Your dentist's x-ray equipment may bear a closer look.

RODALE NEWS, EMMAUS, PA—Our exposure to radiation is now seven times higher than it was in the 1980s. While most of that comes from CT scans, body X-rays, mammograms, and other forms of medical imaging, there's another common source of radiation you could be getting every six months when you go in for a teeth cleaning.

THE DETAILS: In general, the dental industry is developing new methods and practices that expose people to lower levels of radiation now than ever before. "It's in line with, or even more advanced than other fields of medicine," says Erika Benavides, DDS, PhD, clinical assistant professor in the department of periodontics and oral medicine at the University of Michigan School of Dentistry. The problem is that dentists themselves don't seem eager to invest in all those new low-radiation methods.

Last fall, a New York Times investigation revealed that about 70 percent of the nation's dentists are still using older, D-speed dental film, which exposes people to nearly 60 percent more radiation than newer, faster F-speed films. And their reluctance to upgrade to newer technologies goes against the recommendations of the American Dental Association (ADA) that dentists use the fastest-speed film available. "Some clinicians will tell you that they don't like F-speed film because it looks like it's not as clear as D-speed film," says Dr. Benavides. But, she adds, studies have shown that F-speed films are just as good as D-speed films at providing the clear images dentists need to accurately diagnose a condition. "When it comes to diagnosing disease, it performs just as well," she says.

On the other end of the technology spectrum, a small percentage of tech-oriented dentists and orthodontists are eagerly embracing a new form of imaging equipment called cone-beam computed tomography, or CBCT, a type of scan that gives dentists three-dimensional images of a patient's head and mouth. Although they're intended to help treat and diagnose complicated dental problems, some orthodontists are using them for simple procedures, such as putting on braces. In doing so, they're exposing children and adolescents to unnecessary, and somewhat high, levels of radiation, concluded some of Dr. Benavides' colleagues from the University of Michigan, in a recent issue of the British journal Dentomaxillofacial Radiology. In their a review of CBCT safety, the authors noted that CBCT scans can expose children to anywhere from 87 to 206 microsieverts of radiation, compared to the 4 to 40 microsieverts children are exposed to with traditional two-dimensional scans.

In most cases, dentists opt for CBCT scans because they're easier, faster, and believed to be more accurate than 2-D film. "With braces, though, this is not one of those cases that you should use it just because it's easier," says Dr. Benavides. Children are five to 10 times more sensitive to radiation than adults, and Dr. Benavides says that any benefits of using such high-radiation equipment should be balanced against potential risks.

WHAT IT MEANS: So should you avoid all dental X-rays? It may seem tempting, but doing so may deprive your dentist of important diagnostic info. In fact, some dentists may worry about just that. "We want to make dentists aware of these increasing amounts of radiation exposure," says Dr. Benavides, "but if you have a very apprehensive patient, it could result in people who do not want these scans even when they might benefit from them."