Scientists at the University of North Carolina at Chapel Hill have found strong new evidence that gum disease, also called periodontal disease, affects the entire body and appears to contribute to dangerous hardening of the arteries.
"This study gives credibility to the common-sense belief that good dental health in necessary for good general health," said Dr. Gary D. Slade, formerly of UNC and now professor of oral epidemiology at the University of Adelaide in Australia. "We found that people with severe gum disease had high levels of C-reactive protein in their blood."
Physicians already know that levels of C-reactive protein, which is produced by the liver and found in the bloodstream, increase in response to inflammation caused by bodily infections, burns and other illnesses, Slade said.
"As dentists, we see a lot of bleeding and inflammation of the gums in people with severe periodontal disease," he said. "These results suggest that the inflammation from severe periodontal disease may spread beyond the mouth to affect general health."
"What is particularly interesting to us is that it looks like the effect of periodontal disease is about the same as being severely obese and that there appears to be a link between these two risk factors for atherosclerosis," said Dr. Steven Offenbacher, professor at the UNC School of Dentistry's Dental Research Center.
A report on the discovery appears in the May 26 issue of the Archives of Internal Medicine, a medical journal. Slade is lead author, and co-authors are Offenbacher; Dr. James D. Beck, Kenan professor of dental ecology; Dr. Gerardo Heiss, professor of epidemiology at the UNC School of Public Health; and Drs. Elisa M. Ghezzi and Estelle Riche, research assistant professors in dentistry.
The new study relied on data generated by the UNC-based Atherosclerosis Risk in Communities Study, a national, long-term, population-based investigation of hardening of the arteries with extensive data on subjects' health and risk factors for cardiovascular disease. The 5,552 subjects, who were given oral examinations along with other health tests between 1996 and 1999, lived in Washington County, Md.; Forsyth Co., N.C.; Jackson, Miss.; and several Minneapolis suburbs. When originally examined, they ranged in age from 52 to 74.
Researchers found both gum disease and body mass index -- a measure of how heavy a person is for how tall he or she is -- were linked to increases in C-reactive protein (CRP), Offenbacher said. CRP is widely believed to be a marker for inflammatory processes leading to atherosclerosis and as well as a cause of them. The protein appears to promote damage to the walls of major blood vessels in the heart, brain, legs and other areas, including formation of fatty plaques that can break away and block blood flow to major organs resulting in heart attack or stroke.
"Average measured CRP levels were about a third higher in people with extensive pockets of disease in their gums than in those with minimal disease even after controlling for age, sex, cigarette use, diabetes and other factors," Offenbacher said. "Among people with normal body mass indexes, our model showed a two-fold difference in average CRP between those who had periodontal disease and those who did not, but the difference decreased with increasing body mass index and was negligible among people who were severely obese."
The model also showed that when a person had periodontal disease, CRP levels remained elevated regardless of body mass.
That latter finding suggests periodontal disease and being overweight are associated together in some way with increased CRP levels in otherwise healthy middle-aged adults, Offenbacher said. It also suggests the need for both medical and dental diagnoses when evaluating systemic inflammation in patients.
Obese individuals with elevated CRP who have gum disease likely would benefit from losing weight and having gum disease treated aggressively, he said.
"Since atherosclerosis begins between the ages of 10 and 12, this work is further evidence also that people need to practice good oral hygiene, including flossing their teeth daily, and to avoid obesity by eating a healthy diet and exercising regularly," Offenbacher said.
Earlier research has shown that C-reactive protein levels can help predict who will suffer heart attacks and strokes and indicated that treating periodontal disease can lower CRP levels somewhat, Beck said.
"The American Heart Association now recommends that physicians test patients' CRP levels routinely when assessing their risk for heart attacks," he said. "We're still gathering longitudinal data to see whether people with periodontal disease are at greater risk of having a heart attack than people without gum problems. That may be true, but the answer is not clear yet."