title: Interrater and intrarater reliability of FDI criteria applied to photographs of posterior tooth-colored restorations.
abstract: BACKGROUND
  Since 2007, the FDI World Dental Federation (FDI) criteria have been used for the clinical evaluation of dental restorations. However, the reliability of the FDI criteria has not been sufficiently addressed.
  
  
  OBJECTIVE
  The purpose of this study was to assess and compare the interrater and intrarater reliability of the FDI criteria by evaluating posterior tooth-colored restorations photographically.
  
  
  METHODS
  A total of 160 clinical photographs of posterior tooth-colored restorations were evaluated independently by 5 raters with 9 of the FDI criteria suitable for photographic evaluation. The raters recorded the score of each restoration by using 5 grades, and the score was dichotomized into the clinical evaluation scores. After 1 month, 2 of the raters reevaluated the same set of 160 photographs in random order. To estimate the interrater reliability among the 5 raters, the proportion of agreement was calculated, and the Fleiss multirater kappa statistic was used. For the intrarater reliability, the proportion of agreement was calculated, and the Cohen standard kappa statistic was used for each of the 2 raters.
  
  
  RESULTS
  The interrater proportion of agreement was 0.41 to 0.57, and the kappa value was 0.09 to 0.39. Overall, the intrarater reliability was higher than the interrater reliability, and rater 1 demonstrated higher intrarater reliability than rater 2. The proportion of agreement and kappa values increased when the 5 scores were dichotomized. The reliability was relatively lower for the esthetic properties compared with the functional or biological properties.
  
  
  CONCLUSIONS
  Within the limitations of this study, the FDI criteria presented slight to fair interrater reliability and fair to excellent intrarater reliability in the photographic evaluation of posterior tooth-colored restorations. The reliability was improved by simplifying the evaluation scores.
authors.affiliation: Clinical Research Assistant Professor, Department of Conservative Dentistry and Oral Science Research Center, Yonsei University College of Dentistry, Seoul, Republic of Korea.
authors.forename: Dohyun
authors.initials: D
authors.lastname: Kim
authors.affiliation: Graduate student, Department of Conservative Dentistry and Oral Science Research Center, Yonsei University College of Dentistry, Seoul, Republic of Korea.
authors.forename: So-Yeon
authors.initials: SY
authors.lastname: Ahn
authors.affiliation: Graduate student, Department of Conservative Dentistry and Oral Science Research Center, Yonsei University College of Dentistry, Seoul, Republic of Korea.
authors.forename: Junyoung
authors.initials: J
authors.lastname: Kim
authors.affiliation: Professor, Department of Conservative Dentistry and Oral Science Research Center, Yonsei University College of Dentistry, Seoul, Republic of Korea. Electronic address: sunghopark@yuhs.ac.
authors.forename: Sung-Ho
authors.initials: SH
authors.lastname: Park
mesh_terms: D003793:Dental Restoration, Permanent; D004955:Esthetics, Dental; D006801:Humans; D015588:Observer Variation; D010781:Photography / Q000379:methods* / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D056910:Republic of Korea; D012107:Research Design; D014075:Tooth Discoloration / Q000000981:diagnostic imaging*