title: Effect of pre- and postoperative bleaching on marginal leakage of amalgam and composite restorations.
abstract: OBJECTIVE
  The aim of this study was to investigate the effect of pre- and postoperative bleaching with 10% carbamide peroxide on marginal leakage of amalgam and resin composite restorations.
  
  
  METHODS
  Three groups were made using 30 extracted, caries-free third molars (n = 10). In the preoperative group, bleaching was performed with 10% carbamide peroxide, followed by the placement of resin composite and amalgam restorations on Class V cavity preparations. In the postoperative group, bleaching was performed after the resin composite and amalgam restorations were fabricated. The third group served as a control in which no bleaching was performed. Dye penetration was used for evaluation of marginal leakage.
  
  
  RESULTS
  Chi-square test showed that marginal leakage of resin composite restorations increased in both pre- and postoperatively bleached groups, but marginal leakage of amalgam restorations showed no alterations.
  
  
  CONCLUSIONS
  Bleaching with carbamide peroxide may alter the marginal leakage of resin composite restorations, but amalgam restorations are not affected adversely in vitro.
authors.affiliation: Department of Conservative Dentistry, Faculty of Dentistry, Istanbul University, Istanbul, Turkey. ulukapi@istanbul.edu.tr
authors.forename: Haşmet
authors.initials: H
authors.lastname: Ulukapi
authors.forename: Yasemin
authors.initials: Y
authors.lastname: Benderli
authors.forename: Işin
authors.initials: I
authors.lastname: Ulukapi
mesh_terms: D000077463:Carbamide Peroxide; D016009:Chi-Square Distribution; D004396:Coloring Agents; D003188:Composite Resins / Q000737:chemistry; D003723:Dental Amalgam / Q000737:chemistry; D003737:Dental Cavity Preparation / Q000145:classification; D003763:Dental Leakage / Q000145:classification*; D003793:Dental Restoration, Permanent / Q000145:classification; D004338:Drug Combinations; D006801:Humans; D016877:Oxidants / Q000627:therapeutic use; D010545:Peroxides / Q000627:therapeutic use; D013499:Surface Properties; D013816:Thermodynamics; D013997:Time Factors; D014073:Tooth Bleaching; D014508:Urea / Q000031:analogs & derivatives / Q000627:therapeutic use
chemical_list: D004396:Coloring Agents; D003188:Composite Resins; D004338:Drug Combinations; D016877:Oxidants; D010545:Peroxides; D000077463:Carbamide Peroxide; D003723:Dental Amalgam; D014508:Urea