Flossing your teeth at least once a week may be linked to a lower risk of stroke caused by a blood clot blocking brain blood flow and irregular heartbeats, according to a preliminary study presented at the American Stroke Association’s International Stroke Conference 2025, held in Los Angeles, Feb. 5–7, 2025.

“A recent global health report revealed that oral diseases — such as untreated tooth decay and gum disease — affected 3.5 billion people in 2022, making them the most widespread health conditions,” said study lead author Souvik Sen, M.D., M. S., M.P.H, chair of the Department of Neurology, Prisma Health Richland Hospital and the University of South Carolina School of Medicine in Columbia, South Carolina.

“We aimed to determine which oral hygiene behavior — dental flossing, brushing or regular dentist visits — has the greatest impact on stroke prevention.”

The Atherosclerosis Risk in Communities (ARIC) study, one of the first large-scale investigations of this kind in the U.S., 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 which 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% lower risk of ischemic stroke, 44% lower risk of cardioembolic stroke (blood clots traveling from the heart) and 12% lower risk of AFib.
• The associated lower risk was independent of regular brushing and routine dental visits or other oral hygiene behaviors.
• 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.

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. More than 12 million people are projected to have AFib in the United States by 2030, according to the American Heart Association’s 2025 Heart Disease and Stroke Statistics.

“Oral health behaviors are linked to inflammation and artery hardening. Flossing may reduce stroke risk by lowering oral infections and inflammation and encouraging other healthy habits,” Sen said.

“Many people have expressed that dental care is costly. Flossing is a healthy habit that is easy to adopt, affordable and accessible everywhere.”

Study limitations include that data were 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 behaviors over the years, Sen said.

“This study offers more insights into the specific dental health behaviors that may be linked to stroke risks and potential risk reduction,” said Daniel T. Lackland, Dr.P.H., FAHA, American Heart Association EPI and Stroke Council member and professor of epidemiology and director of the Division of Translational Neurosciences and Population Studies in the department of neurology at the Medical University of South Carolina in Charleston.

“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.” Lackland was not involved in this study.

Study background, and details:

• The study began in 1987 and is ongoing.
• Of the 6,258 participants, 82% were self-reported white adults and 18% Black adults. Their average age was 62 years and 55% were women.
• Potential participants were excluded if they had total tooth loss, dental implants, heart disease, organ transplant, artificial joints, implanted heart valve or stent or major surgery.