title: Transmission electron microscopic examination of the interface between a resin-modified glass-ionomer and Er:YAG laser-irradiated dentin.
abstract: OBJECTIVE
  The aim of this study was to analyze the ultrastructural characteristics of the interface between a resin-modified glass ionomer (RMGI) and Er:YAG laser-irradiated dentin.
  
  
  BACKGROUND
  The Er:YAG laser has been considered as a possible alternative for cavity preparation, but the interaction between glass ionomers and Er:YAG-lased dentin still needs further investigation.
  
  
  METHODS
  Five dentin surfaces were prepared by diamond bur (120,000 rpm) as controls or for Er:YAG laser irradiation (31.45 J/cm(2), 200 mJ, 10 Hz, 100 micros). The RMGI Fuji II LC (GC) was then applied to their surfaces, which were previously conditioned with a 20% polyalkenoic acid conditioner. The samples were sealed with an unfilled resin, stored in distilled water for 1 wk at 37 degrees C, and then processed for transmission electron microscopic (TEM) examination.
  
  
  RESULTS
  When applied to bur-cut dentin (controls), Fuji II LC was able to partially demineralize the dentin surface, resulting in the formation of a hybrid layer, on top of which a sub-micron gel-phase was observed. In the laser-irradiated samples, the RMGI was in close contact with the irregular dentin substrate, but no hybrid layer or gel-phase formation could be detected, nor were there signs of dentin demineralization or collagen melting. Horizontal cracks were clearly seen in the sub-surface layer of dentin.
  
  
  CONCLUSIONS
  Although presenting horizontal micro-cracks in its sub-surface, the irregular laser-irradiated dentin showed close contact with the RMGI. However, no hybrid layer or gel-phase could be detected, and there were no signs of dentin demineralization and collagen melting.
authors.affiliation: Department of Operative Dentistry and Endodontology, Ghent Dental Laser Center, Dental School, Ghent University, Ghent, Belgium. katleen.delme@ugent.be
authors.forename: Katleen I M
authors.initials: KI
authors.lastname: Delmé
authors.forename: Marcio Vivan
authors.initials: MV
authors.lastname: Cardoso
authors.forename: Atsushi
authors.initials: A
authors.lastname: Mine
authors.forename: Roeland J G
authors.initials: RJ
authors.lastname: De Moor
authors.forename: Bart
authors.initials: B
authors.lastname: Van Meerbeek
mesh_terms: D003764:Dental Materials / Q000494:pharmacology; D003804:Dentin / Q000187:drug effects* / Q000528:radiation effects* / Q000648:ultrastructure; D005899:Glass Ionomer Cements / Q000494:pharmacology*; D006801:Humans; D053844:Lasers, Solid-State; D028022:Low-Level Light Therapy; D046529:Microscopy, Electron, Transmission; D012117:Resins, Synthetic / Q000494:pharmacology*
chemical_list: D003764:Dental Materials; C079765:Fuji II LC cement; D005899:Glass Ionomer Cements; D012117:Resins, Synthetic