Authors: Carmen Cox
(NEW YORK) -- “It’s time for your annual X-rays.” This is what millions of Americans are told when they visit the dentist. But new research out of Yale finds dental X-rays may be linked to increased rates of brain tumors.
Meningioma is the most common type of brain tumors that originate in the brain and spinal cord, making up one third of these. People who were diagnosed with meningioma were compared with healthy individuals. They were asked how often they had the most common type of dental X-ray, called a bitewing, which involves placing an X-ray film between the teeth and shooting the film from outside of your cheek. In those who reported having this type of X-ray once a year or more the risk for meningioma was 1.4-1.9 times increased depending on their age.
Another type of dental X-ray, called the Panorex, that rotates around your head taking a picture of all of your teeth from outside your mouth was associated with an almost five-fold increase in rates of meningioma when the X-ray was performed before age 10. For those older than 10 there was a 2.7 to 3 fold increased risk when this X-ray was performed once a year or more.
Current recommendations by the American Dental Association do admit that there is little use for dental X-rays in healthy people without any symptoms, but still recommends X-rays of healthy children be taken every 1-2 years and every 2-3 years for healthy adults. The authors think these guidelines may need to be reevaluated in the wake of their findings.
Reactions to the study have been mixed. For critics, the design of the study has some serious flaws. 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, says Dr. Richard Besser, ABC News' chief health and medical editor.
“People with cancer are more likely to remember having dental X-rays,” explains Besser. “They are searching for some cause of their cancer and may incorrectly attribute it to any number of factors.” Dr. Besser also points out that the study failed to find any connection between having braces and risk for meningioma. “When you have braces you remember that clearly, and people who have braces on average undergo more x-rays than people without braces,” says Besser.
Dr. Alan G. Lurie, a Ph.D. radiation biologist who specializes in cancer induction and is president of the American Academy of Oral and Maxillofacial Radiology, agrees with Dr. Besser that 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?" Lurie says.
Other doctors see this as a strong study and think that it raises valid concerns. “The current study is well-done and confirms that even in the ‘modern era’ radiation exposure from repeated dental X-rays conveys an increased risk of these tumors,” says Dr. David Schiff of the Neuro-Oncology Center at the University of Virginia.
Overall, doctors are not surprised that dental X-rays could cause this type of tumor because the type of radiation that X-rays give off is known to be associated with brain tumors. “Ionizing radiation is the only well-accepted environmental risk factor for development of meningiomas," says Dr. Schiff.
However they warn that this study cannot prove that dental X-rays cause brain tumors. It can only reveal a possible association between dental X-rays and tumors.
Still, there are some important things people can do to minimize their exposure to dental X-rays. For example, patients can ask their doctors whether X-rays are completely necessary, or how much radiation will be delivered by the various options available.
“All health professionals should be thinking that for our patients, each exposure must be beneficial and we should be of a mindset to do the fewest exposures possible to obtain needed diagnostic information," explains Paul Casamassimo DDS, professor and chair of pediatric dentistry at the Ohio State University College of Dentistry and chief of dentistry at Nationwide Children's.
Overall, experts hope that as a result of this study the public gains new awareness of a potential risk and will take their concerns to their dentist.
Copyright 2012 ABC News Radio