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Medicine News Science

Dental X-Rays Linked To Common Brain Tumor 248

redletterdave writes "A new study suggests people who had certain kinds of dental X-rays in the past may be at an increased risk for meningioma, the most commonly diagnosed brain tumor in the U.S. Dr. Elizabeth Klaus, the study's lead author and a professor at the Yale School of Medicine, discovered that dental X-rays are the most common source of exposure to ionizing radiation — which has been linked to meningiomas in the past — and that those diagnosed with meningiomas were more than twice as likely as a comparison group to report ever having had bitewing images taken. And regardless of the age when the bitewings were taken, those who had them yearly or more frequently were between 40 percent and 90 percent higher risk at all ages to be diagnosed with a brain tumor."
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Dental X-Rays Linked To Common Brain Tumor

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  • Re:Cancer... (Score:3, Informative)

    by Anonymous Coward on Tuesday April 10, 2012 @10:34AM (#39630747)

    My father was a dental technician (he made dental crowns) and he always refused to get x-rays when he went in for his check-ups. My physics professor in undergrad told me the same thing - only get dental x-rays when absolutely necessary. Bone does a good job of scattering x-rays all over the place, and your skull and jaw, believe it or not, are composed of a great deal of dense bone.

  • by houstonbofh ( 602064 ) on Tuesday April 10, 2012 @10:40AM (#39630839)
    Mobile phones do not release Ionizing Radiation. They release Radio Waves. These are different things. Really... You can take off your tin foil hat to make calls again.
  • by houstonbofh ( 602064 ) on Tuesday April 10, 2012 @10:41AM (#39630859)
    Because it is bouncing off your teeth and jaw so the cap would keep it in.
  • Flawed Study (Score:5, Informative)

    by blahbooboo ( 839709 ) on Tuesday April 10, 2012 @10:46AM (#39630929)

    This is a very flawed study that doesn't account for many things including a) It's based on patients "memories" of when they got x-rays and not actual dates b) Doesn't account for the dramatic reduction in amount of rays needed for the images in the last 20-30 years.

    Proof? Check this far better article http://articles.boston.com/2012-04-10/metro/31313701_1_x-rays-tumor-risk-radiation-exposure [boston.com]

  • by drerwk ( 695572 ) on Tuesday April 10, 2012 @11:31AM (#39631565) Homepage

    So, not that huge an increase. Actually 46% is a huge increase.

    They never seem to show the error bars. We are looking at a sample of 15. Not knowing anything else, one might assume Poisson statistics in which case the 1 sigma error is 1/sqrt(sample), so about 25%.
    This means that 66% of the time, if one were to run the exact same test, one would get results that varied by plus or minus 4 events. The difference between a sample of 15 and a sample of 21 can be expected about half the time.
    It really takes the urgency out of - OMG a factor of 46%.
    http://en.wikipedia.org/wiki/Poisson_distribution [wikipedia.org].

  • by FrootLoops ( 1817694 ) on Tuesday April 10, 2012 @11:35AM (#39631627)

    According to the EPA [epa.gov] (and other places), radio waves are firmly in the non-ionizing range whereas x-rays are definitely in the ionizing range. You'll have to provide some evidence that near field effects increase radio wave energy sufficiently to shift the radiation into the ionizing range with cell phones; I couldn't find any, and it's a strong claim to make. Considering the lack of unambiguous cell phone/cancer links I doubt such evidence exists.

  • Re:Cancer... (Score:5, Informative)

    by Zibodiz ( 2160038 ) on Tuesday April 10, 2012 @11:50AM (#39631925)
    That's a total lie. They use exactly half. Source: I'm a certified dental x-ray technician.
    'New' digital sensors require the same amount of X-Ray radiation, but for half the amount of time (for bitewings, that's about 100ms instead of 200ms), but since they're so quick to scan in (i.e. the Dentist doesn't have to wait for them to develop), if they aren't exactly perfect, dentists will often ask for re-takes. The average was 5 or 6 images on each patient. I was pretty good and usually only had a re-take every 3rd patient or so, but the other x-ray technician I worked with would often take 4 or 5 re-takes on a single patient. All-in-all, that means they got more radiation than if they had just gotten the traditional x-rays.
    I should point out, though, that the Dentist told every patient (and told us to tell them, as well) that they only get 1/100th of the radiation. It's just a party lie.
    As far as the 'pointed beam' you're talking about, that hasn't been improved, ever. The cone is just as large as it's always been. If the technician stands in the room (as my co-worker often did), they're just stupid. In fact, according to ADA recommendations, X-Ray techs are supposed to wear dosimeters. Most dentists are too cheap to buy them, though.
    The 'Bitewing' x-rays that this article is about are exactly the kind that are close to your cheek. There are 3 types of dental x-rays: Bitewings, which shoot the radiation between your molars and premolars, and are used to diagnose cavities between yoru teeth. PA's, which are used to view your entire tooth, including the entire root and an area of bone beyond it. These are useful for diagnosing a toothache, because if the toothache is caused by an infection at the apex of your root, it will be visible. That, in turn, means a root canal. The third is a Panoramic, which is the kind that wraps around your entire head, and shows all of your teeth in one shot. These are beneficial for things like getting an 'aerial view'; they don't show a lot of detail (not enough to diagnose a cavity), but will show things like impacted wisdom teeth, and are useful for Orthodontists.
  • by digitig ( 1056110 ) on Tuesday April 10, 2012 @11:56AM (#39632013)
    I think you will find that people died of brain tumours even before the mobile phone was invented. What was your point?
  • Re:not sure (Score:5, Informative)

    by bcrowell ( 177657 ) on Tuesday April 10, 2012 @01:01PM (#39633175) Homepage

    >> I'm a dental student, and I have been taught that - with modern equipment - exposure to radiation from 2 bitewings is about the same as half a day of ski holiday.

    >These comparisons are always misleading, because they ignore the density of the radiation received. Radiation from half a day of ski holiday is diffused over your entire body. The radiation from bite wing X-rays is concentrated on your teeth and skull. The concentration matters. Let's use a better analogy. The energy at the focal point of a magnifying glass might be one-hundredth the amount of energy you get from standing out in the sunshine. But because that energy is concentrated into a small point, it will burn your skin.

    Unsurprisingly, the dental student's professor knows more about this than you do. The professor's analogy is the correct one. Yours is the incorrect one.

    When x-rays cause cancer, it's a statistical process. Each x-ray photon has some small probability P of damaging a cell's DNA in such a way as to make it cancerous.

    When you go skiing in the mountains, you're exposing yourself to more cosmic rays than you get at sea level. These are high-energy charged particles, not x-ray photons, but the statistical nature of the process is the same.

    When you burn your skin with a magnifying glass, there is nothing statistical about the process. The outcome is deterministic. You're simply transporting x amount of energy into a certain piece of your flesh, raising its temperature by y degrees.

    In case it matters, I have a PhD in physics, my field is nuclear physics, and I have worked with ionizing radiation a lot.

    The only thing I would add to the correct information that the GP related from his/her professor is that in addition to the possibility of causing cancer, radiation can also make you healthier, via a well-documented effect called radiation hormesis. The usual interpretation (which is hard to test empirically) is that the radiation stimulates your cells' damage-control mechanisms. At the very low doses we're talking about, the evidence from controlled animal studies is that the net effect on your health is positive, because the hormesis effect is orders of magnitude stronger than the negative effects of the radiation.

The intelligence of any discussion diminishes with the square of the number of participants. -- Adam Walinsky