April 11, 2012 - We recognize that many patients are concerned by the results of a study published in the scientific journal Cancer, which associates yearly or more frequent dental X-rays with an increased risk of developing meningioma. Resources and expert opinions cited by the American Dental Association, American Academy of Oral and Maxillofacial Radiology and the American Cancer Society lead Dr. Graber to question the validity of the Cancer study pending further research.
At the Dental Center of Huntington, we made the investment in Dexis digital X-ray technology in 2008 to minimize patient exposure to radiation. Dr. Graber uses previous radiographs whenever possible, and relies on new X-rays when necessary for diagnosis and treatment. In general, our office follows the American Dental Association recommendations, which suggests routine mouth X-rays every two to three years for healthy adults, every one to two years for children and every 1.5 to three years for teenagers. (Children require more frequent X-rays because of their developing teeth and jaws and increased likelihood for cavities.)
Below are two experts' takes on the study's potential flaws:
According to Dr. Alan Lurie, a Ph.D. radiation biologist who specializes in cancer induction and is president of the American Academy of Oral and Maxillofacial Radiology, the study has a serious flaw. “They’re asking people to remember (in some cases) a couple of radiographs they had 30 years earlier when they were kids. They’re not going to be able to tell you what kind of X-ray machine was used…what kind of film, were there any retakes?"
Dr. Lurie adds that radiation levels from dental X-rays when some of the participants were younger was much greater than is used now.
"They found a small risk (from) a pair of bitewings, but not a full mouth series, which is multiple bitewings. That inconsistency is impossible to understand to me," said Lurie.
The main weakness is the failure of the researchers to obtain any of the patient’s dental records to verify that the number of X-rays they reported having was true, echoes Dr. Richard Besser, ABC News' chief health and medical editor.
The following press release was issued on April 10, 2012 by the American Dental Association:
The American Dental Association (ADA) is aware of a recent study that associates yearly or more frequent dental X-rays to an increased risk of developing meningioma, the most commonly diagnosed brain tumor. The ADA’s long-standing position is that dentists should order dental X-rays for patients only when necessary for diagnosis and treatment. Since 1989, the ADA has published recommendations to help dentists ensure that radiation exposure is as low as reasonably achievable.
The ADA has reviewed the study and notes that the results rely on the individuals’ memories of having dental X-rays taken years earlier. Studies have shown that the ability to recall information is often imperfect. Therefore, the results of studies that use this design can be unreliable because they are affected by what scientists call "recall bias." Also, the study acknowledges that some of the subjects received dental X-rays decades ago when radiation exposure was greater. Radiation rates were higher in the past due to the use of old X-ray technology and slower speed film. The ADA encourages further research in the interest of patient safety.
As part of the ADA’s recommendations to minimize radiation exposure, the ADA encourages the use of abdominal shielding (e.g., protective aprons) and thyroid collars on all patients. In addition, the ADA recommends that dentists use E or F speed film, the two fastest film speeds available, or a digital X-ray.
In addition to the X-ray recommendations, the ADA’s Council on Scientific Affairs will publish clinical guidance on the use of cone-beam computed tomography in an upcoming issue of The Journal of the American Dental Association. The ADA will share these recommendations as soon as they are available.
Dental X-rays are valuable in helping dentists detect and treat oral health problems at an early stage. Many oral diseases can’t be detected on the basis of a visual and physical examination alone, and dental X-rays are valuable in providing information about a patient’s oral health such as early-stage cavities, gum diseases, infections or some types of tumors. How often dental X-rays should be taken depends on the patient’s oral health condition, age, risk for disease and any signs and symptoms of oral disease that the patient might be experiencing.
The ADA encourages patients to talk to their dentists if they have questions about their dental treatment. As a science-based organization, the ADA fully supports continuing research that helps dentists deliver high-quality oral health care safely and effectively.