title: Shear bond strength of one-step self-etch adhesives to enamel: effect of acid pretreatment.
abstract: OBJECTIVE
  The purposes of this study were to evaluate the effect of surface pretreatment with phosphoric acid on the enamel bond strength of four-one-step self-etch adhesives with different pH values.
  
  
  METHODS
  One hundred bovine permanent mandibular incisors were used. The materials used in this study included four-one-step self-etch adhesives with different pH values: Adper(™) Easy Bond Self-Etch Adhesive (ph = 0,8-1), Futurabond NR (ph = 1,4), G-aenial Bond (ph = 1,5), Clearfil(3) S Bond (ph = 2,7). One two-step self-etch adhesive (Clearfil SE Bond/ph = 0,8-1) was used as control. The teeth were assigned into two subgroups according to bonding procedure. In the first subgroup (n = 50), no pretreatment agent was applied. In the second subgroup (n = 50), etching was performed using 37% phosphoric acid for 30 s. After adhesive systems application, a nanohybrid composite resin was inserted into the enamel surface. The specimens were placed in a universal testing machine (Model 3343, Instron Corp., Canton, Mass., USA). After the testing procedure, the fractured surfaces were examined with an optical microscope at a magnification of 10× to determine failure modes. The adhesive remnant index (ARI) was used to assess the amount of adhesive left on the enamel surface.
  
  
  RESULTS
  Descriptive statistics of the shear bond strength and frequency distribution of ARI scores were calculated.
  
  
  CONCLUSIONS
  Enamel pretreatment with phosphoric acid significantly increased bond strength values of all the adhesives tested. No significant differences in bond strength were detected among the four different one-step self-etch adhesives with different pH. Two-step self-etch adhesive showed the highest bond strength.
authors.affiliation: Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, University of Pavia, Pavia, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Poggio
authors.forename: Andrea
authors.initials: A
authors.lastname: Scribante
authors.forename: Federica
authors.initials: F
authors.lastname: Della Zoppa
authors.forename: Marco
authors.initials: M
authors.lastname: Colombo
authors.forename: Riccardo
authors.initials: R
authors.lastname: Beltrami
authors.forename: Marco
authors.initials: M
authors.lastname: Chiesa
mesh_terms: D000134:Acid Etching, Dental; D000818:Animals; D002417:Cattle; D003738:Dental Cements; D003743:Dental Enamel; D033081:Shear Strength
chemical_list: D003738:Dental Cements
keywords: phosphoric acid pretreatment; self-etch adhesives; shear bond strength test