Dentists often warn patients that inadequate toothbrushing and flossing habits could lead to gum disease and tooth loss. Now a study by Harvard University researchers suggests that losing your teeth may also heighten your risk of suffering a stroke.
The new study has found that men with fewer than 25 teeth had a 57% higher risk of suffering an ischemic stroke than those who had 25 or more teeth. Ischemic strokes are caused by blockage of an artery to the brain.
Scientists haven't yet established a direct cause-and-effect between periodontal disease and cardiovascular disease. But the latest findings add to a growing body of research linking infections, including those of the mouth, to heart disease.
Scientists have proposed several explanations. Some believe that when bacteria in the mouth get into the bloodstream, they create inflammation that increases the buildup of plaque in the arteries. Plaque can break off and lodge in the heart, causing a heart attack, or in the brain, causing a stroke. Some believe a periodontal infection makes blood more likely to clot, raising the risk of stroke or heart attack. Another idea is that the bacteria may release a toxin that damages cells lining the arteries.
Previous studies of the link between gum disease and cardiovascular disease have been mixed. One found that stroke patients were more likely to have oral infections than healthy patients, and another found that people with periodontal disease were more likely to have thickened carotid arteries in the neck.
Researchers from the Harvard School of Dental Medicine published their findings in the Dec. 13 online issue of Stroke: Journal of the American Heart Assn. The 12-year study followed 41,380 men, mostly white dentists, veterinarians, pharmacists, optometrists, osteopaths and podiatrists. All were 40 to 75 years old and had no heart disease or diabetes when they signed up.
There were 349 ischemic strokes among the men. Patients with 17 to 24 teeth had a 50% higher risk of stroke than those with 25 to 32 teeth (a full set is 32). Those with 11 to 16 teeth had a 74% higher risk; those with 10 or fewer teeth had a 66% higher risk.Stroke risk was most closely related to the number of missing teeth when a man entered the study, not the number lost in the subsequent years.
"If infection is a major factor," said Dr. Don Smith, director of the stroke program at Colorado Neurological Institute, "then good dental hygiene may achieve the level of importance in stroke prevention that we now accord to control of blood pressure, cessation of smoking, exercise and healthy diet."