title: Experimental adhesives with different hydrophilicity: microshear test in after 1, 7, and 90 days' storage.
abstract: OBJECTIVE
  To assess the microshear bond strength of 3 experimental adhesives with different degrees of hydrophilicity after 1, 7 and 90 days of storage.
  
  
  METHODS
  The bonding effectiveness of three experimental two-step etch-and-rinse adhesives (bis- GMA, bis-EMA/bis-GMA, polybutadiene [C6H12]) and one commercial adhesive (Single Bond) to sound hydrated dentin was determined using the microshear test with delimitation of the adhesive area after 1, 7, and 90 days of storage in water at 37°C. Two-way ANOVA was performed at the 0.05 probability level. The fractures were classified as adhesive, cohesive in dentin, cohesive in resin, and mixed.
  
  
  RESULTS
  The experimental adhesives showed values in the range of 11.31 to 12.96 MPa, with polybutadiene (PBH) showing the lowest bond strengths, bis-GMA the highest, and bis-EMA/bis-GMA intermediary values. Single Bond yielded bond strengths of approximately 24 MPa. Water storage decreased the bond strength in all adhesives. Adhesive fractures were predominant in experimental adhesives, while mixed fractures were the most frequent type in the Single Bond group.
  
  
  CONCLUSIONS
  The experimental dentin adhesives of this study were able to form resin tags, but they could not penetrate into the collagen fibers and form hybrid layers. The resulting low bond strength decreased with increasing length of storage.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, Brazil. fredhori@usp.br
authors.forename: Frederico Seidi
authors.initials: FS
authors.lastname: Hori
authors.forename: Rubens Côrte
authors.initials: RC
authors.lastname: de Carvalho
mesh_terms: D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate; D002070:Butadienes; D003188:Composite Resins; D001840:Dental Bonding; D003799:Dental Stress Analysis; D003806:Dentin Permeability; D017220:Dentin-Bonding Agents / Q000737:chemistry; D004356:Drug Storage; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008422:Materials Testing; D033081:Shear Strength; D012995:Solubility
chemical_list: D002070:Butadienes; D003188:Composite Resins; D017220:Dentin-Bonding Agents; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate