title: Effect of different adhesion strategies on fiber post cementation: Push-out test and scanning electron microscopy analysis.
abstract: OBJECTIVE
  The aim of this study was to investigate the effect of phosphoric acid etching and the dentin pre-treatment with sodium hypochlorite (NaOCl) on the push-out bond strength between fiber post and root canal dentin.
  
  
  METHODS
  Root canals of 48 human incisors were selected, post spaces were prepared and assigned to four groups: G1-37% phosphoric acid (15 s); G2-5.25% NaOCl (2 min) +37% phosphoric acid (15 s); G3-37% phosphoric acid (60 s); and G4-5.25% NaOCl (2 min) +37% phosphoric acid (60 s). Fiber post cementation was performed with two-step etch-and-rinse adhesive system/dual-cured resin cement according to the manufacturer's recommendation. After 24 h, each root was sectioned transversally into three slices (cervical, middle and apical) and the bond strength of each section was determined using a push-out bond strength test. Morphology analysis of the bonded interface was evaluated using a scanning electron microscopy. Push-out strength data (MPa) were analyzed by Analysis of Variance and Tukey-Kramer (α = 0.05).
  
  
  RESULTS
  Considering the NaOCl pre-treatment, no statistically significant differences were observed among groups; however, when the phosphoric acid was applied during 60 s in the apical portion without NaOCl pre-treatment, the bond strength was statistically significant increased.
  
  
  CONCLUSIONS
  The NaOCl pre-treatment did not improve the bond strength of adhesive luting cement to root canal dentin. The findings suggest that the use of 37% phosphoric acid for 60 s may have a beneficial effect on bond strength in the apical root third.
authors.affiliation: Department of Clinical Dentistry, School of Dentistry, Federal University of Bahia, Salvador, BA, Brazil.
authors.forename: Letícia Oliveria
authors.initials: LO
authors.lastname: Saraiva
authors.affiliation: Department of Restorative Dentistry, College of Dentistry, University of Illinois at Chicago, Chicago, IL, USA.
authors.forename: Thaiane Rodrigues
authors.initials: TR
authors.lastname: Aguiar
authors.affiliation: Department of Integrated Clinic, School of Dentistry, Bahiana School of Medicine and Public Health, Salvador, BA, Brazil.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Costa
authors.affiliation: Department of Dental Materials and Pediatric Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Lourenço
authors.initials: L
authors.lastname: Correr-Sobrinho
authors.affiliation: Department of Integrated Clinic, School of Dentistry, Bahiana School of Medicine and Public Health, Salvador, BA, Brazil.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Muniz
authors.affiliation: Department of Clinical Dentistry, School of Dentistry, Federal University of Bahia, Salvador, BA, Brazil.
authors.forename: Paula
authors.initials: P
authors.lastname: Mathias
keywords: Dentin; fiber post; phosphoric acid; sodium hypochlorite