Intra‐ and inter‐examiner reliability in classifying periodontitis according to the 2018 classification of periodontal diseases

AIM: To evaluate the inter-examiner reliability in classifying periodontitis using the 2018 classification of periodontal diseases, when used by postgraduate students, academics, and specialist clinicians trained in European Federation of Periodontology (EFP) and American Academy of Periodontology (AAP) postgraduate-accredited programmes. MATERIALS AND METHODS: An online survey including five patients with periodontitis was sent twice to seven specialists in periodontology to provide the staging and grading characteristics. After agreeing on a "gold-standard" classification, the same questionnaire was sent to 16 EFP and 73 AAP postgraduate programmes, to be answered by their faculty, graduates, and students. The responses were compared with the gold-standard classification, and the inter-examiner agreement was calculated. RESULTS: One-hundred and seventy-four participants completed the survey. The inter-examiner agreement resulted in 68.7% in assigning the stage, 82.4% in assigning the grade, and 75.5% in assigning the extent. The academic position and the experience of the participants did not have any significant influence on classifying periodontitis as the gold standard. CONCLUSIONS: The use of the 2018 periodontitis classification resulted in high inter-examiner reliability when used by a specialist group of clinicians, postgraduate students, and academicians, irrespective of their current position and experience. Given the low response rate and potential selection bias, results pertaining to the use of this system in classifying periodontitis should be interpreted with caution.