Objective: The purpose of this study was to determine the educational impact of online classes on clinical training, by comparing and evaluating the clinical training examination scores between 2019 and 2020. As a precaution against the spread of COVID-19, we reduced the number of clinical training days in our outpatient department by half. The simulation training time for the 2020 clinical training batch at our university was also reduced. Online classes were initiated to supplement the clinical training. However, the educational impact of such changes in the clinical training schedule is not clear.

Method: Fifth-year students attending the Showa University School of Dentistry (111 students of the 2019 batch and 90 students of the 2020 batch) participated in this study. The average examination scores of the students (examination conducted on simulated tartar removal with a sickle scaler) in both years were calculated and analyzed. Additionally, we analyzed the correlations between the clinical examination scores of the students after the simulation training and the order in which the students took the simulation training (we divided the students taking the online classes into two groups and those taking the simulation training into three groups, with classes for each conducted on a different day of the week, due to limitations in the number of instruments available). To confirm that this division of students into different groups did not affect the examination scores, and also determine the correlations between the clinical examination scores and the scores on the online class assignment (simulated tartar removal using a sickle scaler), we compared the clinical examination scores with the scores on the online assignment.

Results: The scores in the clinical training examination held in 2020 were lower than those in the examination held in 2019, although the difference was not significant. Dividing the students taking the online classes and simulation training into different groups did not have any statistically significant effect on either the clinical examination scores or on the scores on the online class assignments. The scores of the students in the practical examinations after the online classes and simulation training were significantly higher than the scores in the completed online class assignments.

Conclusion: The clinical examination scores of the students were lower in 2020 than in 2019 due to the reduction in the number of training days to half and the decrease in simulation training time. However, the difference was not significant. Based on the results, it is considered that online classes can be used as a supplement to clinical training.

A clinical study to investigate the relationship between The Japan Dental Association classification of periodontitis (JDA 2007), which is widely used in current dental practice in Japan, and the clinical attachment level (CAL) was conducted by 10 Japanese clinicians for 5 years, from 2016 to 2021. The study subjects included 1,375 patients with a total of 125,468 teeth. We thought that clarification of the relationship between the new classification of periodontitis (AAP・EFP 2018) and the results of this investigation would be clinically significant to calculate the periodontitis index. The JDA 2007 periodontitis classification does not include determination of the CAL. Therefore, the relationships between the periodontitis classification (JDA 2007) and the stage and grade of the new periodontitis classification (AAP・EFP 2018) were examined via the CAL value (including the PD value and degree of tooth mobility) based on the results of the above clinical study, in which the CAL value was determined for each tooth. When looking at the number of teeth tested for "CAL at the site of greatest loss" for versus "the Severity" classification in the new classification of periodontitis (AAP・EFP 2018), the correspondence of the JDA 2007 periodontitis classification (P0, P1, P2, P3, P4) to the stages (I, II, III, IV) was determined to be P0 for stage I, P1 for stage II and P2 for stage III and IV in the majority of cases. In terms of the "Maximum probing depth and tooth mobility" for "Complexity", the correspondence was P1 for stage I, P2 for stage II and III, and P3 for stage IV in the majority of cases. However, the relationship between the two classifications was not clear about "tooth loss" for "the Severity" of staging and for "Longitudinal data (CAL)" for "Direct evidence of progression" of grading. This is presumably attributable to the different scope of classification of the test items between the two groups and/or uneven distribution of the number of cases.