title: Does active application of universal adhesives to enamel in self-etch mode improve their performance?
abstract: OBJECTIVE
  To evaluate the effect of adhesion strategy on the enamel microshear bond strengths (μSBS), etching pattern, and in situ degree of conversion (DC) of seven universal adhesives.
  
  
  METHODS
  84 extracted third molars were sectioned in four parts (buccal, lingual, proximal) and divided into 21 groups, according to the combination of the main factors adhesive (AdheSE Universal [ADU], All-Bond Universal [ABU], Clearfil Universal [CFU], Futurabond U [FBU], G-Bond Plus [GBP], Prime&Bond Elect (PBE), and Scotchbond Universal Adhesive [SBU]), and adhesion strategy (etch-and-rinse, active self-etch, and passive self-etch). Specimens were stored in water (37°C/24h) and tested at 1.0mm/min (μSBS). Enamel-resin interfaces were evaluated for DC using micro-Raman spectroscopy. The enamel-etching pattern was evaluated under a field-emission scanning electron microscope (direct and replica techniques). Data were analyzed with two-way ANOVA and Tukey's test (α=0.05).
  
  
  RESULTS
  Active self-etch application increased μSBS and DC for five out of the seven universal adhesives when compared to passive application (p<0.001). A deeper enamel-etching pattern was observed for all universal adhesives in the etch-and-rinse strategy. A slight improvement in etching ability was observed in active self-etch application compared to that of passive self-etch application. Replicas of GBP and PBE applied in active self-etch mode displayed morphological features compatible with water droplets. The DC of GBP and PBE were not affected by the application/strategy mode.
  
  
  CONCLUSIONS
  In light of the improved performance of universal adhesives when applied actively in SE mode, selective enamel etching with phosphoric acid may not be crucial for their adhesion to enamel.
  
  
  CONCLUSIONS
  The active application of universal adhesives in self-etch mode may be a practical alternative to enamel etching in specific clinical situations.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, State University of Ponta Grossa, Ponta Grossa, Paraná, Brazil.
authors.forename: Alessandro D
authors.initials: AD
authors.lastname: Loguercio
authors.affiliation: School of Dentistry, Universidad de Valparaíso, Valparaíso, Chile.
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Muñoz
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, State University of Ponta Grossa, Ponta Grossa, Paraná, Brazil; School of Dentistry, Universidad de Valparaíso, Valparaíso, Chile.
authors.forename: Issis
authors.initials: I
authors.lastname: Luque-Martinez
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, State University of Ponta Grossa, Ponta Grossa, Paraná, Brazil.
authors.forename: Viviane
authors.initials: V
authors.lastname: Hass
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, State University of Ponta Grossa, Ponta Grossa, Paraná, Brazil.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Reis
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, State University of Ponta Grossa, Ponta Grossa, Paraná, Brazil. Electronic address: perdi001@umn.edu.
authors.forename: Jorge
authors.initials: J
authors.lastname: Perdigão
mesh_terms: D000704:Analysis of Variance; D003738:Dental Cements / Q000737:chemistry; D003743:Dental Enamel / Q000737:chemistry / Q000648:ultrastructure; D045662:Dental Etching / Q000379:methods*; D019232:Dental Restoration Failure; D006801:Humans; D008855:Microscopy, Electron, Scanning; D008963:Molar / Q000737:chemistry / Q000648:ultrastructure; D010756:Phosphoric Acids / Q000008:administration & dosage; D011897:Random Allocation; D033081:Shear Strength; D013059:Spectrum Analysis, Raman; D014867:Water
chemical_list: D003738:Dental Cements; D010756:Phosphoric Acids; D014867:Water; C030242:phosphoric acid
keywords: Degree of conversion; Enamel; Etch-and-rinse; Microshear bond strength; Self-etch; Universal adhesive systems