Association between dental checkup frequency and longitudinal changes in total healthcare expenditures: a longitudinal cohort study

Oral health is increasingly recognized as an important component of overall health and may be associated with healthcare utilization and expenditures. However, evidence remains limited regarding the long-term association between the frequency of community-based dental checkup attendance and healthcare expenditure trajectories. This retrospective cohort study included 8,528 individuals aged 30–89 years from a Japanese municipal National Health Insurance database. Participants were classified into four groups according to the cumulative number of municipal dental checkups attended between 2013 and 2023 (0, 1–2, 3–5, and ≥6 visits). Using mixed-effects models, we examined temporal changes in log-transformed total healthcare, medical, and dental expenditures from 2015 to 2023. Sensitivity analyses using individual fixed-effects models and an alternative exposure definition based on baseline-period (2013–2014) dental checkup attendance were conducted to assess the robustness of the findings. Age-stratified analyses were conducted to assess whether the associations differed across age groups. Compared with the 0-visit group, participants with ≥6 dental checkups showed a significantly more pronounced decrease in total healthcare expenditures over time (interaction β = −0.507, p < 0.001). By contrast, dental expenditures were initially higher among attendees, but the between-group differences narrowed over time. The findings were consistent in both sensitivity analyses. The association between dental checkup attendance and expenditure trajectories varied by age, with more pronounced associations observed among participants aged 50–79 years. Dental checkup attendance was associated with more pronounced decreases over time in total healthcare expenditures. However, these findings should be interpreted as associations between long-term dental checkup attendance patterns and expenditure trajectories rather than as causal effects.