Gum disease doesn't just look nasty and endanger your teeth. According to a growing body of evidence, it may also be bad for your heart. A new study looks at the connection between bacteria involved in gum disease and atherosclerosis.

What the researchers wanted to know: Do people who have more bacteria associated with periodontitis have thicker carotid arteries? (The carotid arteries carry blood to the head.)

What they did: The patients in the study all live in an area of Manhattan between 145th Street and 218th Street. All are 55 or older, and all of the 657 in this analysis had teeth (because it's pretty hard to collect plaque samples if there are no teeth to collect them from). Each person had a tooth examination, and researchers collected up to eight samples of plaque from below the gumline. The researchers probed the samples for the DNA of several species of bacteria that are associated with periodontal disease. They also measured each person's carotid artery walls; a thickening inner layer of the artery wall is thought to indicate early atherosclerosis.

What they found: People with more gum-disease-causing bacteria on their teeth had thickening of carotid arteries. This supports what scientists suspect—that gum disease can contribute to cardiovascular disease. This may work through inflammation; people with more gum disease bacteria also had more white blood cells circulating in their blood. (White blood cells are part of the body's response to infection.) They did not, however, have higher levels of C-reactive protein, which is another marker of inflammation.

What the study means to you: Feel the urge to floss yet?

Caveats: Since mouth bacteria and artery thickness were measured at the same time, the study doesn't prove that one caused the other, just that there's a pretty interesting relationship between the two. (But, considering the biology, it seems likely that the presence of bacteria caused the arteries to thicken.)

Find out more: An article about gum disease from the Food and Drug Administration

Read the article: Desvarieux, M. et al. "Periodontal Microbiota and Carotid Intima-Media Thickness." Circulation. Feb. 8, 2005, Vol. 111, pp. 576–582.

Abstract online: http://circ.ahajournals.org