title: Bonding of an auto-adhesive luting material to enamel and dentin.
abstract: OBJECTIVE
  The objectives of this study were (1) to assess the bonding performance of a new auto-adhesive cement (RelyX Unicem, 3M ESPE) to enamel and dentin, using a standard micro-tensile bond strength (microTBS) test set-up, and (2) to evaluate the interaction of this material with dentin by means of high-resolution electron microscopy.
  
  
  METHODS
  The microTBS of RelyX Unicem with and without prior acid etching was determined to enamel and dentin after 24 h of water storage and compared to the bonding effectiveness of the control cement (Panavia-F, Kuraray). In addition, diamond-knife cut interfaces of RelyX Unicem and Panavia-F bonded to dentin were examined using field-emission scanning (Fe-SEM) and transmission electron microscopy (TEM).
  
  
  RESULTS
  The microTBS of RelyX Unicem to enamel was significantly lower than that of the control cement, whereas no significant difference was found when both cements were bonded to dentin. Acid etching prior to the application of RelyX Unicem raised the enamel microTBS to the same level as that of the control, but was detrimental for the dentin bonding effectiveness. The latter must be attributed to inadequate infiltration of the collagen mesh as revealed by Fe-SEM and TEM. Morphological evaluation additionally revealed that RelyX Unicem only superficially interacted with enamel and dentin, and that application using some pressure is required to ensure close adaptation of the cement to the cavity wall.
  
  
  CONCLUSIONS
  (1) RelyX Unicem should always be applied with some pressure, to ensure that the relatively high viscous cement intimately adapts to the cavity wall; (2) The cement only interacted superficially with dentin and enamel; (3) The best bonding effectiveness with this new auto-adhesive cement was obtained by selectively acid-etching enamel prior to luting.
authors.affiliation: Leuven BIOMAT Research Cluster, Department of Conservative Dentistry, School of Dentistry, Oral Pathology and Maxillo-facial Surgery, Catholic University of Leuven, Kapucijnenvoer 7, Leuven 3000, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: De Munck
authors.forename: Marcos
authors.initials: M
authors.lastname: Vargas
authors.forename: Kirsten
authors.initials: K
authors.lastname: Van Landuyt
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Hikita
authors.forename: Paul
authors.initials: P
authors.lastname: Lambrechts
authors.forename: Bart
authors.initials: B
authors.lastname: Van Meerbeek
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D002484:Cementation; D001840:Dental Bonding; D003743:Dental Enamel; D003799:Dental Stress Analysis; D003804:Dentin; D017220:Dentin-Bonding Agents; D019544:Equipment Failure Analysis; D006801:Humans; D008422:Materials Testing; D008854:Microscopy, Electron; D008963:Molar; D019279:Resin Cements; D013718:Tensile Strength; D014783:Viscosity; D014867:Water
chemical_list: D017220:Dentin-Bonding Agents; C438843:Panavia-Fluoro; C483701:Rely X Unicem; D019279:Resin Cements; D014867:Water