title: Scanning electron microscopic evaluation of enamel surfaces exposed to 3 orthodontic bonding systems.
abstract: BACKGROUND
  This in-vitro study investigated the effects of conventional etching with a 35% phosphoric etching gel and priming/bonding with Transbond XT primer/adhesive (3M Unitek, Monrovia, Calif), conditioning with 10% polyacrylic acid and bonding with a resin-modified glass ionomer cement (Fuji ORTHO LC, GC Corporation, Tokyo Japan) or using a self-etching bonding system (Transbond Plus) and bonding with Transbond XT adhesive on the surface morphology of the enamel. The study was conducted at the Faculty of Dentistry, University of Oslo, in Norway, 2004.
  
  
  METHODS
  The enamel surfaces of extracted premolars where conditioned with 1 of the 3 systems and evaluated with environmental scanning electron microscope. Brackets were then bonded with 1 of 3 bonding agents and examined with a conventional scanning electron microscope.
  
  
  RESULTS
  The bonding systems induced different effects on the enamel structure. Phosphoric acid etching produced a rough, etched surface with the typical honeycomb pattern. Bonding brackets to such a surface resulted in thick resin tags relatively deep into the enamel. Less pronounced etching of the surface enamel was obtained by the self-etching primer system, and bonding resulted in smaller and fewer resin tags. The resin-modified glass ionomer bonded after conditioning the enamel with polyacrylic acid showed no resin tags.
  
  
  CONCLUSIONS
  Bonding systems with self-etching primers or conditioners with polyacrylic acid might offer potential benefits compared with conventional acid etching and priming because of fewer irreversible changes to the enamel surface.
authors.affiliation: Department of Orthodontics, Institute of Clinical Dentistry, Faculty of Dentistry, University of Oslo, Oslo, Norway.
authors.forename: Morten
authors.initials: M
authors.lastname: Fjeld
authors.forename: Bjørn
authors.initials: B
authors.lastname: Øgaard
mesh_terms: D000134:Acid Etching, Dental / Q000009:adverse effects* / Q000379:methods; D000180:Acrylic Resins / Q000009:adverse effects; D001641:Bicuspid; D003743:Dental Enamel / Q000473:pathology* / Q000648:ultrastructure; D005899:Glass Ionomer Cements / Q000009:adverse effects*; D006801:Humans; D008855:Microscopy, Electron, Scanning; D009967:Orthodontic Appliances; D010756:Phosphoric Acids / Q000009:adverse effects; D019279:Resin Cements / Q000009:adverse effects*
chemical_list: D000180:Acrylic Resins; D005899:Glass Ionomer Cements; D010756:Phosphoric Acids; D019279:Resin Cements; C429625:Transbond Plus Self-Etching Primer; C006903:carbopol 940; C030242:phosphoric acid