Dr. W. Mark Donald, a general dentist in Louisville, Miss., and spokesman for the Academy of General Dentistry, says that, in general, adults and children should have two to four "bite wing" X-rays twice a year to make sure all incipient cavities and other problems are caught early.
But he and other dentists caution that this is just a general recommendation and that the actual frequency of X-rays varies significantly among patients, depending on the patient's history of dental problems and the dentist's judgment.
If a patient is at low risk for dental problems, never has new cavities, eats a healthy diet and practices excellent oral hygiene - brushing and flossing daily - he or she may need X-rays only once every two to three years, said Dr. Dara Cunnion, a pediatric dentist at the Boston University School of Dental Medicine.
But you should be assertive in talking to your dentist about X-rays, and how often you really need them, said Frank Masse, a retired MIT nuclear physicist who now runs a consulting service for hospitals and medical clinics. Masse said he allows his dentist to take X-rays "only if there is a real need," adding that "it's been many, many years since I had a whole-mouth exam."
The good news is that dentists now use "fast speed film or digital X-rays that can decrease exposure by 80 percent," said Cunnion. If the dentist uses the fastest film available, the radiation exposure from four bite wings is roughly equivalent to about two days of natural, background radiation from simply living on earth, or about 20 to 38 microsieverts.
That "is not a lot of exposure," Masse said. But "my advice is the same with any radiation - be cautious. Do it only if necessary - if it's likely to yield some important information."
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