Published: February 15, 2005

Gum disease has long been suspected of playing a role in heart disease and stroke. Now, a new study appears to make the relationship much more solid.

Writing in the journal Circulation, researchers report that people with gum disease are more likely to have changes in the carotid artery - a sign of atherosclerosis.

The researchers measured the levels of 11 bacteria from the mouths of more than 650 volunteers.

After taking into account known risk factors for vascular disease like hypertension, they looked for a link between various combinations of bacteria and thickening of the carotid artery, which they measured with ultrasound.

"The people who had the highest level of the four bacteria that were causally related to periodontal disease also had the thickest carotid arteries," said the lead author of the study, Dr. Moïse Desvarieux of the Mailman School of Public Health at Columbia.

One explanation may be that gum disease, like any other chronic infection, puts a stress on the body's immune system that can gradually lead to vascular disease, the study said.

So should people who want to avoid a heart attack reach for the dental floss? Dr. Desvarieux was cautious, noting that while an association between the bacteria and vascular disease seemed clear, the bacteria had not yet been proved to cause illnesses other than gum disease.

"Having said that," he said, "it's very hard for anybody to be against people having good oral health."