This study aimed to investigate the frequency of dental visits after coronavirus disease 2019 (COVID-19) in children and adolescents in comparison to that of adults. The data on the number of dental visits on the basis of different classification and treatment codes for all the age groups were provided by the Health Insurance Review and Assessment Service from January 2017 to December 2020. To reduce the impact of the population change, dental visits per 1000 people was used. After the start of the pandemic, dental visits per 1000 people decreased in all age groups when analyzed for the diseases of pulp and periapical tissues classification code and dental visits per 1000 people decreased over 5 years age groups when analyzed for the pulp treatment code. Regarding the restorative treatment code, visits in the 0 - 19 years age group decreased after the pandemic. Based on the comparison of the number of confirmed COVID-19 cases to that of monthly dental visits by treatment codes, the change rate of pulp and restorative treatments gradually decreased after the waves of the pandemic in February and August 2020 in Korea. Furthermore, dental visits per 1000 people for gingivitis and periodontal disease classification code increased after the pandemic in all age groups. The rate of decrease in dental visits per 1000 people for restorative treatments in children and adolescents was higher than that in adults. The rate of decrease in the number of dental visits for multi-visit pulp treatments showed a rapid decrease as compared to that of 1-visit pulp treatments after the pandemic. This study identified changes in the number of dental visits of children and adolescents after COVID-19 transmission in comparison to that observed in adults.