title: Antioxidant agents and their effects on shear bond strength of bleached enamel.
abstract: OBJECTIVE
  The goal of this study was to fnd a method to eliminate bond strength reduction after vital bleaching.
  
  
  METHODS
  Sixty fat surfaces of enamel central human incisors were prepared by diamond disks. In the frst group, the samples immediately bonded to the tooth after bleaching. For the second group, the bleached samples were treated by sodium ascorbate for 1 hours. In the third and fourth groups the treatment was down using a new antioxidant agent for 1 hour and 15 minutes respectively. For the ffth group no bleaching was done. Cylindrical composite resin (Z 100) with a Single Bond adhesive system was bonded to the enamel with a special metal mold. After thermocycling, the samples were loaded at a crosshead speed of 0.5 mm/min. The mode of failures was inspected by the Dino Lite microscope and the microstructure of the debonding surfaces was observed by SEM. Considering normal data, statistical analysis was conducted by ANOVA and Tukey tests (p = 0.05).
  
  
  RESULTS
  The fourth group had maximum (21.82), while the frst group had the least (9.0971) shear bond strength. The ANOVA test showed a signifcant difference among the fve groups (p = 0.0002). There was not any signifcant statistical difference between the three types of debonding (p = 0.165).
  
  
  CONCLUSIONS
  The usage of sodium ascorbate or sodium ascorbate with detergent after vital bleaching are effective methods for reducing the damaging effects of bleaching agents on the shear bond strength of composite resin restoration to enamel. CLINICAL SIGNIFCANCE: Using antioxidants is necessary post bleaching and before resin bonding.
authors.affiliation: Associate Professor, Dental Materials Research Center, Department of Operative Dentistry, Faculty of Dentistry, Mashhad University of Medical Sciences, Khorasan, Iran, e-mail:dentist_57@yahoo.com.
authors.forename: Horieh
authors.initials: H
authors.lastname: Moosavi
authors.affiliation: Professor, Dental Research Center, Department of Operative Dentistry Faculty of Dentistry, Mashhad University of Medical Sciences Khorasan, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Maleknejad
authors.affiliation: Resident, Dental Materials Research Center, Department of Operative Dentistry, Faculty of Dentistry, Mashhad University of Medical Sciences, Khorasan, Iran.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Hoseinipour
authors.affiliation: Resident, Department of Operative Dentistry, Dental Materials Research Center, Khorasan, Iran.
authors.forename: Lila
authors.initials: L
authors.lastname: Hatami
authors.affiliation: Resident, Department of Operative Dentistry, Dental Material Research Center, Faculty of Dentistry, Mashhad University of Medical Sciences, Khorasan, Iran.
authors.forename: Mahsa
authors.initials: M
authors.lastname: Zeynali
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D001205:Ascorbic Acid / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D000077463:Carbamide Peroxide; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure*; D003764:Dental Materials / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D003902:Detergents / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010545:Peroxides / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D033081:Shear Strength; D012822:Silicon Dioxide / Q000737:chemistry; D013314:Stress, Mechanical; D013696:Temperature; D013997:Time Factors; D014073:Tooth Bleaching; D058205:Tooth Bleaching Agents / Q000737:chemistry; D014508:Urea / Q000031:analogs & derivatives / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry
chemical_list: D000975:Antioxidants; D003188:Composite Resins; D003764:Dental Materials; D003902:Detergents; D010545:Peroxides; D019279:Resin Cements; D058205:Tooth Bleaching Agents; C083568:Z100 composite resin; C115612:single bond; D000077463:Carbamide Peroxide; D017438:Bisphenol A-Glycidyl Methacrylate; D012822:Silicon Dioxide; D014508:Urea; D015040:Zirconium; D001205:Ascorbic Acid