*2.1. Study Design, Setting, and Participants*

The subjects that participated in this study were sourced from the Niigata study, a community-based cohort study investigating the relationship between oral health and systemic health in older subjects aged 70 in 2008. Sampling and data collection procedures were described in previous reports in detail [35,36]. A 20-year follow-up study was conducted in 2018 through mass examination. Dental and medical examinations were carried out. Briefly, all of our cohorts did not present with any comorbidities.
