Reliability of Sawai’s classification for dental cervical abrasions: A pilot study

AIM To test the reliability of the Sawai's classification for dental cervical abrasions. METHODS Intraoral photographs of 70 teeth from 23 patients with tooth abrasions were taken by the first examiner MS. The teeth were marked and the photos were maintained in a soft copy sequentially. Two other examiners FA and SC were trained in the use of the classification and any clarifications needed were provided at the beginning of the study. Each examiner was then given the soft copy of the complied photographs and was asked to classify the dental cervical abrasion according to their understanding of the Sawai's classification. They were given sheets to write their responses for every marked tooth. All the examiners were blinded to each other's observations which were then tested for inter-rater agreement among the three examiners. RESULTS The 70 teeth with tooth abrasions from 23 patients were examined by 3 investigators (MS, FA and SC) to test the reliability of the Sawai's classification system for tooth abrasion. Each examiner marked their responses in separate sheets which were blinded to each other. The kappa statistics were performed for inter-rater agreement among the three examiners. The level of agreement was evaluated according to the six-level nomenclature given by Landis and Koch. ICC and 95%CI between two examiners, i.e., the inter-rater agreement among 1st examiner (MS) and 2nd examiner (FA) was 0.89. The inter-rater agreement among 1st examiner (MS) and 3rd examiner (SC) was 0.89. And the inter-rater agreement among 2nd examiner (FA) and 3rd examiner (SC) was 0.83. All the three comparisons show an almost perfect agreement between them. CONCLUSION There is an almost perfect agreement between multiple observers for classifying dental cervical abrasions using Sawai's classification. Hence, this classification is reliable.