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Agreement Among International Periodontal Experts Using the 2017 World Workshop Classification of Periodontitis.

BACKGROUND
A new periodontitis classification was recently introduced involving multidimensional staging and grading. The Study's aim was to assess if individuals well-trained in periodontics consistently used the new classification for patients with severe periodontitis. The secondary goal was to identify "gray zones" related to classifications.


METHODS
Participants (raters) individually classified 10 pre-selected severe periodontitis cases using the 2017 World Workshop classification. An internet case-based study was conducted after inviting members from American Academy of Periodontology and European Federation of Periodontology. Gold-standard diagnoses were determined by five experts who developed the new periodontitis classification. Inter-reliability agreement among raters was assessed using Fleiss Kappa index with the jackknife method for linearly-weighted Kappa calculations. McNemar´s test was used to determine symmetry between raters and gold-standard panel.


RESULTS
103 raters participated and classified 9 clinical cases. Fleiss' Kappa values showed moderate inter-examiner consistency among raters for stage (K value: 0.49; 95%CI:0.19-0.79), grade (K value 0.50; 95%CI:0.30-0.70) and extent (K value: 0.51; 95%CI:0.23-0.77). When analyzed as composite (stage, grade, extent) a moderate inter-reliability was present among raters, k = 0.479 (K value: 0.47; 95%CI: 0.442 - 0.515). Agreement between raters and gold-standard panel was staging 76.6%; grading 82%; and extent 84.8%. In 6 of 9 cases 77-99% of raters consistently agreed with gold-standard panel, and other 3 cases had gray zone factors that reduced rater consistency.


CONCLUSION
Clinicians trained in the 2017 World Workshop periodontitis classification demonstrated moderate concordance in classifying 9 severe periodontitis cases, and in 6 of 9 cases raters consistently agreed with the gold-standard panel. This article is protected by copyright. All rights reserved.