title: Microtensile bond strength of a nanofilled composite resin to human dentin after nonvital tooth bleaching.
abstract: OBJECTIVE
  The purpose of this in vitro study was to measure the microtensile bond strength of a nanofilled composite resin to human dentin after nonvital bleaching at different post-bleaching time intervals, and to analyze the fracture mode under SEM.
  
  
  METHODS
  Thirty-six sound human maxillary premolars extracted for orthodontic reasons were prepared in a standardized manner, and randomly assigned to four groups (n = 9): non bleached (control) (NB); bleached with sodium perborate and 35% hydrogen peroxide (SP-HP); bleached with 35% hydrogen peroxide (HP); and bleached with 37% carbamide peroxide (CP). Each group was subdivided into 3 subgroups (n = 3): restored immediately (RO); restored after 7 days (R7); and restored after 14 days (R14). The teeth were stored in distilled water for 24 h, sectioned 4 mm below cementoenamel junction, and the crown was serially sectioned to obtain sticks (0.9 mm2 cross section) for microtensile bond strength testing. The microTBS samples were attached to a universal testing machine (Instron, model 4444), using a Geraldeli's device. The test was performed until the fracture of the specimens, and all specimens were analyzed under a scanning electron microscope (Philips XL-30).
  
  
  RESULTS
  Two-way ANOVA (p = 0.05) revealed that there were no statistically significant differences of bond strength values for the bleaching agents used, or at different post-bleaching time intervals.
  
  
  CONCLUSIONS
  It was concluded that the definitive restoration can be accomplished immediately after nonvital bleaching treatment.
authors.affiliation: Department of Operative Dentistry, Federal University of Santa Catarina, Florianopolis, SC, Brazil. garcari@terra.com.br
authors.forename: Gilberto Müller
authors.initials: GM
authors.lastname: Arcari
authors.forename: Elito
authors.initials: E
authors.lastname: Araújo
authors.forename: Luiz Narciso
authors.initials: LN
authors.lastname: Baratieri
authors.forename: Guilherme Carpena
authors.initials: GC
authors.lastname: Lopes
mesh_terms: D000704:Analysis of Variance; D001641:Bicuspid; D017438:Bisphenol A-Glycidyl Methacrylate; D003188:Composite Resins; D001840:Dental Bonding; D003799:Dental Stress Analysis; D003804:Dentin; D017220:Dentin-Bonding Agents; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D053761:Nanocomposites; D019279:Resin Cements; D013718:Tensile Strength; D014073:Tooth Bleaching; D019553:Tooth, Nonvital
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; C474035:Filtek Supreme; D019279:Resin Cements; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate