This month, a team of researchers from London and the University of Connecticut announced that aggressive treatment of gum disease can improve the function of blood vessel walls in the body -- potentially reducing the risk of heart attacks.
A few weeks before that, researchers from the Harvard School of Public Health reported a study of more than 51,000 male health professionals, which showed that men who had gum disease, or periodontitis, were far more likely than those without it to develop pancreatic cancer.
The evidence is accumulating faster than you can say "don't forget to floss" that taking good care of your teeth -- and treating gum disease aggressively -- may be one of the best things you can do not just for your mouth, but for your overall health.
With pancreatic cancer, for instance, previous studies had suggested such a link, but those studies were muddied because many participants smoked -- and smoking is a risk factor for both diseases.
This time, even among people who had never smoked, gum disease was linked to a doubling of the cancer risk, said epidemiologist Dominique Michaud, the first author, of the Harvard School of Public Health. It's still not clear, cautioned Michaud, whether that means the gum disease led to the cancer.
Chronic inflammation anywhere -- including swollen gums -- makes the body release nasty chemicals called cytokines that have been linked to many problems, including diabetes and heart disease.
The crucial point is that "oral infections have systemic effects," said Dr. Thomas Van Dyke, a professor of periodontology and oral biology at the Boston University School of Dental Medicine.
In some cases, these systemic effects are probably linked to the direct spread of oral bacteria through the bloodstream to other parts of the body.
In other cases, oral bacteria have been found in plaques in artery walls, although it is not clear whether these bacteria are a cause of heart disease or are merely incidental, said Dr. Bruce Pihlstrom, acting director of the center for clinical research at the National Institute of Dental and Craniofacial Research, part of the National Institutes of Health.
But most of the systemic problems linked to periodontitis, which affects millions of Americans, are believed to be problems of chronic inflammation.
The clearest example is the association between periodontitis and diabetes, said Dr. Robert J. Genco, a periodontologist at the University of Buffalo.
He and others have shown that diabetics have more severe periodontal disease and have it at an earlier age than nondiabetics. And it's a two-way street: People with diabetes with periodontitis have more trouble controlling blood sugar than diabetics without periodontitis.
It makes sense. Cytokines, such as those generated in chronic gum inflammation, can disrupt the system by which insulin, the hormone that escorts sugar into cells, sends chemical signals inside cells. This can trigger insulin resistance, which often leads to diabetes.
And obesity -- long known as a major cause of diabetes, in part because fat cells in the abdomen pump out so many cytokines -- is also now seen as a direct risk factor for periodontitis, said Genco.
(Like Van Dyke, Genco is a co-author of a Scientific American publication on oral health paid for by Proctor & Gamble, makers of Crest toothpaste and Oral-B electric toothbrushes. It is available online at dentalcare.com/soap/products/index_promotion_ sa.htm.)
Cytokines can also trigger inflammation in artery walls, raise blood pressure, worsen cholesterol profiles and increase the tendency for blood to clot, which can lead to potentially fatal heart attacks.
Animal studies have also shown that deliberately inducing periodontitis triggers plaque buildup in the coronary arteries, said epidemiologist Kaumudi J. Joshipura, director of the division of dental public health at the University of Puerto Rico in San Juan.
A large study published in 2003 in the online journal Stroke showed that people who had lost a lot of teeth were more likely to have severe periodontal disease and clogged coronary arteries.
Another study that year showed a direct link between periodontal disease and stroke in people who had never smoked. And a study published in 2005 in the journal Circulation showed that older adults with higher levels of periodontitis-causing bacteria in their mouths also had thicker neck arteries supplying the brain, a predictor of heart attack and stroke.
Pregnancy complications, too, have been linked to gum disease, perhaps because chronic inflammation leads to high levels of a hormone-like substance called prostaglandin E-2, which can induce labor.
But last year, a study in the New England Journal of Medicine of 823 women with periodontal disease showed that treatment did not lower the risk of premature or low birth-weight babies. A second government study of 1,800 more women is under way.
"The associations between periodontitis and systemic disease are provocative and important," said Pihlstrom of the national dental institute.
But even if there were no links to systemic health, "Taking care of your mouth is important for its own sake," Pihlstrom said. Regular brushing, flossing and visits to a dentist can help reduce the risk of periodontitis -- and can help you keep your teeth as you get older.
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