Adding Floss or an Interdental Brush to Your Routine May Cut Stroke Risk, Large Study Finds

Most dental advice stops at "brush twice a day," but a large Korean study published in the Journal of Dentistry on July 4, 2026 suggests that stopping there may leave an important health gap.

A population-based retrospective cohort study published in the Journal of Dentistry showed that frequent toothbrushing combined with regular use of dental floss and interdental brushes was associated with a reduced risk of ischemic stroke.

The study drew on a substantial pool of participants.

Researchers used health screening data from South Korea's National Health Insurance Service and included nearly 99,000 adults aged 40 or older who had undergone both general and oral health examinations.

Participants were divided into groups based on how often they brushed and how consistently they used floss or interdental brushes, and the results showed a clear dose-response pattern: the more regularly people used these tools, the lower their ischemic stroke risk.

Those who brushed at least twice a day and almost always used floss or an interdental brush had a 23 percent lower risk of ischemic stroke compared to the group with the poorest oral hygiene habits.

Researchers believe the connection likely runs through gum inflammation. Periodontal disease is known to drive chronic systemic inflammation, and cleaning between teeth — where a toothbrush cannot easily reach — may reduce that inflammatory burden more effectively than brushing alone.

Toothbrushing on its own is limited in its ability to remove biofilm from the spaces between teeth, whereas interdental cleaning tools can reach those areas and remove plaque more effectively.

The study is observational, meaning it cannot prove that flossing directly prevents strokes — other healthy habits common among frequent flossers could also play a role. Still, the findings reinforce a straightforward message for patients:

promoting adjunctive oral hygiene practices could represent a simple, accessible, and population-based strategy for reducing ischemic stroke risk, particularly in older adults.

For anyone looking for a low-effort addition to their daily health routine, reaching for the floss appears to be a reasonable place to start.