title: Can viscosity of acid etchant influence the adhesion of fibre posts to root canal dentine?
abstract: OBJECTIVE
  To evaluate the influence of acid viscosity, endodontic sealer and root canal region on the push-out bond strength of a glass fibre post.
  
  
  METHODS
  Seventy-eight single-rooted human teeth were selected (60 for push-out and 18 for scanning electron microscopy characterization, SEM, n = 13 per group). The root canals were prepared with a step-back technique and then filled with Endofill or AH Plus sealer. Teeth without root fillings were used as controls. The preparation of the post-space was to a length of 11 mm using standardized rotary instruments. The root dentine was treated with 37% phosphoric acid (gel or liquid). The fibre posts (Reforpost) were silanized, and resin cement (Enforce) was used for luting procedures. Each root was cross-sectioned, and samples from the cervical and apical regions were subjected to a push-out bond strength test. Specimens from each group were sectioned longitudinally and subjected to SEM characterization for the dentine/cement/post interface. Statistical analysis for push-out tests was carried out using factorial anova followed by Tukey's test (P < 0.05).
  
  
  RESULTS
  The three factors under evaluation (acid, endodontic sealer and region) and their interaction significantly influenced bond strength values (P < 0.05). In general, liquid phosphoric acid had significantly higher bond strength values in the apical region (P < 0.05), with hybrid layer formation, while endodontic sealers reduced bond strength values compared to the control (P < 0.05).
  
  
  CONCLUSIONS
  The use of a liquid acid etchant created higher bond strength values in the apical region.
authors.affiliation: School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil.
authors.forename: M M S
authors.initials: MM
authors.lastname: Salas
authors.forename: J S
authors.initials: JS
authors.lastname: Bocangel
authors.forename: S
authors.initials: S
authors.lastname: Henn
authors.forename: T
authors.initials: T
authors.lastname: Pereira-Cenci
authors.forename: M S
authors.initials: MS
authors.lastname: Cenci
authors.forename: E
authors.initials: E
authors.lastname: Piva
authors.forename: F F
authors.initials: FF
authors.lastname: Demarco
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods*; D000704:Analysis of Variance; D001840:Dental Bonding; D017268:Dental Prosthesis Retention; D003786:Dental Pulp Cavity / Q000187:drug effects / Q000648:ultrastructure*; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent; D003799:Dental Stress Analysis; D003804:Dentin / Q000187:drug effects / Q000648:ultrastructure*; D020878:Device Removal; D004853:Epoxy Resins / Q000494:pharmacology; D005782:Gels; D006801:Humans; D010756:Phosphoric Acids / Q000737:chemistry; D011176:Post and Core Technique / Q000295:instrumentation; D012387:Root Canal Filling Materials / Q000494:pharmacology; D018915:Root Canal Preparation / Q000379:methods*; D014783:Viscosity
chemical_list: D004853:Epoxy Resins; D005782:Gels; D010756:Phosphoric Acids; D012387:Root Canal Filling Materials; C534916:epoxy resin-based root canal sealer; C074417:Endo-Fill; C030242:phosphoric acid