Poor Oral Health a Risk Factor for Stroke, UB Study Finds

BALTIMORE -- The first national population-based cohort study of periodontal disease and cerebrovascular disease, conducted by University at Buffalo researchers, has shown that people with severe gum disease are twice as likely to have the type of stroke caused by blocked arteries than those with good oral health.

The relationship of gum disease and stroke was even stronger than the link between gum disease and heart disease, said lead author Tiejian Wu, M.D., Ph.D., research assistant professor in the Department of Social and Preventive Medicine in the UB School of Medicine and Biomedical Sciences.

Wu will present results of the study here today (June 12) at the annual meeting of the Society for Epidemiologic Research.

"This is the first major study to look at this question," said Wu. "There have been a few other very limited studies, but the number of subjects was small and was drawn from restricted populations. This study also looked at subgroups -- men, women, blacks and non-blacks. Periodontal disease was associated with an increased risk for cerebrovascular disease in all groups."

Maurizio Trevisan, M.D., professor and chair of the UB Department of Social and Preventive Medicine and the study's co-author, said of the findings: "While more studies are needed for a conclusive statement about the cause-and-effect association, the consistency of the findings in different gender and racial groups, and the strength of the association between two chronic conditions prevalent in the adult population may have important implications for individual and public health."

The study cohort was comprised of 9,962 adults between the ages of 25-75 who took part in the first National Health and Nutrition Examination Survey (NHANES I) conducted from 1972-74 and its follow-up, which was completed in 1992.

Respondents' oral health was categorized as no periodontal disease, gingivitis, periodontitis or toothless, based on information collected during NHANES I. Gingivitis, an inflammation of the gums, is a relatively mild form of periodontal disease. Periodontitis, an infection of the gums, membranes at the base of the teeth and the supporting bone, is a severe form and is the major cause of tooth loss in adults.

Cerebrovascular-disease events were confirmed in the follow-up survey through hospital records and death certificates. Researchers assessed the risk for cerebrovascular event as a whole and for certain specific events: non-hemorrhagic stroke, hemorrhagic stroke and transient ischemic attack, or TIA.

Results showed that periodontitis was a significant and independent risk factor for developing cerebrovascular events and for non-hemorrhagic stroke -- loss of blood flow to the brain due to a blockage rather than a burst vessel.

Periodontitis was associated with a two-fold increase in non-hemorrhagic stroke risk. The study found no association between periodontal disease and hemorrhagic stroke or TIA.

Wu said periodontal disease is thought to increase the risk of stroke in much the same way it increases the risk of heart attack. "Bacteria, endotoxins and other bacterial products from gum pockets enter the circulation and may promote an inflammatory response, causing cells to proliferate in the blood vessels and the liver to increase production of clotting factors. Bacteria may also attack the vessel lining and damage endothelial cells.

"Further, several periodontal pathogens can induce platelet aggregation and may promote plaque formation that can cause blockages and clotting," he said.

An earlier study conducted by UB researchers found periodontal bacteria in samples of carotial arterial plaque taken at the time of surgery.

Also participating in this study were Robert J. Genco, D.D.S., Ph.D., professor and chair of the UB Department of Oral Biology; Joan P. Dorn, Ph.D., assistant professor, and Karen L. Falkner, Ph.D., research assistant professor, both of the UB Department of Social and Preventive Medicine, and Christopher Sempos, Ph.D., senior scientist at the National Institutes of Health.