Age‐Specific Changes in Chewing Discomfort During the Expansion of National Health Insurance Coverage for Dental Implants: A Controlled Interrupted Time Series Analysis in South Korea, 2010–2024

BACKGROUND: Chewing discomfort related to tooth loss is a common functional problem among older adults, and high out-of-pocket costs for prosthodontic rehabilitation may limit access to treatment. OBJECTIVES: To assess whether age-specific trends in self-reported chewing discomfort changed around South Korea's stepwise expansion of National Health Insurance coverage for dental implants relative to a younger comparison group. METHODS: This study used nationally representative repeated cross-sectional data from the Korea Community Health Survey (2010-2024). A controlled interrupted time series design, using adults aged 60-64 years as the comparison group, assessed age-specific trajectories before and after phased implementation (2014 for ≥ 75 years; 2015 for 70-74 years; 2016 for 65-69 years). Chewing discomfort was defined as self-reported discomfort when chewing due to problems with teeth, dentures or gums. Survey-weighted segmented logistic regression models were used to estimate immediate level changes and post-intervention slope changes. A sensitivity analysis used adults aged 55-64 years as an alternative comparison group. RESULTS: Chewing discomfort declined in all age groups, including the comparison group. No statistically significant differential immediate level change was observed. A differential post-intervention slope change was consistently observed among adults aged 70-74 years. No additional differential slope change was identified among adults aged 65-69 years, who had already shown a faster pre-intervention decline. The estimate among adults aged ≥ 75 years was no longer statistically significant when adults aged 55-64 years were used as the alternative comparison group. CONCLUSION: These findings indicate substantial secular improvement and age-specific heterogeneity in policy-timed changes in chewing discomfort, with the most consistent additional decline observed among adults aged 70-74 years. However, they do not establish an implant-specific treatment effect and highlight the need for age-sensitive, post-implementation evaluation and refinement of dental coverage based on functional outcomes.