title: Inter-crystallite nanoretention of self-etching adhesives at enamel imaged by transmission electron microscopy.
abstract: The purpose of this in vitro study was to analyse the mode of action of self-etching adhesive systems when applied for resin-to-enamel bonding. Transmission electron microscopy was used to investigate the enamel-resin interface after application of non-rinsing self-etching adhesive systems based on phosphoric acid estered methacrylates (Clearfil Liner Bond 2, Clearfil SE Bond, Etch & Prime 3.0 and Resulcin AquaPrime) compared with conventional phosphoric acid etching and bonding (Heliobond). Non-decalcified ultrathin sections from the interface between enamel and self-etching adhesive systems revealed a 1.5-3.2-microm deep enamel surface layer characterized by a less-dense arrangement of enamel crystallites separated from each other by nanometer-sized spaces. A 1.5-3.2-microm wide, netlike resinous structure was observed in corresponding decalcified specimens, indicating that self-etching priming agents dissolve the peripheral and central part of the enamel crystallites, while simultaneously promoting inter- and intra-crystallite monomer infiltration. A similar pattern, but greater depth (6.9 microm) of enamel surface hybridization was found in the phosphoric acid-etched and bonded specimens. The nanoretentive interlocking between enamel crystallites and resin could explain the potential of self-etching adhesive systems in resin-to-enamel bonding despite the less distinct enamel etching pattern observed in scanning electron microscopy investigations.
authors.affiliation: Department of Operative Dentistry and Periodontology, Saarland University, Homburg/ Saar, Germany. zmkmhan@uniklinik-saarland.de
authors.forename: Matthias
authors.initials: M
authors.lastname: Hannig
authors.forename: Henning
authors.initials: H
authors.lastname: Bock
authors.forename: Burkard
authors.initials: B
authors.lastname: Bott
authors.forename: Wiebke
authors.initials: W
authors.lastname: Hoth-Hannig
mesh_terms: D000134:Acid Etching, Dental; D000179:Acrylates; D001840:Dental Bonding / Q000379:methods*; D003743:Dental Enamel / Q000648:ultrastructure; D003745:Dental Enamel Permeability; D011756:Diphosphates; D000431:Ethanol; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates; D008854:Microscopy, Electron; D019279:Resin Cements
chemical_list: D000179:Acrylates; C112274:Clearfil Liner Bond 2; C438313:Clearfil SE Bond; D011756:Diphosphates; C121187:Etch&Prime; D008689:Methacrylates; D019279:Resin Cements; C122122:Resulcin aquaPrime; D000431:Ethanol; C040415:heliobond