Flossing your teeth at least once a week may be linked to a lower risk of stroke, according to a preliminary study.

Souvik Sen, study lead and chair of the Department of Neurology at Prisma Health, Richland Hospital, said, “A recent global health report revealed that oral diseases — such as untreated tooth decay and gum disease — affected 3.5bn people in 2022, making them the most widespread health conditions. We aimed to determine which oral hygiene behaviour — dental flossing, brushing or regular dentist visits — has the greatest impact on stroke prevention.”

The study is set to be presented at the American Stroke Association’s International Stroke Conference 2025.

Flossing as a form of prevention

The Atherosclerosis Risk in Communities (ARIC) study assessed the home use of dental floss through a structured questionnaire of more than 6,000 people. Among those who reported flossing, 4,092 had not experienced a stroke, and 4,050 had not been diagnosed with an irregular heartbeat known as atrial fibrillation (AFib).

Participants were asked about their status regarding high blood pressure, diabetes, high cholesterol, smoking, body mass index, education, regular brushing and dentist visits. During the 25 years of follow-up, 434 participants were identified as having strokes. Of those, 147 were larger artery brain clots, 97 were heart-driven clots, and 95 were hardening of the smaller arteries. Additionally, 1,291 participants were noted to have experienced AFib.

The analysis found:

  • Flossing was associated with a 22 per cent lower risk of ischemic stroke, a 44 per cent lower risk of cardioembolic stroke (blood clots travelling from the heart) and a 12 per cent lower risk of AFib.
  • The associated lower risk was independent of regular brushing, routine dental visits, or other oral hygiene behaviours.
  • Increasing the frequency of flossing had a greater chance of stroke risk reduction.
  • Flossing was also associated with a lower chance of cavities and periodontal disease.

Daniel Lackland, Stroke Council member and a professor of epidemiology, said, “This study offers more insights into the specific dental health behaviours that may be linked to stroke risks and potential risk reduction. With further research, dental health practices could possibly be incorporated into the ‘Life's Essential 8’ risk factors, which include diet, physical activity, nicotine exposure, sleep, body mass index, blood pressure, blood glucose and blood lipids.”

Researchers were surprised by the reduction of irregular heartbeats, or AFib. AFib is the most common form of irregular heartbeat. It can lead to stroke, heart failure or other cardiovascular complications.

Souik said, “Oral health behaviours are linked to inflammation and artery hardening. Flossing may reduce stroke risk by lowering oral infections and inflammation and encouraging other healthy habits. Many people have expressed that dental care is costly. Flossing is a healthy habit that is easy to adopt, affordable and accessible everywhere.”

The researchers said the study limitations include that the data was based on answers to a questionnaire, and the 25-year follow-up appears to have focused on stroke and heart outcomes only. There was no follow-up concerning flossing or other oral behaviours over the years.

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