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A new study suggests that dental X-rays may increase the risk of the most common kind of brain tumor. However, experts say the risk of these mostly non-cancerous growths is still very small. The study compared about fourteen hundred patients with a brain tumor called a meningioma to a group without brain tumors. Dr. Elizabeth Claus of Yale University led the study. She says it found that those with the tumors were about twice as likely to report having had a common kind of X-ray, called a bitewing. The link was greater with a kind of imaging called a panoramic X-ray. There was up to five times the risk, depending on age or how often the X-rays were taken.Dr. Claus points out that in this study, the people were generally in their fifties or older. They were asked to remember X-rays they might have had many years earlier. So there is a chance they might have under-reported or over-reported how many dental X-rays they had. Dr. Claus says she does not want to scare people away from dental visits. In her words: "The big take-home message is, keep going to the dentist. But have a conversation with your dentist about whether you might be able to reduce the number of X-rays that you receive." Her research paper appears in the American Cancer Society's journal, Cancer.During dental procedures, and even when people brush their teeth, mouth bacteria often enter the blood system. A popular belief is that gum disease can lead to heart attacks. But the American Heart Association recently published a statement saying there is no scientific proof. The statement, appearing in its journal Circulation, says gum disease has not been proven to cause heart disease or stroke. And, it says, treating gum disease has not been proven to prevent them. There is also not enough evidence to know whether brushing and flossing regularly can prevent heart disease.A committee of heart doctors, dentists and infectious disease specialists considered five hundred journal articles and studies. They say there is not enough evidence at this time to confirm a cause-and-effect relationship between gum disease and heart disease. Both diseases are often found in the same patient. But the experts say this is possibly because of risk factors common to both diseases. People who do not pay attention to risk factors like smoking, diabetes or high blood pressure may not pay close attention to their oral health either. For VOA Special English, I'm Carolyn Presutti. (Adapted from a radio program broadcast 25Apr2012)