title: A radiographic and scanning electron microscopic study of approximal margins of Class II resin composite restorations placed in vivo.
abstract: BACKGROUND
  Clinical studies on the quality of Class II amalgam and resin composite restorations frequently report defective cervical margins.
  
  
  OBJECTIVE
  The aim of this study was to evaluate the quality of the approximal margins of Class II resin composite restorations placed in vivo using various application techniques and adhesive systems.
  
  
  METHODS
  Class II restorations were placed in premolar teeth in vivo, using different adhesive systems and application techniques. After extraction of the teeth, the restorations were evaluated radiographically and by SEM.
  
  
  RESULTS
  One-hundred and forty-four resin composite Class II restorations were evaluated. According to the radiographs, 4% of the restorations were overfilled and 33% were underfilled. SEM pictures revealed that 43% of the restorations were overfilled and 25% underfilled. Thirty-two per cent of the restored teeth showed a flash of bonding agent on the approximal surface.
  
  
  CONCLUSIONS
  Class II resin composite restorations placed in vivo may be found frequently to show imperfect cervical margins. Overextended margins observed by SEM are difficult to detect on radiographs. When seen on a radiograph, a thick layer of bonding agent may be interpreted as an underfilled restoration.
authors.affiliation: Department of Cariology and Endodontology, University of Nijmegen, The Netherlands. n.opdam@dent.kun.nl
authors.forename: N J
authors.initials: NJ
authors.lastname: Opdam
authors.forename: F J
authors.initials: FJ
authors.lastname: Roeters
authors.forename: A J
authors.initials: AJ
authors.lastname: Feilzer
authors.forename: I
authors.initials: I
authors.lastname: Smale
mesh_terms: D000134:Acid Etching, Dental; D000269:Adhesives / Q000737:chemistry; D000293:Adolescent; D000704:Analysis of Variance; D001641:Bicuspid / Q000000981:diagnostic imaging / Q000648:ultrastructure; D003188:Composite Resins / Q000737:chemistry*; D003723:Dental Amalgam / Q000737:chemistry; D001840:Dental Bonding; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent / Q000145:classification* / Q000379:methods; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D011859:Radiography; D019279:Resin Cements / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000269:Adhesives; C112274:Clearfil Liner Bond 2; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D019279:Resin Cements; C084018:Scotchbond Multi-Purpose; C074669:Clearfil Photo Bond; C084849:Clearfil Ray Posterior; D003723:Dental Amalgam