title: Influence of in situ postbleaching times on shear bond strength of resin-based composite restorations.
abstract: BACKGROUND
  The authors conducted an in situ study of the influence of various time intervals after tooth bleaching with 35 percent hydrogen peroxide on the bond strength of resin-based composite restorations.
  
  
  METHODS
  After selecting 20 participants, the authors randomly fixed enamel and dentin blocks onto the buccal surfaces of posterior maxillary teeth one week before performing tooth bleaching with 35 percent hydrogen peroxide. After the bleaching treatment, they removed one block of dentin or enamel and prepared it for the bond strength tests according to these time intervals: no bleaching treatment (controls), immediately after bleaching, seven days after bleaching, 14 days after bleaching and 21 days after bleaching.
  
  
  RESULTS
  The analysis of variance and Tukey test showed significant differences between times (P<.05), and shear bond strength values of resin-based composite to enamel and dentin were lower immediately after the bleaching treatment.
  
  
  CONCLUSIONS
  The authors found that 35 percent hydrogen peroxide reduces the bond strength to enamel and dentin and that it is necessary to wait seven days before performing adhesive restorative procedures.
  
  
  CONCLUSIONS
  The results of this study suggest that clinicians should allow seven days to elapse after completion of in-office bleaching with 35 percent hydrogen peroxide before placing adhesive restorations.
authors.affiliation: Department of Restorative Dentistry, São Leopoldo Mandic Research Center, Campinas, São Paulo, Brazil.
authors.forename: Marcos Eugenio
authors.initials: ME
authors.lastname: Bittencourt
authors.forename: Micheline Sandini
authors.initials: MS
authors.lastname: Trentin
authors.forename: Maria Salete Sandini
authors.initials: MS
authors.lastname: Linden
authors.forename: Ynara Bosco
authors.initials: YB
authors.lastname: de Oliveira Lima Arsati
authors.forename: Fabiana Mantovani Gomes
authors.initials: FM
authors.lastname: França
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; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D055117:Curing Lights, Dental; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000648:ultrastructure; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000627:therapeutic use; D008422:Materials Testing; D016877:Oxidants / Q000737:chemistry / Q000627:therapeutic use; D033081:Shear Strength; D013314:Stress, Mechanical; D013997:Time Factors; D014073:Tooth Bleaching / Q000379:methods*
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D016877:Oxidants; C511238:Single Bond Plus; D017438:Bisphenol A-Glycidyl Methacrylate; D006861:Hydrogen Peroxide