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Take Good Care of Your Teeth



For most people, it's tempting to put their dental health at the bottom of the priority list: If it doesn't hurt, it's probably fine. But for a wide range of scientists and practitioners associated with UB's School of Dental Medicine, the oral cavity is a place of endless fascination-and the site of promising new investigations-in the ways oral health and whole-body health affect one another.


BY SCOTT THOMAS


    These researchers are discovering the truth of former Surgeon General C. Everett Koop's declaration, "You can't have good health without good oral health." They're studying the relationships between gum disease and such lifestyle factors as drinking and smoking; ferreting out the mechanism by which periodontal-disease bacteria may contribute to killers like heart attack and stroke; and finding new ways for dental practitioners to screen patients for problems beyond the mouth.

    It's an exciting time for dental research, both at UB and nationwide, as scientists continue to discover how pervasive the influence of oral health really is. And through publications and seminar presentations, the university continues to be a hotbed of such research.

    "Dental health in the United States is the best in the world because we're continually doing research on oral diseases," says Louis J. Goldberg, professor and dean of the School of Dental Medicine. "And our ability to diagnose and treat those diseases is directly related to research. We're able to provide an environment where students are aware of the importance of research. That we have faculty here doing this research is really to the benefit of society."

ne faculty member whose work has drawn widespread attention, among his scientific colleagues as well as in the popular media, is Robert J. Genco, SUNY Distinguished Professor and chair of the Department of Oral Biology. An affable man with a sense of humor about his work-his desk features a bumper sticker proclaiming, "FLOSS ... OR DIE!"- he's nevertheless dead serious about the health threats of oral diseases, periodontitis (gum disease) in particular. Among the half dozen types of bacteria that infect the oral tissue, Genco and his colleagues have concentrated on two particular strains in adults and one in children, studying how they act in the body and what implications they have for total-body health.

    "One of the things we've found," Genco says, "is that these organisms cause disease by triggering the host to produce tissue destruction. These bacteria induce an immune response. In people who are neutropenic (deficient in the disease-fighting white blood cells called neutrophils), gum disease can be very serious. Diabetics, for example, are known to have very poor neutrophil function, and diabetes is a risk factor for periodontal disease."

    In one study, Genco and his colleagues examined 1,500 adults in Erie County and asked, "What puts them at risk for gum disease?" The presence of gum infection, not surprisingly, was a strong factor. But they also found that cigarette smokers were five times as likely to develop gum disease, presumably because smoking reduces the protective action of the immune system. Stress, too, turned out to be a factor in gum disease. People who are under chronic financial stress-one kind of stress that's easy to measure-are at greater risk, Genco says.

    Another study found that low calcium intake is strongly related to gum disease, both for people with inadequate calcium in their diets and for postmenopausal women, who have a tendency toward decreased bone density. "One-third of the population gets only half as much calcium as they should," Genco says. "I think it's important to let women know that they're at risk for losing teeth if they don't address the risk of bone loss from menopause."

    The studies that have captured the attention of television and newspapers, however, are those that have linked periodontal disease to such killers as stroke and heart attack. Why there should be such a relationship is not yet fully understood, Genco says.

    Previous studies had shown that other infections--Chlamydia pneumoniae and ulcers--were connected with heart disease, he says. But only in the past 10 years have researchers begun to connect periodontal bacteria to heart and other systemic problems. "It's emerging. It's controversial. We don't yet have full data, but the evidence is accumulating and becoming more convincing," Genco says.

    In a study of the Pima Indians of Arizona, a population characterized by high levels of gum disease, Genco and his colleagues found that, among those with gum disease, the risk of heart attack was almost three times higher than for those with healthy gums. The Pima use very little tobacco, so the researchers could say with confidence that smoking was not a significant factor in their high rate of heart attacks.

    A subsequent study carried out at UB with Maurizio Trevisan, chair of the Department of Social and Preventive Medicine in the UB School of Medicine and Biomedical Sciences, found that although heart attack patients were heavily infected with all types of bacteria, the risk of infarction was significantly related to only three types of oral bacteria: Bacteroides forsythus, Porphyromonas gingivalis and Campylobacter rectus.

    Joseph J. Zambon, professor of periodontology and associate dean for academic affairs in the School of Dental Medicine, has been conducting related research on atheromas, the fatty nodules that form on the inner walls of arteries. Atheromas can cause heart attack by closing off the blood vessels that supply blood to the heart muscle, and can cause stroke if they break off and clog an artery in the brain.

