title: Effect of Delayed Bonding and Antioxidant Application on the Bond Strength to Enamel after Internal Bleaching.
abstract: OBJECTIVE
  This study evaluated the effect of delayed bonding and antioxidant application (AA, 10% sodium ascorbate) after internal bleaching (35% carbamide peroxide) on the shear bond strength of an adhesive cement to enamel.
  
  
  METHODS
  Eighty-four human maxillary central incisors were endodontically treated. The control group remained unbleached with no AA. Experimental groups were all internally bleached. The buccal enamel was finished and polished with metallographic paper to a refinement of #600, in order to obtain a 5-mm(2) flat bonding area. An adhesive cement (Clearfil Esthetic) was placed into a plastic tube with internal diameter of 3 mm and a 3-mm height and cured on the enamel. Bonding occurred either immediately after bleaching (group Im), a 7-day delay (group 7), or a 14-day delay (group 14), and half the specimens were treated with antioxidant application (groups Im-AA, 7-AA, and 14-AA). Shear bond strength testing was performed on a universal testing machine, and data were analyzed with ANOVA and Fisher test (5%).
  
  
  RESULTS
  Delaying of bonding is a useful factor for enhancing shear bond strength (p < 0.05), whereas AA only enhanced shear bond strength after 7 days delayed bleaching (p < 0.05). The highest bond strength was noted in groups 7-AA (20.51 ± 4.5 MPa), 14 (19.82 ± 4.6), 14-AA (20.27 ± 4.4), and control (20.51 ± 5.1), which were not significantly different from each other.
  
  
  CONCLUSIONS
  After internal bleaching, adhesive cementation to enamel is recommended only when delayed 14 days, or delayed 7 days with sodium ascorbate application.
authors.affiliation: Department of Prosthodontics, Erciyes University, Faculty of Dentistry, Kayseri, Turkey.
authors.forename: Halil İbrahim
authors.initials: Hİ
authors.lastname: Kılınç
authors.affiliation: Department of Restorative Dentistry and Endodontics, Erciyes University, Faculty of Dentistry, Kayseri, Turkey.
authors.forename: Tuğrul
authors.initials: T
authors.lastname: Aslan
authors.affiliation: Department of Prosthodontics, Erciyes University, Faculty of Dentistry, Kayseri, Turkey.
authors.forename: Kerem
authors.initials: K
authors.lastname: Kılıç
authors.affiliation: Department of Endodontics, Trakya University, Faculty of Dentistry, Edirne, Turkey.
authors.forename: Özgür
authors.initials: Ö
authors.lastname: Er
authors.affiliation: Department of Orthodontics, Yeni Yüzyıl University, Faculty of Dentistry, İstanbul, Turkey.
authors.forename: Gökmen
authors.initials: G
authors.lastname: Kurt
mesh_terms: D003188:Composite Resins; D001840:Dental Bonding; D003738:Dental Cements; D003743:Dental Enamel; D003799:Dental Stress Analysis; D004955:Esthetics, Dental; D006801:Humans; D008422:Materials Testing; D010545:Peroxides; D033081:Shear Strength; D014073:Tooth Bleaching; D014508:Urea
chemical_list: D003188:Composite Resins; D003738:Dental Cements; D010545:Peroxides; D014508:Urea
keywords: Internal bleaching; antioxidant; bonding; enamel