A new study has shown an independent association between periodontal disease and incident stroke risk. What’s interesting is routine dental care can attenuate the stroke risk.

“The more severe the periodontal disease, the higher the risk of future stroke is,” said primary investigator Dr Souvik Sen from the University of South Carolina School of Medicine in Columbia, South Carolina, US. However, individuals who regularly attend the dentist had half the stroke risk of those who do not receive regular dental care.”

Periodontal disease characterized by increased inflammation, for example, gingivitis and severe periodontitis had the strongest association with stroke risk. “The risk is about two to three times higher in individuals with severe [periodontal] disease,” said Sen. “The risk [brought about by gum disease] is similar to that of high blood pressure.”

The study involved 10,362 middle-aged individuals with no history of previous stroke participating in the Atherosclerosis Risk in Communities (ARIC) study.  The pattern of their dental visits was classified as regular (more than once a year) or episodic (only when needed or never). Within 15 years of follow-up, 584 individuals had an incident of ischaemic stroke. [Stroke 2018;doi: 10.1161/STROKEAHA.117.018990]

Selected individuals from the ARIC study (n=6,736) were included in the ancillary dental ARIC study and were assessed and classified into seven periodontal profile classes (PPCs), from A to G (healthy to severe periodontal disease). Of these, 299 went on to have an incident ischaemic stroke in the follow-up period.

Risk lower with regular dental care

The incidence of ischaemic stroke per 1,000 person-years was 1.29 for PPC-A (the reference healthy group without periodontal disease), 2.82 for PPC-B (mild periodontal disease), 4.80 for PPC-C (high gingival index score), 3.81 for PPC-D (tooth loss), 3.50 for PPC-E (posterior disease), 4.78 for PPC-F (severe tooth loss), and 5.03 for PPC-G (severe periodontal disease).

Periodontal disease was significantly associated with cardioembolic stroke (hazard ratio, 2.6, 95 percent confidence interval [CI], 1.2–5.6) and thrombotic stroke (HR, 2.2, 95 percent CI, 1.3–3.8), but not lacunar strokes.

Regular dental users had a lower risk of stroke (crude hazard ratio [HR], 0.52] vs episodic users. The risk remained lower for regular dental users after adjusting for age, sex, BMI, hypertension, diabetes, smoking, race/centre, low-density lipoprotein level, and other factors (adjusted HR, 0.77).

Oral and heart health: The connection

Association cannot prove causation. However, more studies have shown that the bacteria found in gum disease, for example, Streptococcus sanguinis, can attach to the bloodstream and damage the heart valves, resulting in endocarditis.

“Our findings support the link between gum disease and stroke. The mechanism is to do with atherosclerosis and/or atrial fibrillation,” said Sen.  “Of note, good dental hygiene can mitigate the risk. The message is that good regular dental care, including a thorough home cleaning routine with brushing and flossing and regular dentist visits, can do more for heart health.”