    Traditional thinking, says Zambon, has it that atheromas are related to a variety of factors, such as high cholesterol levels, as well as diabetes. Now, he says, the idea is emerging that infections may have something to do with their formation. He posed the question, "Could oral pathogens be contributing to the formation of these deadly artery blockers?"

    To find out, he and his colleague, Violet Haraszthy, studied atheromas removed from the carotid arteries of hospital patients. By analyzing the DNA of the nodules, they determined that in about half the samples, periodontal pathogens were indeed present.

    That doesn't prove that the oral bacteria caused the blockage, Zambon notes. It could be that the nodule formed for other reasons, and oral bacteria accumulated in it as blood flowed past. But "you build up a body of evidence," he says. The next step will be a randomized clinical trial in which patients will take antibiotics to see whether that reduces the incidence of heart attack and stroke.

    "This is an emerging story," Zambon says. "The idea is that oral infections have a bigger role in systemic problems than we previously thought." And, he says, it's one that people need to keep tabs on as more is learned about that relationship. "Men, especially, don't appreciate the consequences," he says. "If people have the idea that gum disease might cause them to lose their teeth, they may not pay much attention; however, if they know it may cause them to have a heart attack or stroke, that may have more of an effect" on their health habits.

    Laurie C. Carter, associate professor of oral diagnostic sciences, has been working on a study similarly related to stroke. It's one that has immediate implications for what dentists do every day in the office.

    A panoramic X ray, she points out, images not only the teeth and jaw, but also the soft tissue of the neck down to the carotid blood vessels. Dentists routinely examine the teeth on such radiographs, but it's now clear that there's another clue to good health in those pictures. "You don't see the vessels," Carter says, "unless there's calcified atherosclerotic plaque present"-- the kind of blockages that could indicate a significant risk for stroke.

    "It's a totally silent disease," she says. "Stroke is the third-leading cause of death in the United States, so it's a public health problem of fairly wide scope. And very few people who suffer stroke have any advance indication that they're headed for trouble."

    Unless, that is, their dentist tells them that their carotid blood vessels look worrisome and they should see their primary physician. With ultrasound diagnosis, some of these patients have found stenosis--a constriction of the vessels--anywhere from 30 to 40 percent, all the way up to 99 percent. These patients are in critical danger and are taken into surgery within a week or two.

    Carter and her colleagues are now documenting this diagnostic tool. They are taking patients whose X rays show calcification for ultrasound diagnosis, and correlating the degree of stenosis found to the area of surface calcification on the X rays.

    "We can't go out and do a mass screening like we do for blood pressure," Carter says. "But if there is calcification, you know there is disease."

    Sara G. Grossi, clinical director of the Periodontal and Implant Research Center at UB, and her colleagues are studying lifestyle risk factors for gum disease, using data from the federal government's massive National Health and Nutrition Examination Survey. Analyzing data from nearly 6,500 survey subjects in that study, Grossi looked at alcohol consumption and antioxidant intake and discovered that both bear significant relationships to the development of gum disease. Her results replicated the findings from the school's own Erie County study that identified patterns of gum disease and dental decay.

ur studies indicated that the effects of smoking and alcohol on the body tissues are absolutely phenomenal," says Grossi. "It's important to have adequate intake of these antioxidants (such as vitamins A, C and E) in general, just to be able to neutralize free radicals and maintain a balance of health. We found that this effect was even more pronounced in individuals who were putting this to the greatest test, such as smokers."

    The lesson, she says, is that "diet plays a bigger role in chronic diseases and infections than we previously recognized. We are probably being a little naive ... thinking that because we eat three times a day we have an adequate diet, meaning one that is sufficient in nutrients. What this study showed is that diet and specific nutrients in the diet (such as calcium) are very important to building bone and skeleton tissue and maintaining oral health.

    "There is some intuitiveness to this, but the advantage we have in our current position is that these are the facts, and we are now empowered with this knowledge and can really utilize this information to our benefit. For example, in terms of children, we can make sure their intake of calcium is sufficient to support building a skeleton that is strong and will support them throughout their lives."

    Grossi's conclusion: "I like to say that science has taught me one thing--my mother was right!"


Scott Thomas is copyediting coordinator of the Buffalo News.




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