaching, mean: 17.60 +/- 7.93 MPa) and group 3 (bleaching 30 days before bonding, mean: 13.95 +/- 5.23 MPa) were significantly higher (P < .05) than that of group 2 (bleaching immediately before bonding, mean: 11.45 +/- 5.25 MPa). No statistically significant differences were found between groups 1 and 3 (P > .05). ARI scores were significantly different among the three groups. In groups 1 and 2, there was a higher frequency of ARI scores of 2 to 4, indicating cohesive failures within the resin. In group 3, the failures were shown to be adhesive (resin/enamel interface) and cohesive characteristics.
  
  
  CONCLUSIONS
  The use of a carbamide peroxide bleaching agent immediately before bonding significantly reduces the shear bond strength values of self-etching primer systems.
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Erciyes University, Kayseri, Turkey. tancanuysal@yahoo.com
authors.forename: Tancan
authors.initials: T
authors.lastname: Uysal
authors.forename: Ayca
authors.initials: A
authors.lastname: Sisman
mesh_terms: D000704:Analysis of Variance; D001641:Bicuspid; D000077463:Carbamide Peroxide; D016009:Chi-Square Distribution; D001840:Dental Bonding; D003743:Dental Enamel / Q000187:drug effects; D045662:Dental Etching / Q000379:methods; D003799:Dental Stress Analysis; D004338:Drug Combinations; D006801:Humans; D008422:Materials Testing; D016910:Orthodontic Brackets; D016877:Oxidants / Q000009:adverse effects; D010545:Peroxides / Q000009:adverse effects; D019279:Resin Cements; D033081:Shear Strength; D018709:Statistics, Nonparametric; D013499:Surface Properties / Q000187:drug effects; D013997:Time Factors; D014073:Tooth Bleaching; D014508:Urea / Q000009:adverse effects / Q000031:analogs & derivatives
chemical_list: D004338:Drug Combinations; D016877:Oxidants; D010545:Peroxides; D019279:Resin Cements; C429625:Transbond Plus Self-Etching Primer; D000077463:Carbamide Peroxide; D014508:Urea