Bidirectional associations between periodontal disease and systemic diseases: a nationwide population-based study in Korea.

To evaluate the associations of periodontal disease (PD) with systemic diseases, including diabetes mellitus (DM) and cardiovascular disease (CVD), as well as the reciprocal association. The CVD included the cases of coronary heart disease and heart failure. A prospective study was conducted from 2007 to 2019 using linked data from three databases in Korea. Three separate study groups were formed to individually determine the risks of PD (n = 10,533), DM (n = 14,523) and CVD (n = 14,315). All diseases were confirmed based on physicians' diagnoses using medical records and self-reports. Cox proportional hazard regression was applied with 95% confidence intervals (CIs) to obtain hazard ratios (HRs). PD was significantly associated with an elevated risk of DM (HR [95% CI]: 1.22 [1.07-1.39]) after full adjustment for age, sex, lifestyle factors, body mass index, dental behaviour and CVD. PD was also found to increase the risk of CVD (1.27 [1.03-1.57]), whereas CVD increased the risk of PD (1.20 [1.09-1.32]) after full adjustment for other covariates including DM. This study found a bidirectional association between PD and CVD, as well as a positive association of PD with DM.