Could diligent flossing and brushing lower the risk of a heart attack? It isn't as odd as it might sound.

Some researchers think the same bacteria that rot the gums might do bad things elsewhere in the body. Surveys show that people with bad teeth and gums also tend to have more heart trouble, and circumstantial evidence is accumulating that this is more than a coincidence.The latest piece of supporting data came Monday at a meeting of the American Association for the Advancement of Science. A researcher said his animal experiments suggest that some strains of the most common bacteria that build up on teeth can trigger blood clots.

"Our data suggest that bacteria may cause blood clots that can actually obstruct coronary arteries," said Dr. Mark Herzberg of the University of Minnesota.

That could lead to heart attacks, which occur when blood clots get stuck in heart arteries already clogged with cholesterol.

Others suggest that even if dental bacteria are not harmful, the body's reaction to them could be.

People with periodontal disease have a lifelong simmering infection that causes chronic inflammation of the gums. In response, their bodies release a slow, steady stream of potent germ-killing chemicals that might in themselves be harmful.

"The ramification of this inflammation can be far-reaching," said Dr. Frank Scannapieco of the State University of New York at Buffalo, who has done research in the area.

He and others say this constant, low-level infection could play a role in other common conditions, such as diabetes, lung diseases and even premature births.

About three-quarters of adults over age 35 have some degree of periodontal disease, a painless condition that often gives off few warnings except, perhaps, red gums and bleeding when brushing.

Under the surface, however, are pockets of infection that contain billions of bacteria. If this oozing mess was out where it could be seen, it would be a bone-deep sore the size of the palms of both hands.

Large-scale studies suggest that those with bad gums and teeth have about double the usual risk of dying from heart disease.

Proving that gum disease is to blame is difficult. Heart disease and periodontal disease are both especially common among the poor. Some experts wonder if bad gums are simply a sign of poverty in people with heart trouble and not a cause of their troubles.