title: The effects of high concentration tooth whitening bleaches on microleakage of Class V composite restorations.
abstract: OBJECTIVE
  To explore the effects of high-concentration hydrogen peroxide bleaching agents on the microleakage of composite restorations.
  
  
  METHODS
  In 60 extracted human molars, Class V restorations were prepared with Scotchbond 1/Filtek Z250 composite. Teeth were randomly divided into four groups: (1) no bleaching; (2) bleaching with 14% hydrogen peroxide gel from Crest Whitestrips; (3) bleaching with 20% carbamide peroxide gel from Opalescence PF 20; and (4) bleaching with 38% hydrogen peroxide gel Opalescence Xtra Boost. Bleaching procedures were carried out at 37 degrees C for 21 days/42 hours (2); seven days/42 hours (3); one day/45 minutes (4). Varnish was applied on the apical portion of the teeth only, excluding the restoration, prior to immersion in a 0.1% rhodamin-B-isothiocyanate solution for 24 hours at 37 degrees C. After rinsing, specimens were embedded in methacrylate blocks, and sectioned with a water-cooled microtome with three restoration cuts positioned centrally parallel to the long axis of the tooth. Microleakage was evaluated at the occlusal margins of the Class V restorations using a stereo microscope, separate for dentin and enamel margins.
  
  
  RESULTS
  Over 90% of enamel margins exhibited no microleakage following cycling. Bleaching agents had almost no effect on numerical averages. Eighty-eight percent of the dentin margins were free of microleakage for the non-treated control group. Bleaching treatments collectively had slight numerical reductions to around 80%. The statistical evaluation (Kruskal-Wallis-test) showed no significant difference in microleakage between groups for enamel or dentin.
  
  
  CONCLUSIONS
  Bleaching with the materials tested had no influence on microleakage of Filtek Z250 composite bonded with Scotchbond 1.
authors.affiliation: Health Care Research Center, The Procter and Gamble Company, Mason, OH, USA. Klukowska.m@pg.com
authors.forename: Malgorzata A
authors.initials: MA
authors.lastname: Klukowska
authors.forename: Donald J
authors.initials: DJ
authors.lastname: White
authors.forename: Roger D
authors.initials: RD
authors.lastname: Gibb
authors.forename: Franklin
authors.initials: F
authors.lastname: Garcia-Godoy
authors.forename: Cristina
authors.initials: C
authors.lastname: Garcia-Godoy
authors.forename: Heinz
authors.initials: H
authors.lastname: Duschner
mesh_terms: D000077463:Carbamide Peroxide; D003188:Composite Resins; D003737:Dental Cavity Preparation / Q000145:classification; D003763:Dental Leakage / Q000209:etiology*; D003793:Dental Restoration, Permanent; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D006801:Humans; D006861:Hydrogen Peroxide / Q000008:administration & dosage / Q000009:adverse effects*; D008963:Molar; D016877:Oxidants / Q000008:administration & dosage / Q000009:adverse effects*; D010545:Peroxides / Q000008:administration & dosage / Q000009:adverse effects; D014073:Tooth Bleaching / Q000009:adverse effects*; D014508:Urea / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives
chemical_list: D003188:Composite Resins; D004338:Drug Combinations; C444701:Filtek Z250; D016877:Oxidants; D010545:Peroxides; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide