title: Observer variation in the assessment of resin composite.
abstract: OBJECTIVE
  The aim of this study was to compare the type of information obtained from log-linear modelling vs Cohen's kappa statistics on observer variation in the assessment of marginal adaptation in composite inlays and amalgam restorations.
  
  
  METHODS
  Marginal adaptation of Class II resin composite inlays and amalgam restorations was clinically assessed by two observers, four years after placement. Each of 52 patients received 4 different restorations, three composite (Herculite XR, Clearfil CR Inlay and Visiomolar) inlays and one Tytin restoration. The results were evaluated by Cohens Kappa statistics and log-linear modelling.
  
  
  RESULTS
  The overall Cohen's kappa was 0.45, ranging from poor to good for the four materials. Log-linear modelling confirmed that the observers agreed beyond chance but this agreement depended on the performance of the material. Marginal adaptation of Visiomolar (ESPE) inlays was somewhat inferior compared to the other materials. The assessment of Clearfil CR (Kuraray) inlay was difficult using this clinical evaluation procedure.
  
  
  CONCLUSIONS
  Using log-linear modelling it is possible to look at observer agreement and material performance at the same time. This combined approach is important because agreement may depend on material performance.
authors.affiliation: Academic Centre for Dentistry Amsterdam (ACTA), Dept. of Cariology Endodontology and Pedodontics, The Netherlands. H.Tobi@acta.nl
authors.forename: H
authors.initials: H
authors.lastname: Tobi
authors.forename: H J
authors.initials: HJ
authors.lastname: Groen
authors.forename: C M
authors.initials: CM
authors.lastname: Kreulen
authors.forename: W E
authors.initials: WE
authors.lastname: van Amerongen
mesh_terms: D016009:Chi-Square Distribution; D003188:Composite Resins; D018849:Controlled Clinical Trials as Topic; D003723:Dental Amalgam; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent / Q000592:standards*; D006801:Humans; D007284:Inlays; D016013:Likelihood Functions; D016014:Linear Models; D015233:Models, Statistical; D015588:Observer Variation