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X-Rays: Avoiding Overexposure
Asking a dentist to work without X-rays, one says, is like asking an auto mechanic to find what's wrong with your engine without lifting the hood. X-rays provide a valuable way to detect and track dental disease. But overexposure should be avoided, especially by children and women of child-bearing age.
One source of unnecessary radiation exposure: switching dentists. Generally, when you visit a dentist as a new patient, he or she will want to take a full-month series of images, a baseline from which to spot changes. Since a full-mouth series need be done only every five to eight years, try to arrange for your previous dentist to send recent X-rays or duplicates.
A full series consists of about 18 images. Most films will be “periapical” X-ray - each shows several entire teeth from root to crown with the surrounding tissue. They're useful for diagnosing fractures, abscesses, impactions, bone-loss patterns and cysts and tumors of the jaw not otherwise visible. A few images will be "bitewing" shots—each captures on a single film the crowns of a few upper and lower teeth, usually on the sides and at the back of the mouth. Bitewings are especially good for seeing cavities between teeth and bone loss due to gum disease. Least useful are "panographic" X-rays, sweeping panoramic views without much detail.
Modern equipment, "faster" film, and the leaded aprons used in dental offices all limit patients' exposure to X-rays. The American Dental Association estimates that a full-mouth series done with modern equipment exposes a patient to 13 millirems of radiation. For comparison, the average person receives about 300 millirems a year from the natural environment, and workers whose occupation involves radiation are permitted 5000 millirems of whole-body exposure a year.
Two recent developments, if widely adopted, are likely to limit exposure further:
- Conventional X-rays. These can be scanned into computers—just like vacation snapshots. Once digitized, the images are stored compactly and transmitted efficiently- on diskette or over telephone lines—to other dentists or to insurance companies. This can reduce the need to take new X-rays.
- Direct digital radiography. This system, now found mostly in university-based clinics, replaces the film with a much more sensitive device that requires far less radiation and can highlight subtle changes.
Article provided by Consumer Reports magazine.