Dental X-Rays Linked To Common Brain Tumor

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."

Comments

not sure

[Anonymous Coward]

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. You really need to take a lot x-rays to expose patients to significant more ionizing radiation than they receive from nature itself.

Re:not sure

[Remus Shepherd]

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

Masters' in physics here with a similar background to yours.

My point is that the statistical likelihood of damage due to radiation depends upon its flux. For the same amount of incident energy, the flux you receive across your entire body is lower than if the same energy were collimated and aimed at your skull. The same number of photons in a smaller area increases the risk in that area. So saying that a dental X-ray has the same energy as a full-body soak in low-level radiation is deceptive. The dental X-ray is over a much smaller area, has a higher incident flux, and therefore has a larger chance to cause damage in that specific region.

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.

And this makes me suspicious of your credentials, because hormesis is an effect usually only talked about by snake oil salesmen. It's not a reliable effect, and there's a good bit of argument against it existing at all. Even if it does exist it is not something you want to play with, as a very small change of dose can drive your exposure from 'beneficial' to 'really dangerous'. If you're relying on hormesis to keep you safe then you are begging for disaster.

I've often wondered...

[Daetrin]

They give you this big heavy blanket (lined with lead? I dunno) to lay across your body when they do the x-ray. They seem to think it's important to block off the areas they're not actually imaging. So why don't they give you something similar to lay across the top half of your face and head? Obviously it wouldn't stop everything, but you'd think it would help at least a little.

CMOS imaging?

[AmonRa1979]

Any word on whether there was a decline in this type of tumor when CMOS x-ray imaging started being used in dentistry? Using CMOS rather than film supposedly requires less exposure time or less x-ray intensity in order to obtain an image comparable to film. I see the article does comment on the decreased intensity of x-ray source now as compared to a decade or so ago, but unless they couldn't readily identify this type of tumor back then, then I would expect to have seen a decline in this type of tumor as well.

Re:And it took this long to "make the connection"?

[DrData99]

Well, I know that it is uncommon on /. to actually RTFA, but:
>>
The lack of association with full-mouth X-rays led one expert to question the connection.

"They found a small risk (from) a pair of bitewings, but not a full mouth series, which is multiple bitewings. That inconsistency is impossible to understand to me," said Dr. Alan Lurie, president of the American Academy of Oral and Maxillofacial Radiology.
>>
So a small risk (increase from 15/10,000 to 22/10,000) caused by a pair of bitewings disappears when you do more?

I don't think so...

Re:And it took this long to "make the connection"?

[Anonymous Coward]

"It is basic chemistry, nothing with a wavelength longer than UV can ionize a molecule."

In the far field. In the near field, the electric field is very high. You can light up a straight old neon tube with a 27MHz walkie talkie.

re: taking dentistry for granted

[King_TJ]

I'm not trying to marginalize your point, but at the same time? It seems to me that dentistry is one of the areas of medicine with the least amount of oversight or "checks and balances" to ensure patients are getting what they pay for.

For example, I went to a dentist as a teenager to have an impacted wisdom tooth extracted. The oral surgeon recommended that I have "all 4 wisdom teeth pulled at the same time, since there was a good chance the others weren't all going to come in properly anyway - and it would be less painful if I only went through one extraction". I went with his recommendation, only to find that a couple years later, I had cavities in the back of a couple of my teeth, where they faced those wisdom teeth. Apparently, their enamel was damaged in the tooth extraction process, causing them to get cavities. So then I had those filled, but I remembered thinking the whole process was a bit questionable at the time, because he had a young dental assistant working with him, who he asked to mix up the amalgam filling material for him. I remember him looking at it and questioning her about whether she mixed something up enough because it didn't look quite right, stirring it around a bit in the container she was holding, and ultimately going ahead and using it on my teeth. Well, fast forward a couple more years, and I start having a bad toothache. I go to a dentist (totally different place!) and I'm informed that tooth has a big hole in the back of it (where the filling material had obviously fallen out) and the tooth isn't even salvageable anymore!

I look at all of this and have to wonder if I would have been better off if I had only opted to have the bare minimum work done in the beginning? Seems like all these dentists did was create more problems for other dentists to correct, at my expense!

And my daughter is further making me question some of these dentists.... When she was 8 years old, the pediatric dentist commented that "he saw something on the x-rays that concerned him" and "she might need some dental work, but we'll see". The next time she came in for a checkup, he wanted to schedule an expensive dental surgery procedure for her because he claimed a tooth wasn't going to come in right, etc. etc. Well, I didn't have the money so I kept putting it off.... I did send her to the next scheduled checkup though, where they declared "She doesn't need that surgery after all!" (Really?! WTF?!)

Oh, and then there's my younger brother, who had all kinds of dental problems after his dentist screwed up a procedure -- but of course, denies any of it was his doing.