April 10, 2012 -- Getting frequent dental X-rays appears to increase the risk for a commonly diagnosed brain tumor, a new study finds.
Exposure to ionizing radiation -- the kind found in X-rays -- is the biggest known environmental risk factor for largely non-malignant meningioma brain tumors. Routine dental X-rays are among the most common sources of radiation for most healthy people in the U.S.
The new study suggests that performing frequent X-rays may expose patients to unnecessary risk.
"These findings should not prevent anyone from going to the dentist," says lead researcher and neurosurgeon Elizabeth B. Claus, MD, PhD, of Yale University School of Medicine and Boston's Brigham and Women's Hospital. "But it appears that a large percentage of patients receive annual X-rays instead of every two to three years, which is the recommendation for healthy adults."
Dental X-ray, Benign Brain Tumors
While the vast majority of meningiomas are non-malignant, they often grow to be very large and can cause a wide range of potentially serious symptoms, including vision and hearing loss, frequent headaches, memory loss, and even seizures.
They are the most frequently diagnosed brain tumors among adults in the United States, accounting for about a third of all primary brain and central nervous system tumors.
Several small studies have suggested a link between cumulative dental X-ray exposures and meningiomas, but the findings were inconclusive.
In the newly published study -- the largest ever to examine the question -- people who reported having "bitewing" X-rays at least yearly were found to have a 40% to 90% greater risk of meningioma.
The study shows an association but does not prove a cause-effect relationship.
The study included about 1,400 meningioma patients between the ages of 20 and 79 when they were diagnosed between the spring of 2006 and the spring of 2011.
When the patients' self-reported dental histories were compared to adults with similar characteristics who did not have the brain tumors, lifetime exposure to either bitewing or panoramic dental X-rays -- which include the upper and lower jaw -- was significantly associated with meningioma risk. This risk was higher in people who received panoramic X-rays when they were younger than 10.
The meningioma patients were more than twice as likely as the adults without brain tumors to have had dental X-rays at some point during their lives, Claus tells WebMD.
The study appears in the April 10 issue of the American Cancer Association journal Cancer.
Annual Dental X-rays Not Recommended
The American Dental Association responded to the study in a written statement, noting that the group has long called on its members to order dental X-rays only when necessary. To minimize radiation exposure, the group recommends using protective aprons and collars and the use the fastest film speeds available or a digital X-ray.
“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,” the statement reads.
Claus tells WebMD that the American Dental Association recommends healthy adults receive routine mouth X-rays every two to three years. Dental X-rays are recommended every one to two years for children and every 1.5 to three years for teens. Children often require more X-rays than adults because of their developing teeth and jaws and increased likelihood for cavities.
Neurosurgeon Michael Schulder, MD, agrees that the newly published findings make a good case for limiting the frequency of dental X-rays whenever possible.
Schulder is vice chairman of the department of neurosurgery at the Cushing Neuroscience Institute, which is part of the North Shore-LIJ Health System in Manhasset, N.Y.
"The chance of these tumors arising in patients who were X-rayed yearly was low," he notes in a news release. "Nonetheless, dentists and their patients should strongly consider obtaining X-rays less often than yearly unless symptoms suggest the need for imaging."