title: Potential smear layer interference with bonding of self-etching adhesives to dentin.
abstract: OBJECTIVE
  To evaluate the effect of smear-layer interposition on the bonding effectiveness of self-etching adhesives with different etching potential.
  
  
  METHODS
  Bur-cut dentin specimens were obtained from 25 human molars after preparation of the dentin surface with a medium-grit diamond bur (bur-cut). An additional 25 molars were fractured at the midcoronal dentin to create a smear-layer-free surface (smear-free dentin). The prepared teeth were assigned to 5 groups, according to the adhesive to be applied: a strong one-step self-etching adhesive (PLP, Adper Prompt L-Pop, 3M ESPE, pH = 0.8); two ultra-mild one-step self-etching adhesives (C3S, Clearfil Tri-S Bond, Kuraray, pH = 2.7; AEB, Adper Easy Bond, 3M ESPE; pH = 2.7 ); as the self-etching control, a mild two-step self-etching adhesive (CSE, Clearfil SE Bond, Kuraray, pH of primer = 1.9); and as the etch-and-rinse control, a three-step etch-and-rinse adhesive (OFL, Optibond FL, Kerr). After composite buildups were made, all specimens were stored in distilled water (24 h/37°C) prior to microtensile bond strength testing (µTBS). The failure mode was determined with a stereomicroscope at 50X magnification. Representative µTBS specimens were processed for analysis in a Feg-SEM. The Kruskal-Wallis test was performed to determine statistical differences (p < 0.05).
  
  
  RESULTS
  Except for the strong one-step self-etching adhesive, all other self-etching adhesives (mild and ultramild) revealed a significantly lower bond strength to bur-cut dentin than to smear-free dentin. The etch-and-rinse adhesive presented the highest µTBS, which was not significantly different when bonded to bur-cut or smear-free dentin. Fracture analysis demonstrated a prevalence of adhesive failures for the self-etching adhesives, while OFL revealed more mixed failures. SEM revealed that smear debris remained part of the adhesive interfacial complex produced by the ultra-mild one-step self-etching adhesive C3S when applied on bur-cut dentin.
  
  
  CONCLUSIONS
  Smear debris interferes with the interaction of mild and ultra-mild self-etching adhesives with dentin.
authors.affiliation: Department of Oral Health Sciences, University of Leuven, Leuven, Belgium.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Suyama
authors.forename: Anne-Katrin
authors.initials: AK
authors.lastname: Lührs
authors.forename: Jan
authors.initials: J
authors.lastname: De Munck
authors.forename: Atsushi
authors.initials: A
authors.lastname: Mine
authors.forename: André
authors.initials: A
authors.lastname: Poitevin
authors.forename: Toshimoto
authors.initials: T
authors.lastname: Yamada
authors.forename: Bart
authors.initials: B
authors.lastname: Van Meerbeek
authors.forename: Marcio Vivan
authors.initials: MV
authors.lastname: Cardoso
mesh_terms: D001840:Dental Bonding; D003737:Dental Cavity Preparation; D045662:Dental Etching; D003754:Dental High-Speed Equipment; D003799:Dental Stress Analysis; D003804:Dentin; D017220:Dentin-Bonding Agents; D006801:Humans; D019279:Resin Cements / Q000737:chemistry; D016369:Smear Layer; D013718:Tensile Strength
chemical_list: C438313:Clearfil SE Bond; C515604:Clearfil Tri-S Bond; D017220:Dentin-Bonding Agents; C092987:Optibond; C408584:Prompt L-Pop; D019279:Resin Cements