Better oral hygiene is associated with lower risk of stroke

Background: Periodontal disease or poor oral hygiene may lead to local infection, inflammation, and systemic inflammatory reactions, which are important mediators of development of stroke. We aimed to investigate the association of oral hygiene with risk of stroke in a nationwide population-based cohort. Methods: From Korean National Health Insurance System-Health Screening Cohort, 206,602 participants without missing data regarding demographic information, medical history, or blood/urine examination results were included. The presence of periodontal disease and indicators of oral hygiene, such as number of tooth brushings, dental visit history, dental scaling, and number of teeth loss and dental caries were evaluated. Occurrence of stroke including cerebral infarction, cerebral hemorrhage, and subarachnoid hemorrhage was defined as newly registration of International Classification of Diseases-10 codes from I60 to I64 accompanying brain CT and/or MR examination at that time of diagnosis. Results: The 7337 (3.6%) cases of stroke including 5795 (79.0%) cases of cerebral infarction, 1568 (21.4%) cases of cerebral hemorrhage, and 621 (8.5%) cases of subarachnoid hemorrhage occurred during a median 10.4 years follow-up. In multivariable analysis, frequent tooth brushing (≥3 times per day) was negatively associated with risk of stroke occurrence (hazard ratio [HR]: 0.78, 95% confidence interval [CI]: 0.73–0.84). Number of dental caries (≥4) was positively related to stroke occurrence (HR: 1.28, 95% CI: 1.13–1.44). Conclusions: Regular oral hygiene behavior was negatively, and infrequent oral hygiene care was positively associated with risk of occurrence for stroke, respectively. Brushing one's teeth three or more times daily may be associated with lower risk of stroke.