title: Dentin-smear remains at self-etch adhesive interface.
abstract: OBJECTIVE
  The bonding potential of 'mild' self-etch adhesives may be compromised due to smear interference, as they may not dissolve/penetrate the smear layer effectively due to their relatively low acidity. We observed that the thickness of the dentin smear layer differed depending on the surface-preparation methodology used.
  
  
  METHODS
  The interaction of an (ultra-)mild self-etch adhesive (Clearfil S3 Bond, Kuraray Noritake) with human dentin, prepared either using a medium-grit diamond bur ('thick', clinically relevant smear layer) or 600-grit SiC-paper ('thin' smear layer), or just fractured (smear-free), was evaluated using high-resolution transmission electron microscopy (TEM). Non-demineralized/demineralized 30-100nm interfacial cross-sections were prepared following common TEM-specimen processing and diamond-knife ultra-microtomy.
  
  
  RESULTS
  The adhesive did not dissolve the bur-cut, nor the SiC-ground smear layer, but impregnated it. Within this 'resin-smear complex', hydroxyapatite was abundantly present. At fractured dentin, this complex was not present, while the actual layer of interaction of the adhesive was limited to about 100nm. Non-demineralized 'ultra-thin' (30-50nm) sections confirmed the interfacial ultra-structure to differ for the three surface-preparation methods. An electron dense band was consistently disclosed at the adhesive interface, most likely representing the documented chemical interaction of the functional monomer 10-MDP with Ca.
  
  
  CONCLUSIONS
  The dentin surface-preparation method significantly affects the nature of the smear layer and the interaction with the ultra-mild self-etch adhesive.
authors.affiliation: KU Leuven BIOMAT, Department of Oral Health Sciences, KU Leuven (University of Leuven), Leuven, Belgium; Department of Fixed Prosthodontics, Osaka University Graduate School of Dentistry, Osaka, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Mine
authors.affiliation: KU Leuven BIOMAT, Department of Oral Health Sciences, KU Leuven (University of Leuven), Leuven, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: De Munck
authors.affiliation: KU Leuven BIOMAT, Department of Oral Health Sciences, KU Leuven (University of Leuven), Leuven, Belgium.
authors.forename: Marcio Vivan
authors.initials: MV
authors.lastname: Cardoso
authors.affiliation: KU Leuven BIOMAT, Department of Oral Health Sciences, KU Leuven (University of Leuven), Leuven, Belgium.
authors.forename: Kirsten L
authors.initials: KL
authors.lastname: Van Landuyt
authors.affiliation: KU Leuven BIOMAT, Department of Oral Health Sciences, KU Leuven (University of Leuven), Leuven, Belgium.
authors.forename: André
authors.initials: A
authors.lastname: Poitevin
authors.affiliation: KU Leuven BIOMAT, Department of Oral Health Sciences, KU Leuven (University of Leuven), Leuven, Belgium.
authors.forename: Annelies
authors.initials: A
authors.lastname: Van Ende
authors.affiliation: Department of Fixed Prosthodontics, Osaka University Graduate School of Dentistry, Osaka, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Matsumoto
authors.affiliation: Department of Biomaterials and Bioengineering, Hokkaido University Graduate School of Dental Medicine, Sapporo, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Yoshida
authors.affiliation: Department of Oral Rehabilitation and Regenerative Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
authors.forename: Takuo
authors.initials: T
authors.lastname: Kuboki
authors.affiliation: Department of Fixed Prosthodontics, Osaka University Graduate School of Dentistry, Osaka, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Yatani
authors.affiliation: KU Leuven BIOMAT, Department of Oral Health Sciences, KU Leuven (University of Leuven), Leuven, Belgium. Electronic address: bart.vanmeerbeek@med.kuleuven.be.
authors.forename: Bart
authors.initials: B
authors.lastname: Van Meerbeek
mesh_terms: D003738:Dental Cements; D045662:Dental Etching; D003804:Dentin; D006801:Humans; D066298:In Vitro Techniques; D046529:Microscopy, Electron, Transmission
chemical_list: D003738:Dental Cements
keywords: Adhesion; Hybrid layer; Mild self-etch; Resin-smear complex; Smear layer; TEM