Changes in the Frequency of Dental Clinic Visits, Expenses, and Treatment Type during the COVID-19 Pandemic in Japan

Few studies have reported nationwide changes in dental visit patterns during the COVID-19 pandemic. This study aimed to clarify the impact of the COVID-19 pandemic on the type of dental treatment in Japan based on trends in the frequency of dental clinic visits per month and dental expenses per month or day. An interrupted time-series analysis was performed to examine changes in data from the national database before and after the first declaration of a state of emergency. Between March and April 2020, the monthly dental expenses per patient (MDEPP) increased by approximately JPY 950 (JPY) (p < 0.001) in patients aged <= 64 years and >= 65 years. Dental expenses per treatment (DEPT) increased by approximately JPY 300-400 (p < 0.001) in both age groups. After April 2020, the slope of the regression line for DEPT significantly increased in those aged <= 64 years (p < 0.001) and in those >= 65 years (p = 0.024). The number of treatments per month (NTPM) increased after the declaration of a state of emergency. However, the decreasing trend in the regression line for NTPM was stronger in those aged <= 64 years (p < 0.001). The MDEPP, DEPT, and NTPM showed an increasing trend during the first state of emergency compared to those observed in the previous year. The proportion of patients with relatively severe disease may have increased because patients with mild disease refrained from undergoing dental examinations. These results suggest changes in the type of dental treatment during the COVID-19 pandemic.