title: Influence of in situ post-bleaching times on resin composite shear bond strength to enamel and dentin.
abstract: OBJECTIVE
  To evaluate in situ the influence of time after treatment with a 16% carbamide peroxide home-use bleaching agent on the shear bond strength of resin-based composite to human enamel and dentin.
  
  
  METHODS
  80 enamel slabs (E) and 80 dentin slabs (D) were obtained, embedded, flattened, sterilized and randomly fixed on the buccal surface of teeth in 20 volunteers. These specimens were submitted to treatment with a 16% carbamide peroxide bleaching agent (Pola Night) for 2 hours a day, for 3 weeks. The control group (C) consisted of slabs that were fixed on buccal tooth faces that did not receive any bleaching treatment. For the experimental groups, three slabs of E and three slabs of D were fixed to teeth of the same volunteers, and after bleaching treatment, the slabs were removed at different times: EI--immediate removal; E7--removal 7 days after treatment ended; E14--removal 14 days after treatment ended. After removal, the slabs were again embedded and microhybrid composite resin cylinders (Filtek Z250) were constructed and bonded using a one-bottle adhesive system (Single Bond) for shear bond strength tests. These tests were performed in a universal testing machine, with a speed of 0.5 mm/minute, with the data returned in MPa. The results were submitted to the ANOVA test.
  
  
  RESULTS
  There were no significant differences with regards to the timespan for the E and D groups (P > 0.05). For the fracture mode analysis, there was a predominance of adhesive failures for Groups C, EI and E14 in enamel, with the same adhesive failures occurred for all groups in dentin. It was concluded that restorative procedures may be performed immediately after the end of the bleaching treatment.
authors.affiliation: Faculty of Dentistry and Dental Research Center São Leopoldo Mandic, Department of Restorative Dentistry - Operative, Rua José Rocha Junqueira, 13 Bairro Swift, Campinas, SP, CEP: 13045-755, Brazil.
authors.forename: Cinthia Maria
authors.initials: CM
authors.lastname: Barbosa
authors.forename: Robson Tetsuo
authors.initials: RT
authors.lastname: Sasaki
authors.forename: Flávia Martão
authors.initials: FM
authors.lastname: Flório
authors.forename: Roberta Tarkany
authors.initials: RT
authors.lastname: Basting
mesh_terms: D000134:Acid Etching, Dental; D000268:Adhesiveness; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D000077463:Carbamide Peroxide; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003743:Dental Enamel / Q000187:drug effects / Q000648:ultrastructure*; D003764:Dental Materials / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000187:drug effects / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D004338:Drug Combinations; D005500:Follow-Up Studies; D006801:Humans; D016877:Oxidants / Q000737:chemistry / Q000627:therapeutic use; D010545:Peroxides / Q000737:chemistry / Q000627:therapeutic use; D033081:Shear Strength; D013314:Stress, Mechanical; D013997:Time Factors; D014073:Tooth Bleaching / Q000379:methods*; D014508:Urea / Q000031:analogs & derivatives / Q000737:chemistry / Q000627:therapeutic use
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; D004338:Drug Combinations; C444701:Filtek Z250; D016877:Oxidants; D010545:Peroxides; C115612:single bond; D000077463:Carbamide Peroxide; D017438:Bisphenol A-Glycidyl Methacrylate; D014508:Urea