Floss this morning?
Anybody who's ever been to a dentist has heard it already: Flossing and brushing keep the gums healthy so your teeth don't fall out, etc., etc., etc. But don't stop reading. This story won't bore you with the standard lecture about why flossing is good.
No, the news here is something the hygienist probably didn't say. It turns out more could be at stake than teeth. Maybe your heart, for instance.
Scientists are investigating the idea - odd as it sounds - that bad gums create mischief in places far from the mouth. Indeed, they say the bacteria that live around the teeth, or perhaps the body's reaction to them, may even contribute to the diseases that eventually do you in.
At a recent conference on the subject at the University of North Carolina, Raul Garcia playfully flashed a slide that summed up what many in the audience were probably starting to think:
"Gum disease kills," it warned. "Floss or die."
Dr. Garcia, a dentist at the Veterans Administration Outpatient Clinic in Boston, is the first to admit that none of this has been proven. No one can say with certainty that bad gums do anything worse than ruin your teeth. But a strong circumstantial case has started to form.
"It's not an unreasonable hypothesis, although on the surface it appears to be a leap of faith," says Dr. Steven Offenbacher, a dental researcher at the University of North Carolina.
Dr. Offenbacher is studying the possibility that gum disease is a major trigger of premature births. Others are examining the theory that it helps clog the arteries and cause heart attacks. Still others wonder if it contributes to diabetes.
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, literally, billions of bacteria. If this oozing mess were out where it could be seen, it would be a bone-deep sore the size of the palms of both hands.
In theory, this load of bacteria creates a smoldering, low-grade infection that inflicts its damage slowly over time. The main evidence so far comes from studies that follow large numbers of people to see if those who have bad gums fare differently from those who don't. The studies strongly hint that people with periodontal disease have a higher than usual risk of heart attacks.
Among the most impressive is the VA's Normative Aging Study in Boston, which has followed 1,231 men who were outwardly healthy when they were given thorough dental exams in the 1960s. The men who started out with bad gums have had about twice the death rate in the years since, especially from heart disease.
Another study, conducted on 44,119 male health professionals at the Harvard School of Public Health, also found poor health among men who were missing many teeth, a sign of gum disease. During six years of follow-up, those with 10 or fewer teeth had about a two-thirds higher risk of heart disease than men with close to a full set of teeth.
Yet another study from the Marshfield Medical Research Foundation in Wisconsin checked on the health of 9,760 Americans surveyed in the early 1970s. By 1987, heart disease was 25 percent more common in those who had gum disease at the outset. But the risk was especially great for men under age 50 at the start. They had about a 75 percent greater risk of heart trouble.
These studies suggest that bad gums could be as strong a risk factor for heart attacks as smoking cigarettes, which is blamed for about 40,000 heart-related deaths a year.
The statistical link with premature births is less convincing, but it is one researchers are pursuing avidly because of its clues for dealing with an especially knotty public health problem. About 250,000 infants are born prematurely and dangerously small in the United States each year; prematurity is by far the leading cause of newborn deaths.
Doctors have long noticed that women with bad teeth seem more likely to give birth prematurely. Dr. Offenbacher studied 124 women and found those with gum disease were about eight times more likely than usual to deliver dangerously small premature babies.
Extrapolating such a small study to the entire country is risky. But it raises the possibility that bad gums might be responsible for 18 percent of all low-weight premature births.
Doctors are intrigued by the idea that something as simple as treating bad gums might lower this risk.
"It's not very clear most of the time what causes premature births. If you have something you can fix, that's of tremendous importance," says Dr. Robert Goldenberg, an obstetrician at the University of Alabama who is studying the link between bad gums and premature deliveries in 5,000 poor women in the rural South.
Of course, no one has proven that attending to people's teeth will have any effect whatsoever. Still, Dr. Harold Slavkin, head of the National Institute of Dental Research, seems convinced that this research is going someplace important.
"I bet this will pan out," he says. "The mechanism is not understood, but there may be a solution before we know how it works."
Indeed, how it works is a mystery. But there are three main theories:
"Like everything else, it's probably a combination of these," says Dr. Robert Genco, a dental researcher at the State University of New York at Buffalo.
The theory that gum disease - or at least some infection - promotes heart disease got a boost recently from research at Brigham and Women's Hospital in Boston. It showed that men with blood evidence of chronic infections have triple the risk of heart disease.
The study, though, could not trace the source of the infection, and there are other possible culprits, such as Chlamydia pneumonia or H. pylori, the ulcer bug.
"As cardiologists, we don't talk much about gum disease, but maybe we are the ones who are wrong," says Dr. Paul Ridker, who directed that study.
Proving that gum disease really is to blame will be difficult. For one thing, heart disease, prematurity and periodontal disease are especially common among the poor. Perhaps bad gums are simply a sign of poverty in people with heart trouble and under-sized babies, and not a cause of their troubles.
Another complication is cigarettes, which also contribute to heart attacks, low birth weight and gum disease. Smoking might help explain why they are found together.
Nevertheless, dentists say that if this unlikely hazard of gum disease turns out to be real, they know how they will use the information when it comes time for lectures.
"It would be a highly motivating spiel to give my patients," Dr. Garcia says, "about why they should floss their teeth."