title: Limited interaction of a self-adhesive flowable composite with dentin/enamel characterized by TEM.
abstract: A new category of composite which does not require any acid etching or bonding protocol prior to application has been introduced. The purpose of this study was to characterize the interfacial ultra-structure at enamel and dentin surfaces by means of transmission electron microscopy (TEM).
  
  
  
  Non-carious human third molars were randomly divided into 6 groups (bur-cut dentin, SiC-ground dentin, fractured dentin, bur-cut enamel, SiC-ground enamel, and un-cut enamel). After preparation of the respective surfaces, the self-adhesive flowable composite (Vertise Flow, Kerr) was applied. Non-demineralized/demineralized and non-stained/stained sections of 70-90nm were prepared following common TEM-specimen processing procedures. Additional specimens were immersed in an ammoniacal silver nitrate solution.
  
  
  
  The composite-dentin interface was free of voids and no de-bonding occurred during specimen preparation. For bur-cut and SiC-ground dentin, no surface demineralization was observed and the smear contained residual hydroxyapatite. On fractured dentin (i.e. without smear interference), a very thin interaction area of 100-200nm without apparent signs of surface demineralization was seen. When the composite was bonded to enamel, a distinct separation between the self-adhesive composite and enamel was present in all three groups. A tight interaction, yet without distinct dissolution of hydroxyapatite, could only be seen in some regions at bur-cut enamel where smear was absent or sparse. Silver nitrate infiltration was associated with the presence of smear.
  
  
  
  The self-adhesive composite showed limited interaction with smear-covered substrates and aprismatic enamel, which explains its inferior diminished bonding capacity in comparison with current adhesives.
authors.affiliation: KU Leuven (University of Leuven), Department of Oral Health Sciences, BIOMAT & University Hospitals Leuven, Dentistry, 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 (University of Leuven), Department of Oral Health Sciences, BIOMAT & University Hospitals Leuven, Dentistry, Leuven, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: De Munck
authors.affiliation: KU Leuven (University of Leuven), Department of Oral Health Sciences, BIOMAT & University Hospitals Leuven, Dentistry, Leuven, Belgium.
authors.forename: Annelies
authors.initials: A
authors.lastname: Van Ende
authors.affiliation: KU Leuven (University of Leuven), Department of Oral Health Sciences, BIOMAT & University Hospitals Leuven, Dentistry, Leuven, Belgium.
authors.forename: André
authors.initials: A
authors.lastname: Poitevin
authors.affiliation: Hokkaido University Graduate School of Dental Medicine, Department of Restorative Dentistry, Sapporo, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Matsumoto
authors.affiliation: Hokkaido University Graduate School of Dental Medicine, Department of Biomaterials and Bioengineering, Sapporo, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Yoshida
authors.affiliation: Okayama University Graduate School of Dentistry, Department of Fixed Prosthodontics, Okayama, Japan.
authors.forename: Takuo
authors.initials: T
authors.lastname: Kuboki
authors.affiliation: KU Leuven (University of Leuven), Department of Oral Health Sciences, BIOMAT & University Hospitals Leuven, Dentistry, Leuven, Belgium.
authors.forename: Kirsten L
authors.initials: KL
authors.lastname: Van Landuyt
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 (University of Leuven), Department of Oral Health Sciences, BIOMAT & University Hospitals Leuven, Dentistry, Leuven, Belgium. Electronic address: bart.vanmeerbeek@kuleuven.be.
authors.forename: Bart
authors.initials: B
authors.lastname: Van Meerbeek
mesh_terms: D000134:Acid Etching, Dental; D003188:Composite Resins; D001840:Dental Bonding; D003738:Dental Cements; D003743:Dental Enamel; D003804:Dentin; D017220:Dentin-Bonding Agents; D006801:Humans; D008422:Materials Testing; D008963:Molar; D019279:Resin Cements; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D003738:Dental Cements; D017220:Dentin-Bonding Agents; D019279:Resin Cements; C111840:flowable hybrid composite
keywords: Dental bonding; Nano-leakage; Resin-smear complex; Self-adhesive; Transmission electron microscopy