title: Effect of nonvital bleaching with 10% carbamide peroxide on sealing ability of resin composite restorations.
abstract: OBJECTIVE
  To (i) determine the effect of nonvital bleaching with 10% carbamide peroxide on the sealing ability of resin composite restorations bonded with a self-etching adhesive system; and (ii) compare the effects of antioxidant treatment and delayed restoration after bleaching on marginal seal.
  
  
  METHODS
  Forty-eight noncarious maxillary incisors were divided into four groups (n=12) after conventional root canal treatment was completed. In group 1, access cavities were restored with a self-etching adhesive system and resin composite. In the remaining three groups, 10% carbamide peroxide bleaching gel was placed into the access cavities for periods of 8 h per day for 1 week. They were then restored in the same manner as group 1. Group 2 consisted of specimens restored immediately after bleaching. Group 3 specimens were treated with the antioxidant, 10% sodium ascorbate, whereas group 4 specimens were immersed in artificial saliva for 1 week before restoration. Ten specimens in each group were then subjected to dye leakage; the remaining 2 specimens were examined in a SEM (Jeol/JSM 5200, Tokyo, Japan). The dye penetration was assessed with the standard scoring system. Statistical analysis was carried out using the Kruskal-Wallis and the Mann-Whitney tests.
  
  
  RESULTS
  Groups 1, 3 and 4 exhibited similar leakage patterns and significantly less leakage than group 2 (P<0.0083). SEM examination of groups 1, 3 and 4 specimens demonstrated close adaptation of resin composite to cavity walls, whereas group 2 specimens did not.
  
  
  CONCLUSIONS
  Nonvital bleaching with 10% carbamide peroxide adversely affected the immediate sealing ability of resin composite restoration; both 10% sodium ascorbate treatment and a 1-week delay in restoration following bleaching improved the reduced sealing ability of resin composite.
authors.affiliation: Department of Restorative Dentistry and Endodontics, School of Dentistry, Ege University, Izmir, Turkey. mturkun@bornova.ege.edu.tr
authors.forename: M
authors.initials: M
authors.lastname: Türkün
authors.forename: L S
authors.initials: LS
authors.lastname: Türkün
mesh_terms: D000975:Antioxidants / Q000737:chemistry; D001205:Ascorbic Acid / Q000737:chemistry; D000077463:Carbamide Peroxide; D004396:Coloring Agents; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003763:Dental Leakage / Q000145:classification; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent; D017220:Dentin-Bonding Agents / Q000737:chemistry; D004338:Drug Combinations; D006801:Humans; D016877:Oxidants / Q000737:chemistry / Q000627:therapeutic use*; D010545:Peroxides / Q000737:chemistry / Q000627:therapeutic use*; D012390:Root Canal Therapy; D012464:Saliva, Artificial / Q000737:chemistry; D018709:Statistics, Nonparametric; D013499:Surface Properties; D013997:Time Factors; D014073:Tooth Bleaching / Q000379:methods*; D014508:Urea / Q000031:analogs & derivatives* / Q000737:chemistry / Q000627:therapeutic use*
chemical_list: D000975:Antioxidants; D004396:Coloring Agents; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D004338:Drug Combinations; D016877:Oxidants; D010545:Peroxides; D012464:Saliva, Artificial; D000077463:Carbamide Peroxide; D014508:Urea; D001205:Ascorbic Acid