A new study led by a University of California, Berkeley researcher suggests that women who get regular dental care reduce their risk of heart attacks, stroke, and other cardiovascular problems by at least one-third (Health Economics, September 29, 2010).
The analysis, which used data from nearly 7,000 people ages 44 to 88 enrolled in the University of Michigan Health and Retirement Study (HRS), did not find a similar benefit for men.
The study data were collected every two years from 1996 to 2004. The same individuals were followed over time, and each biennial survey included questions on whether subjects had visited the dentist and whether they had experienced a heart attack, stroke, angina, or congestive heart failure during the prior two years. Deaths from heart attacks or strokes were also included in the analysis. The study took into account other risk factors, such as alcohol and tobacco use, high blood pressure, and body mass index.
"Many studies have found associations between dental care and cardiovascular disease, but our study is the first to show that general dental care leads to fewer heart attacks, strokes, and other adverse cardiovascular outcomes in a causal way," said lead author Timothy Brown, Ph.D., assistant adjunct professor of health policy and management at University of California, Berkeley's School of Public Health.
He and his colleagues used a research method known as instrumental variables to rule out other potential factors that could account for different outcomes between groups. The use of instrumental variables is common among economists to evaluate the effects of economic policies, but it is less well-known in the clinical setting. They said this method helped them rule out self-selection bias or the possibility that people who seek dental care are different -- perhaps healthier in general -- than those who don't.
"While relatively short randomized controlled trials of specific types of dental treatment are possible, we can't run long-term randomized controlled trials of whether general dental care reduces cardiovascular disease events like heart attacks and strokes," said Dr. Brown, a health economist. "Individuals randomized to the treatment group would enjoy general dental care and those randomized to the control group would get no dental care at all. Many, if not most, people in the control group would simply get dental care on their own, destroying the experimental design, and making the results of the experiment worthless. The method of instrumental variables allows us to avoid this problem."
The fact that men and women did not benefit equally from dental care did not completely surprise the researchers. "To my knowledge, previous studies in this area have found that the relationship between poor oral health and cardiovascular disease markers varies by gender, but none have examined differences between men and women with regard to actual cardiovascular disease events," said Dr. Brown, who is also associate director of research at University of California, Berkeley's Nicholas C. Petris Center on Health Care Markets and Consumer Welfare.
"We think the findings reflect differences in how men and women develop cardiovascular disease," said study co-author Stephen Brown, M.D., a first-year ob/gyn resident at the West Virginia University Charleston Division School of Medicine. "Other studies suggest that estrogen has a protective effect against heart disease because it helps prevent the development of atherosclerosis. It's not until women hit menopause around age 50 to 55 that they start catching up with men."
The study authors suggested that for dental care to have a protective effect, it should occur early in the development of cardiovascular disease.
The researchers did not have data on the type of procedures used during the dental visit, but they pointed to other studies that indicated three-fourths of older adult dental visits involved preventive services, such as cleaning, fluoride, and sealant treatments.
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