Dental X-rays linked to the most common type of brain tumor

One of the most uncomfortable aspects of your dental visit has just been linked to brain tumors. Research published in this week's issue of Cancer reveals that patients with meningioma — the most commonly diagnosed (but usually benign) brain-growth in the U.S. — were more than twice as likely as people without the tumor to have had a bitewing X-ray performed at some point in their lives.

It's worth pointing out right away that this study's findings are no excuse to skip out on regular visits to your dentist — or even to avoid having dental x-rays performed. Much more important, explain the researchers, is that you be mindful of your personal x-ray history, keep tabs on how frequently you have dental x-rays performed, and understand the circumstances under which your dentist has them ordered:

"These findings should not prevent anyone from going to the dentist," explained lead researcher and neurosurgeon Elizabeth B. Claus, an MD/PhD at Yale University School of Medicine, to WebMD. "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."

Claus and her team arrived at this conclusion after collecting self-reported lifetime dental X-ray histories from 1,433 meningioma patients, along with those of 1,350 people without brain tumors. The researchers found that study participants with tumors were more than twice as likely to report having ever had a bitewing examination; likewise, those who had bitewing examinations performed at least once a year were at 40—90% higher risk at all ages of being diagnosed with a brain tumor.

What's a bitewing examination? If you've ever had one, chances are you remember it. A bitewing x-ray is what a dentist uses to get a closer look inside your rearmost molars. This requires you to chomp down on a little piece of plastic that has a nasty way of poking into your gums and flipping the switch on you tear ducts.

So what's causing the tumors? It's tempting to tie them back to the ionizing radiation being pumped out by the x-rays, and while the evidence for this connection is certainly strong, the findings —strictly speaking — cannot prove that. For now, Claus says that there are two things you should keep in mind when interpreting her team's results. According to Time:

First, while most of the people in the study were diagnosed in recent years, their dental X-ray history stretched back a decade, if not more, to a time when ionizing radiation levels were much higher in dental X-rays than they are now. (The mean age of those with the tumors was 57.5 years.) Second, the study compared cases of meningioma to similar controls, rather than asking people about their dental X-ray history and then following them to see who developed meningiomas and who did not.

In other words: this study tells only part of the story; what's more, the data that supports a causative link between dental x-rays and meningiomas (namely the fact that ionizing radiation levels were higher in the past than they are now) also suggests that these x-rays are actually safer today than they were before.

Read more about the team's findings over at Time Magazine.

Read the researchers' report in its entirety in this week's issue of Cancer (no paywall).
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