Flossing may reduce risk for stroke and irregular heart rhythm

Flossing regularly may lower the risk of some strokes as well as a type of irregular heart rhythm that can increase stroke risk, new research suggests.

The findings, which will be presented Wednesday at the American Stroke Association's International Stroke Conference in Los Angeles, show people who flossed at least once a week had a lower risk for strokes caused by blood clots coming from the heart and for an irregular heart rhythm called atrial fibrillation, or AFib, that can lead to a stroke. The findings are considered preliminary until the full results are published in a peer-reviewed journal.

"I wouldn't say dental flossing is the only thing you need to do to prevent a stroke, but our findings suggest it is one more thing to be added to a healthy lifestyle," said lead researcher Dr. Souvik Sen, a professor and chair of the neurology department at the University of South Carolina in Columbia.

Sen said prior studies have shown a link between oral health, oral infection and damage to white matter and small blood vessels in the brain, as well as to a buildup of plaque in the arteries that supply blood to the brain.

The new study included 6,278 participants who had answered questions about home use of dental floss. About 65% of the participants reported flossing at least once a week.

Participants were followed for 25 years to see if they developed AFib or had an ischemic stroke, which occurs when a blood vessel to the brain is blocked. The researchers also looked at the risk of specific types of ischemic stroke: thrombotic strokes, caused by a blood clot in large arteries in the brain; cardioembolic strokes, caused by a clot traveling to the brain from the heart; and lacunar strokes, clots that occur in small arteries deep in the brain.

Compared to non-flossers, people who flossed experienced a 22% lower risk of an ischemic stroke, a 44% lower risk of a cardioembolic stroke, and a 12% lower risk of AFib, which developed in 20% of study participants. The analysis showed no link between flossing and thrombotic or lacunar strokes.

"Dental flossing reduces oral infections and gum disease, which are linked to inflammation," Sen said. Because inflammation can contribute to the risk for stroke, "it would make sense that if people flossed regularly, it might also reduce the risk of stroke and AFib."

Dr. Karen Furie, neurologist-in-chief at Brown University Health in Providence, Rhode Island, said she wasn't surprised that flossing might help reduce stroke risk.

"Flossing does help get debris out from between teeth that brushing alone might miss," said Furie, who also is chair of neurology at the Warren Alpert Medical School of Brown University. "Things that cause inflammation to the gums might be retained food or seeds, things that if not removed might inflame the gums and contribute to a systemic inflammatory state that might affect the health of the blood vessels."

But Furie, who was not involved in the study, was surprised the investigation found no association between flossing and thrombotic strokes, because of their link to inflammation and atherosclerosis, the buildup of plaque in the arteries.

"I would have thought this type of stroke would have been the most reduced," she said. "It's possible that people who have thrombotic strokes, which you can anticipate because you can see evidence of atherosclerosis in the arteries, were being managed more vigorously than people who had cardioembolic strokes, which come out of the blue."

The lower stroke risk could stem from "something fundamentally different about people who floss," Furie said. "The 65% who floss may be people who follow the recommendations of their dentists and doctors and are attentive to the small details of health maintenance. They might be different than the 35% who don't floss, who might not be as compliant or might have other lifestyle or medical factors that reduce their compliance."

Managing blood pressure and cholesterol, maintaining a healthy weight, staying physically active, eating a healthy diet and getting enough sleep are all important steps people can take to help prevent strokes, Furie said, but the new study "shows good dental health also matters. That is an important message and something people don't appreciate. Many neglect their oral hygiene, and hopefully this calls attention to it being an important aspect of total good health."