Diagnostic distribution shifts among new pediatric patients in a tertiary oral medicine clinic across COVID-19-related periods: a retrospective analysis

The COVID-19 pandemic altered healthcare access and healthcare-seeking behavior. However, whether the diagnostic distribution among children attending an oral mucosal disease clinic changed across pandemic-related periods remains unclear. In this retrospective study, we used 2016–2023 data from the Department of Oral Medicine, School of Stomatology, The Fourth Military Medical University. We identified all patients aged 0–18 years who made their first eligible visit, to compare the distribution of primary oral mucosal diagnoses across the pre-pandemic (T0), pandemic-control (T1), and post-control periods (T2). To assess whether period-related differences varied by age group and whether the findings were robust to the choice of pre-pandemic reference period, we conducted an interaction analysis by age group and a sensitivity analysis. A total of 6203 eligible pediatric patients were included, with 2614 in T0, 2811 in T1, and 778 in T2. The most common diagnostic categories were recurrent aphthous ulceration (RAU), cheilitis, herpes simplex virus (HSV) infection, traumatic ulcers, geographic tongue, oral candidiasis, and mucocele. Mucocele showed the most marked increase, rising from 2.1% in T0 to 14.2% in T1 and 17.2% in T2. In contrast, HSV infection decreased from 9.4% to 4.0% and 3.5%. After adjustment for age and sex, the odds of mucocele versus all other diagnoses were higher in T1 and T2 than in T0, whereas the corresponding odds of HSV infection was lower in T1 and T2 than in T0. No statistically significant period-related differences were observed for traumatic ulcers. Geographic tongue generally showed lower proportions and lower adjusted odds, although the statistical significance of some descriptive comparisons differed slightly between the primary and sensitivity analyses. RAU showed modestly higher odds in T1 than in T0. Cheilitis showed a slight decrease from T0 to T1 and T2. Significant period-by-age-group interactions were observed for RAU and HSV infection, with the most pronounced changes among younger children. No statistically significant period-by-sex interactions were identified. Sensitivity analyses using an extended pre-pandemic baseline generally supported the main findings. The diagnostic distribution among pediatric patients varied across COVID-19-related periods. COVID-19 pandemic may have a certain impact on the onset of mucosal diseases in children. This study provides reference information on the oral mucosal disease in children during major public health disruption.