title: Bond strength of restorative material to dentin submitted to bleaching and Er:YAG laser post-treatment.
abstract: OBJECTIVE
  The purpose of this study was to assess the bond strength of a restorative material to bleached dentin, pretreated with Er:YAG laser.
  
  
  BACKGROUND
  Laser irradiation for dental surface treatment may increase the bond strength of restorative material to tooth surface. There are no reports of using Er:YAG laser on dentin bleached with 35% hydrogen peroxide.
  
  
  METHODS
  Forty maxillary canines were sectioned, resulting in 80 fragments (5×5 mm) of intracoronary dentin that were divided into eight groups (n=10) according to the dental bleaching (present or not), surface conditioning (with or without laser) and the post-bleaching time to perform restoration (immediately or 7 days). The bleached specimens received two applications of 38% hydrogen peroxide. Er:YAG laser was applied for 20 sec with 400 mJ/15 Hz. Restorative procedure was performed using phosphoric acid, an adhesive system, and resin using a split Teflon matrix. The specimens were submitted to shear bond strength test and the data (MPa) were analyzed by ANOVA and Tukey's test (α=0.05).
  
  
  RESULTS
  There were significant differences among the three factors (p<0.05). The highest values were obtained for unbleached specimens compared with bleached, for those treated with laser compared with those only conditioned with acid, and for those restored after 7 days compared with those having immediate restoration. In the interaction of factors, the bleached specimens treated with laser and restored immediately were statistically similar (p>0.05) to those bleached and restored after 7 days.
  
  
  CONCLUSIONS
  Er:YAG laser can restore the bond strength of the dentin/restorative material interface even if the restoration is performed immediately after bleaching.
authors.affiliation: School of Dentistry, University of Ribeirão Preto , Ribeirão Preto, SP, Brazil .
authors.forename: Fabiana Almeida
authors.initials: FA
authors.lastname: Curylofo
authors.forename: Danielle Cristine Furtado
authors.initials: DC
authors.lastname: Messias
authors.forename: Yara T Correa
authors.initials: YT
authors.lastname: Silva-Sousa
authors.forename: Aline Evangelista
authors.initials: AE
authors.lastname: Souza-Gabriel
mesh_terms: D003481:Cuspid; D001840:Dental Bonding / Q000379:methods*; D003738:Dental Cements / Q000737:chemistry; D003799:Dental Stress Analysis; D003804:Dentin / Q000528:radiation effects*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D004338:Drug Combinations; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D066298:In Vitro Techniques; D053844:Lasers, Solid-State; D055115:Light-Curing of Dental Adhesives; D010545:Peroxides / Q000737:chemistry; D011145:Polyvinyls / Q000737:chemistry; D013499:Surface Properties; D014073:Tooth Bleaching; D014508:Urea / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: C554641:Adper single bond 2; D003738:Dental Cements; D017220:Dentin-Bonding Agents; D004338:Drug Combinations; D010545:Peroxides; D011145:Polyvinyls; C093177:tooth-bleaching agent, Opalescence; D014508:Urea; D006861:Hydrogen Peroxide