title: Hybrid layers of etch-and-rinse versus self-etching adhesive systems.
abstract: OBJECTIVE
  To evaluate the effectiveness in the formation of resin tags, adhesive lateral branches and hybrid layers of five adhesive systems, when bonding to dentine.
  
  
  METHODS
  Flat dentin surfaces from 25 molars were bonded with several adhesive systems according to the manufacturers' instructions. Composite build-ups were constructed incrementally with Tetric Ceram. The Specimens were sectioned parallel to the long axis. One section was treated with phosphoric acid and sodium hypochlorite in order to reveal the hybrid layer formation. The other section was stored in 30% hydrochloric acid to detect resin tags and adhesive lateral branch formation.
  
  
  RESULTS
  The two etch-and-rinse self-priming adhesives exhibited thicker hybrid layers than those found in self-etching adhesive systems. The all-in-one adhesive showed droplet formation between the adhesive and the resin composite. The resin tags formed with the etch-and-rinse adhesives were much longer than those found with the self-etching adhesives. Lateral branch formation was observed in etch-and-rinse adhesives and in one of the self-etch adhesives Clearfil SE Bond (SEB).
  
  
  CONCLUSIONS
  The formed hybrid layer obtained with the two-step self-etching adhesives and the etch-and-rinse systems were continuous and uniform in thickness. Droplets within the all-in-one adhesive layer may occur as a result of water absorption from dentin through osmosis, and may interfere with proper resin polymerization. Resin tags obtained with SEB and the etch-and-rinse adhesive systems showed lateral branches, which is a sign of proper resin infiltration.
authors.affiliation: Faculty of Dentistry, University of Salamanca, Salamanca, Spain. albertoalbaladejo@usal.es
authors.forename: Alberto
authors.initials: A
authors.lastname: Albaladejo
authors.forename: Raquel
authors.initials: R
authors.lastname: Osorio
authors.forename: Manuel
authors.initials: M
authors.lastname: Toledano
authors.forename: Marco
authors.initials: M
authors.lastname: Ferrari
mesh_terms: D001840:Dental Bonding; D003738:Dental Cements; D045662:Dental Etching / Q000379:methods; D006801:Humans; D008855:Microscopy, Electron, Scanning
chemical_list: D003738:Dental Cements