A study tracked 5,986 adults, with an average age of 63, for two decades.

People with cavities and gum disease may face a higher risk of ischemic stroke, according to a study published in the journal Neurology.

Ischemic strokes are the most common type of stroke and occur when a clot or blockage reduces blood flow to the brain, depriving it of oxygen and nutrients.

“We found that people with both cavities and gum disease had almost twice the risk of stroke when compared to people with good oral health, even after controlling for cardiovascular risk factors,” said Souvik Sen, of the University of South Carolina in Columbia and the study’s lead author. “These findings suggest that improving oral health may be an important part of stroke prevention efforts.”

Researchers analysed data from 5,986 adults with an average age of 63 who had no prior history of stroke at the start of the study. All participants completed dental exams that assessed whether they had gum disease, cavities or both. They were then placed in three groups: having a healthy mouth, gum disease only or gum disease with cavities.

The participants were tracked by the researchers for two decades, using phone visits and medical records to determine which people had a stroke. Of 1,640 people with healthy mouths, 4% had a stroke, of 3,151 people with gum disease only, 7% had a stroke and of 1,195 people with gum disease and cavities, 10% had a stroke.

After adjusting for factors such as age, body mass index and smoking status, researchers found when compared to people with healthy mouths, those with both gum disease and cavities had an 86% higher risk of stroke. Those with gum disease alone had a 44% increased risk.

The study also found that people with both gum disease and cavities had a 36% higher risk of experiencing a major cardiovascular event, such as a heart attack, fatal heart disease or stroke when compared to people with healthy mouths. Participants who reported visiting the dentist regularly had an 81% lower chance of having both gum disease and cavities and 29% lower odds of having gum disease alone.

A limitation of the study is that participants’ oral health was assessed only once, at the start of the study, so changes in dental health over time were not captured. It is also possible that other unmeasured health factors contributed to the findings. The researchers said the study does not prove that poor oral health causes strokes; it only shows an association.