title: Etching a fiber post surface with high-concentration bleaching agents.
abstract: BACKGROUND
  Commonly, resin composites/cements fail to achieve proper bonding to fiber posts when their surfaces have not been previously etched. This study evaluated the effect of the concentration and application mode of hydrogen peroxide on the surface topography and bond strength of resin composite to glass-fiber posts.
  
  
  METHODS
  Fiber posts were immersed in 24% or 35% solutions (a high-concentration bleaching agent) of hydrogen peroxide (H2O2), or these solutions were applied over the post surface using a microbrush (n=10). Posts without any treatment were used as a control. After etching, the posts were silanated and an adhesive was applied. The posts were positioned in a mold, and a resin composite was incrementally inserted and light-cured. The post/resin assembly was serially sectioned into several beams that were subjected to a tensile bond strength test. The data were subjected to the two-way analysis of variance and Tukey test (α=0.05). The Dunnet's test was used to compare the experimental conditions to the control. The surface topography was analyzed using scanning electronic microscopy.
  
  
  RESULTS
  The non-etched post presented a relatively smooth surface without fiber exposure. Except for the application of 24% H2O2, the other experimental conditions increased the number of exposed fibers and bond strength in relation to the control. Although immersion resulted in higher values for the 24% H2O2 application, the mode of application did not alter bond strength when 35% H2O2 was used.
  
  
  CONCLUSIONS
  The effect of the mode of application of H2O2 depended on its level of concentration. A high-concentration bleaching agent improved the bond strength of the resin composite to the post surface, regardless of which mode was used.
authors.forename: M S
authors.initials: MS
authors.lastname: Menezes
authors.forename: A L
authors.initials: AL
authors.lastname: Faria-e-Silva
authors.forename: F P
authors.initials: FP
authors.lastname: Silva
authors.forename: G R
authors.initials: GR
authors.lastname: Reis
authors.forename: C J
authors.initials: CJ
authors.lastname: Soares
authors.forename: T H S
authors.initials: TH
authors.lastname: Stape
authors.forename: L R
authors.initials: LR
authors.lastname: Martins
mesh_terms: D003188:Composite Resins / Q000627:therapeutic use; D001840:Dental Bonding / Q000379:methods / Q000592:standards; D045662:Dental Etching / Q000379:methods*; D003799:Dental Stress Analysis; D005898:Glass; D006801:Humans; D006861:Hydrogen Peroxide / Q000627:therapeutic use; D008854:Microscopy, Electron; D011176:Post and Core Technique; D013499:Surface Properties; D058205:Tooth Bleaching Agents / Q000627:therapeutic use*
chemical_list: D003188:Composite Resins; D058205:Tooth Bleaching Agents; C009753:fiberglass; D006861:Hydrogen Peroxide