title: Effects of different intracoronal bleaching methods on shear bond strengths of orthodontic brackets.
abstract: OBJECTIVE
  To evaluate the effects of different intracoronal bleaching methods on the shear bond strengths (SBS) of orthodontic brackets.
  
  
  METHODS
  Sixty freshly extracted mandibular incisors were randomly divided into four groups (n = 15 per group). After filling the root canals, root fillings were removed 2 mm apical to the cementoenamel junction, and a 2-mm-thick layer of zinc-phosphate cement base was applied. Group 1 served as the control. Intracoronal bleaching was performed with hydrogen peroxide (Opalacence Endo, Ultradent products Inc, South Jordan, Utah) in group 2, sodium perborate (Sultan Healthcare, Englewood, NJ) in group 3, and 37% carbamide peroxide (Whiteness Super Endo, Dentscare, ltda, Joinville, Brazil) in group 4. Orthodontic brackets were bonded with a light cure composite resin and cured with an LED light. After bonding, the SBS of the brackets was tested with a Universal testing machine.
  
  
  RESULTS
  Analysis of variance indicated a significant difference between groups (P < .001). The highest values for SBS were measured in group 1 (10.15 ± 1.15 MPa). The SBS was significantly lower in groups 2, 3, and 4 than in group 1 (P < .001). The lowest values for SBS were measured in group 3 (6.17 ± 0.85 MPa). SBS was significantly higher in group 4 than in group 3 (P < .05).
  
  
  CONCLUSIONS
  Intracoronal bleaching significantly affected the SBS of orthodontic brackets on human enamel. Bleaching with sodium perborate affects SBS more adversely than does bleaching with other agents.
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, University of Akdeniz, Antalya, Turkey. aygungor@gmail.com
authors.forename: Ahmet Yalcin
authors.initials: AY
authors.lastname: Gungor
authors.forename: Erhan
authors.initials: E
authors.lastname: Ozcan
authors.forename: Huseyin
authors.initials: H
authors.lastname: Alkis
authors.forename: Hakan
authors.initials: H
authors.lastname: Turkkahraman
mesh_terms: D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000494:pharmacology*; D001840:Dental Bonding / Q000379:methods; D003743:Dental Enamel / Q000187:drug effects*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D016910:Orthodontic Brackets; D019279:Resin Cements / Q000737:chemistry; D033081:Shear Strength; D014073:Tooth Bleaching / Q000009:adverse effects / Q000379:methods*
chemical_list: D019279:Resin Cements; D017438:Bisphenol A-Glycidyl Methacrylate; D006861:Hydrogen Peroxide