Dental X-rays linked to common brain tumor
The American Dental Association (ADA) says that it 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.
Meningioma, the most common primary brain tumor in the United States, accounts for about 33 percent of all primary brain tumors. The most consistently identified environmental risk factor for meningioma is exposure to ionizing radiation. In the largest study of its kind, researchers from Brigham and Women's Hospital (BWH), Yale University School of Medicine, Duke University, UCSF and Baylor College of Medicine have found a correlation between past frequent dental x-rays, which are the most common source of exposure to ionizing radiation in the U.S, and an increased risk of developing meningioma. These findings are published in the April 10, 2012 issue of Cancer.
"The findings suggest that dental x-rays obtained in the past at increased frequently and at a young age, may be associated with increased risk of developing this common type of brain tumor," said Elizabeth Claus, MD, PhD, a neurosurgeon at BWH and Yale University School of Medicine at New Haven. "This research suggests that although dental x-rays are an important tool in maintaining good oral health, efforts to moderate exposure to this form of imaging may be of benefit to some patients."
Claus and her colleagues studied data from 1,433 patients diagnosed with meningioma between 20 and 79 years of age between May 2006 and April 2011 and compared the information to a control group of 1350 participants with similar characteristics. They found that patients with meningioma were twice as likely to report having a specific type of dental x-ray called a bitewing exam, and that those who reported having them yearly or more frequently were 1.4 to 1.9 times as likely to develop a meningioma when compared to the control group. Additionally, researchers report that there was an even greater increased risk of meningioma in patients who reported having a panorex x-ray exam. Those who reported having this exam taken under the age of 10, were 4.9 times more likely to develop a meningioma compared to controls. Those who reported having the exam yearly or more frequently than once a year were nearly 3 times as likely to develop meningioma when compared to the control group.
"It is important to note that the dental x-rays performed today use a much lower dose of radiation than in the past," said Claus.
According to background information in the study, The American Dental Association's statement on the use of dental radiographs emphasizes the need for dentists to examine the risks and benefits of dental x-rays and confirms that there is little evidence to support the use of dental x-rays in healthy patients at preset intervals.
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.