Dr. K: Dental x-rays pose very little radiation risks

Some people worry that getting dental X-rays can cause cancer or birth defects. Today’s dental X-ray machines emit very low levels of radiation. They narrowly focus the X-ray beam so it passes through only your jaw and teeth. And they work fast. These advances all reduce the radiation exposure.

Increasingly, dentists are using digital dental X-rays. These devices store images in electronic files rather than on film. The high-resolution pictures require as little as 10 percent of the amount of radiation needed to create a traditional X-ray image.

Still, as a precaution, your dentist should cover your body with a lead apron when taking X-rays. This prevents up to 94 percent of the radiation from reaching your chest, abdomen and reproductive organs. That virtually eliminates the risk of birth defects, and your risk of cancer — except for your thyroid gland. To shield your thyroid gland, which is located in the front of your neck, you should also wear a lead collar while the X-rays are being taken.

How often you need dental X-rays depends on the state of your dental health. Adults with no oral health problems may get X-rays every two to three years. If you are at high risk for cavities or have a history of advanced gum disease, you may need X-rays more frequently. If you change dentists or see a specialist, bring your X-rays with you. That way, your new dentist won’t need to duplicate the ones you already have.

There’s a lot more to dental checkups than X-rays. Routine checkups also include a professional cleaning and an exam. Professional cleaning rids your teeth of hardened plaque that can build up in hard-to-reach places.

For most people, two checkups per year are enough. But if you have special dental issues or are at high risk for them, your dentist may recommend that you come in more often.X-rays have greatly improved the care your dentist gives you, just as they have improved the care you receive from your doctor. They allow your dentist to see problems that would be otherwise invisible. Like most powerful technologies that can improve our health, they do contain some risks. Fortunately, the machines that take dental X-rays today reduce those risks.

(Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.