Do Dental X-rays Really Cause Brain Tumors?
A recent article in the journal Cancer suggested that having routine bitewing x-rays at dental checkups may cause a certain type of benign brain tumor (a meningioma). This article was picked up by the New York Times and then reported by most major news media including CNN and Fox News. Using dental x-rays in my practice every day, this article naturally caught my attention. Here’s how the study was performed. Two groups of patients between the ages of 20 and 79 were interviewed. They were asked to remember how many dental x-rays they had received at the following ages: less than 10, between 10 and 19, between 20 and 49, and over 50. Three types of x-rays were examined; bitewings (single x-rays), panoramic films (about 20 seconds each), and full mouth surveys (up to 21 individual x-rays). Statistical analyses were then performed to compare the recalled number of x-rays received with the presence of tumors. Researchers found no differences in the memories of patients regarding panoramic films or full mouth surveys. They did however report that participants with meningiomas remembered having more bitewings than their counterparts.
This study has serious flaws in its design and it produced some irrational results that cannot be explained, even by the researchers. Its major weakness was in the requirement that participants recall their own radiographic history from decades before, sometimes more than 50 years previous. Can you remember how many bitewings you had before you were 10? How about between 10 and 19? How about in the most recent 10 years? The study might have been more credible had actual dental records been used, but they were not. The data was obtained strictly from the memories of those interviewed. Unexplainably, the study failed to identify any relationship between patients who reported more panoramic films (3 times more radiation) or full mouth surveys (21 times more radiation) and the presence of brain tumors. Claiming a relationship between the lower radiation bitewings and brain tumors but no similar finding for the higher radiation films makes absolutely no biological sense.
My point is not to discount the importance of x-ray safety. All dentists are trained in radiation hygiene and subscribe to the ALARA principle (As Little As Reasonably Achievable). We are now using faster equipment, more sensitive films and sensors, better collimation, lead aprons, thyroid collars, and digital equipment (which greatly reduces the need for retakes) than ever before. These improvements have resulted in a 60% reduction in radiation exposure since I got my license in 1989. Today’s patients receive the equivalent of only one additional day’s worth of background radiation (from the sun) each time they get a bitewing and only three additional days’ for a pano.
X-rays remain a crucial diagnostic tool in today’s dental practice. I myself have discovered half a dozen tumors in my own patients using the very x-rays being demonized in this study. We dentists want to provide the safest procedures possible and welcome any research that actually helps our patients. This article and the TV news reports that followed did nothing more than provide an attention-grabbing headline.
NOTE: The author, Dr. Greg Jorgensen, is a board-certified orthodontist who is in the private practice of orthodontics in Rio Rancho, New Mexico (a suburb on the westside of Albuquerque). He was trained at BYU, Washington University in St. Louis, and the University of Iowa in the United States. Dr. Jorgensen’s 25 years of specialty practice and 10,000 finished cases qualify him an expert in two-phase treatment, extraction and non-extraction therapy, functional orthodontics, clear aligners (Invisalign), and multiple bracket systems (including conventional braces, Damon and other self-ligating brackets, Suresmile, and lingual braces). This blog for informational purposes only and is designed to help consumers understand currently accepted orthodontic concepts. It is not a venue for debating alternative treatment theories. Dr. Jorgensen is licensed to diagnose and treat patients only in the state of New Mexico. He cannot diagnose cases described in comments nor can he select treatment plans for readers. Because he has over 25,000 readers each month, it is impossible for him respond to all questions. Please read all of the comments associated with each article as most of the questions he receives each week have been asked and answered previously. The opinions expressed here are protected by copyright laws and can only be used with written permission from the author.