| Nearly all medical procedures have risks and benefits, and dental X-rays are no exception. The benefits are well known: X-rays help dentists diagnose relatively common disorders such as cavities, periodontal disease and infections. Without this ability to see inside a tooth and beneath the gums, more disease would go unchecked, patients would experience more pain and discomfort and more teeth would be lost because proper treatment couldn't be started in time. "Also, if radiographs [X-rays] are not taken, the work can be compromised and will result in more expensive and complicated procedures at a later stage," says Neill Serman, B.D.S., D.D.S., professor and head of the division of oral radiology at Columbia University School of Dental and Oral Surgery in New York. For these reasons, dentists consider X-rays one of their best diagnostic tools in helping patients maintain good oral health. But dental X-rays are not without risk. The risk is tiny compared with the huge diagnostic benefit. Still, with technological advances, people are absorbing increasing amounts of radiation from their environment, so radiation should be limited whenever possible. "In order to expose patients to as little radiation as possible, most dentists will ask new patients how recently they had dental X-rays taken," Dr. Serman says. "If patients were recently radiographed [X-rayed] in another office, the dentist will attempt to obtain copies of those radiographs." Dentists are aware of the possible dangers associated with X-rays and bear this in mind when they recommend X-rays to patients, he said. X-rays are a form of energy that's absorbed in your body. Large amounts of radiation have been shown to be associated with cancer and changes in chromosomes. In the head and neck, areas exposed to dental radiation, X-rays increase the risk of damage to or cancer of the lens of the eye, thyroid, salivary glands, bone marrow and skin. No one knows the exact effects of low-dose radiation, which is the type used in dental X-rays. However, the effects of radiation exposures are cumulative, meaning the effects depend on the total amount you have absorbed in your life. The small amount of radiation exposure that a patient receives from dental X-rays has never been proven to cause cancer of the lens of the eye, thyroid, salivary glands, bone marrow or skin. Nevertheless, every little bit counts. Dentistry has made great advances in lowering the radiation dose administered. For example, in the 1930s and 1940s, the irradiating cone, which emits the radiation, was huge, covering most of the head and neck. Now, the diameter of the cone is very small, less than 3 inches, so radiation is only pointed at the small spot where the X-ray film is located in your mouth. Also, in the past, the exposure lasted several seconds, whereas now, the exposure times are set at tenths of seconds. Many of the critical organs that might show radiation effects, such as the breasts and gonads, are not threatened during a dental exam because they are not in the path of radiation. In addition, the patient is covered with a lead apron, which blocks radiation. There are several procedures that cannot be done successfully without the help of X-rays. For example, to successfully perform root canal treatment, a few X-rays are required to determine that the root canal has been filled properly. How You Can Increase Safety Most of the work to reduce the risk of X-rays is already being done. For example, frequent improvements have decreased the amount of X-ray scatter to eliminate unnecessary exposure. Faster film speed has dramatically reduced the amount of radiation exposure to the patient by reducing exposure time. Patients can and should talk with their dentists about how often they need X-rays and why. It used to be that X-rays were given on a predetermined schedule. Current guidelines, however, require that X-rays be given only when needed to diagnose a suspected problem. A dentist should never prescribe X-rays unless a clinical examination has been done to determine the number and type of X-rays required. Of course, the number and frequency of X-rays needed varies from person to person. Children often need more frequent X-rays because their teeth are prone to cavities. People with a lot of dental fillings and other restorations also need X-rays more often because decay can easily occur beneath or between existing fillings and do a great deal of damage before it can be detected. People with periodontal (gum) disease will need X-rays more often to monitor the course of their disease. Radiation to the rest of the body can be reduced by covering the patient with a lead apron and by using the fastest film speed available. D-speed film was available until 1982. That year, E-speed film came onto the market. This reduced the exposure time by about 50% so the amount of radiation the patient recieved was reduced by 50%. In 2001, F-speed film became available, and this reduced the amount of radiation to the patient by a further 20%. "Thus, the amount of radiation that the patient received from dental radiation is minimal and has been dramatically reduced over the past few years," Dr. Serman says. "One can safely say that patients are receiving less radiation from dental sources than a few years ago and the benefits generally far outweigh the possible risks." ©2001-2007 Aetna All rights reserved. Reviewed by the faculty of Columbia University College of Dental Medicine | 
