Regular Flossing Tied to Reduced Ischemic Stroke Risk

Regular dental flossing is linked to a lower risk for ischemic stroke, primarily by reducing systemic inflammation, which can lead to atrial fibrillation (AF) increasing the likelihood of a cardioembolic event, new research suggested.

The reduced risk is independent of oral care such as regular teeth brushing and visits to the dentist, the research showed.

“We knew that flossing regularly will lower the body’s level of inflammation, and the level of oral infection, but now, based on this study, we know it will reduce the rate of stroke, atrial fibrillation, and cardioembolic stroke,” study investigator Souvik Sen, MD, professor and chair, Department of Neurology, University of South Carolina School of Medicine Columbia, told Medscape Medical News.

Flossing is an affordable health measure that could be “a very good primary prevention strategy,” especially in rural areas where individuals have less access to dental care, said Sen.

The findings were presented on February 5 at the International Stroke Conference (ISC) 2025.

Unclear Link 

Recent research has shown flossing lowers the risk for myocardial infarction. When it comes to stroke and AF, previous studies showed an association with oral infection, but the impact of preventative oral care such as dental flossing was unclear.

The study included 6278 participants in the Atherosclerosis Risk in Communities (ARIC) study with no history of stroke or AF (mean age, 62 years). The ongoing ARIC study began in 1987 in four US counties.

On visit four (1996-98), participants completed a structured questionnaire on oral hygiene. Respondents were asked if, and how often, they flossed. At least once a week was considered regular flossing. They were also asked how often they visited a dentist. Once a year was considered regular dental care. Participants also reported vascular risk factors and socio-demographic features.

Participants were categorized as flossers (n = 4092) and nonflossers (n = 2186).There were more women in the flosser group than in the nonflosser group and more men in the nonflosser group than in the flosser group. In addition, the percentage of African Americans was almost twice as high in the nonflossing group than in the flossing group.

Flossers had fewer relevant cardiovascular risk factors. For example, 31.5% of flossers had hypertension and 11.7% had diabetes vs 36.3% and 16.1%, respectively, of the non-flossers.

Flossers also had significantly higher high-density lipoprotein levels and significantly lower levels of periodontal disease and dental caries.

‘A Big Finding’

Participants had regular follow-up for > 25 years. If a stroke was reported, this was followed up through medical records. An independent neurologist verified the stroke and determined the type, said Sen.

During the follow-up period, 434 strokes were identified. Of these 146 were thrombotic, 102 cardioembolic, and 95 lacunar subtypes.

Researchers controlled for a number of factors including age, gender, race, obesity, blood pressure, diabetes, education level, smoking, regular brushing, and regular visits to the dentist.

The investigators found that flossing was significantly associated with a lower risk for ischemic stroke (adjusted hazard ratio [HR], 0.79; 95% CI, 0.64-0.97), cardioembolic stroke subtype (adjusted HR, 0.56; 95 CI, 0.36-0.86) and AF (adjusted HR, 0.88; 95% CI, 0.78-1.00).

The analysis suggested the stroke risk reduction was “primarily driven” by fewer cardioembolic strokes, “which is possibly linked to a reduced rate of atrial fibrillation,” said Sen.

“That’s a big finding because atrial fibrillation seems to be increasing and more and more people are having a stroke from atrial fibrillation. I think we haven’t focused enough on how to prevent atrial fibrillation in the first place because that leads to bigger and more devastating strokes,” Sen added.

Additional Benefit With Flossing

He noted that the results are independent of tooth brushing and regular visits to the dentist. “The results are above and beyond taking care of your oral health and suggest that flossing has an additional impact.” 

Flossing removes food particles or plaque stuck between teeth and cleans the gums, and does this better than brushing can, explained Sen. Plaque can cause gum disease and tooth decay, which can lead to inflammation, he added.

“Inflammation has been tied to hardening of the blood vessels, or atherosclerosis, and that leads to heart attack and based on our study, to stroke and irregular heartbeat.” 

Flossing was not significantly associated with thrombotic stroke (adjusted HR, 0.91; 95% CI, 0.63-1.32) or lacunar stroke (adjusted HR, 1.14; 95% CI, 0.54-1.88). There was a significant dose-effect between the frequency of flossing and the reduction in incident ischemic stroke, noted Sen.

Commenting on the research on behalf of the American Heart Association/American Stroke Association, Daniel T. Lackland, DrPH, FAHA, professor of epidemiology and director, Division of Translational Neurosciences and Population Studies, Department of Neurology, Medical University of South Carolina, Charleston, South Carolina, said the study addresses whether “there’s some part of dental hygiene” that could reduce the risk for stroke.

The study added new information that suggests “perhaps dental flossing is associated with a lower risk of cardiovascular disease,” said Lackland, who is also an American Heart Association Epidemiology and Stroke Council member.

The ARIC study is funded by the National Institutes of Health. Sen and Lackland reported no relevant disclosures.