Sept.19, 2000 -- Though the two may seem completely unrelated, some researchers have claimed that gum disease may lead to heart disease. But before you worry, new research is showing the link between gum disease and the risk for developing heart disease is far from a "floss or have a heart attack" situation (although it would be a heck of an ad campaign for floss manufacturers).
In fact, researchers from the University of Washington's School of Dentistry, who looked at government data that followed more than 8,000 people for about 20 years, found no strong evidence to indicate that people with gum disease are at higher risk for developing heart disease.
"I think at this moment there is a lot of good reason to floss, but people should not be concerned that gum disease may cause heart disease," study author Philippe Hujoel, PhD, tells WebMD. Hujoel, a periodontist, is an associate of professor of dental public health sciences at the University of Washington in Seattle.
The idea that gum disease may be associated with a higher risk for heart disease, and even cause heart attacks, has been supported by a few small studies, says Hujoel; but he notes that two other large studies have not found a connection. Nor has his study, which appears in the Sept. 20 issue of the Journal of the American Medical Association. "Our study finds the association is either nonexistent or it is so small that you need a very large study to find out," Hujoel says.
There are several theories as to how gum disease could cause heart disease. The first is that the organisms that cause gum disease leave the mouth area and travel to infect the heart. A second is that the microorganisms in the mouth, once they get out and circulate in the blood, contribute to the build-up of fatty deposits in the heart. A final possibility -- one that experts say currently is the most plausible -- is that the heart is weakened by agents in the blood that respond to inflammation -- and in the case of chronic gum disease, there is constant inflammation.
Hujoel and his colleagues looked at data from a large government study that tracked more than 8000 subjects, aged 25 to 74 years old, between 1982 and 1992. At the start of the study in 1971 to 1975, none of the subjects had a history of heart disease, although more than half of them had some type of gum disease, either periodontitis or gingivitis (both of which involve inflammation of the gums).
The researchers noted that the participants with gum disease tended to be male, less educated, black, and poorer than the study participants with healthy gums. They also were older and were more likely to have other heart disease risk factors, including diabetes, high blood pressure and high cholesterol levels, being overweight and smoking.
In fact, Hujoel comments, "The biggest challenge in studying this kind of association is that the risk factors for gum disease are very similar to the risk factors for heart disease. For instance, a textbook example is smoking: It is probably one of the biggest risk factors for gum disease, and it is very well known that it is also a risk factor for heart disease. So given that there are so many common risk factors for both diseases, it is very difficult to completely eliminate any [confusion between the risk factors] that may be occurring."
During the follow-up, about 15% of the participants had either died of heart-related causes, been hospitalized for heart disease or had surgery to clear up blocked arteries.
Overall, the researchers found that people with gum disease were two-and-a-half times more likely than those with healthy gums to experience a medical "event" related to heart disease. But when they took into account the other heart disease risk factors (such as diabetes, smoking, obesity, etc), they found that people with gum disease were not at greater risk for developing heart disease.
"Some people strongly believe there is a link [between gum disease and heart disease], but the evidence is pretty strong that we are looking at a small association," says Hujoel, pointing out that his study did find a small but insignificant link.
"It is very difficult in my opinion to draw a causal association," Andy Teng, DDS, PhD, tells WebMD. Teng, a periodontist and an oral pathologist at the University of Western Ontario, was not involved in the study.
But Teng says that just because there isn't a causal connection, doesn't mean there isn't some other kind of association. "[Gum] disease could be an important modifier of heart disease. ... I personally believe we are looking at something that would modify the [heart] disease progress, either slow it down or exacerbate the progression."
Other experts agree. Jeffrey Ebersole, PhD, is the director of the Center for Oral Health Research at the University of Kentucky in Lexington. He tells WebMD, "This infection, in and of itself, is not enough to trip the balance, but if you superimpose upon that a number of other cardiovascular risks within a patient, that might be something that will push them off a cliff, relative to an event."
Mitchell Elkind, MD, tells WebMD, "Because [gum] disease is so prevalent and so common ... we might need a much larger study to find an association. But if there is even a small association then, extrapolated over the number of people with [gum] disease in the U.S., that could be significant way to intervene and help people." Elkind is an assistant professor of neurology at Columbia University's College of Physicians and Surgeons.
"I think we all accept that there are many different risk factors and causes for heart disease, and the more risk factors you have the more likely you are to end up with a [problem]," Elkind says. "Heart disease is such a prevalent disease, such an important process, that you wouldn't want to miss even one small contributor and that it why it is worth not throwing the baby out with the bathwater."