Maybe you’ve heard the phrase “cognitive dissonance” – the discomfort you feel when aware you have conflicting beliefs, thoughts or feelings. The phrase was coined by social psychologist Leon Festinger, whose classic study of a doomsday cult found that when our beliefs are challenged, we may actually double down and believe harder: When the world didn’t end as alien communications had told the cult members it would, they preached more loudly and publicly than ever.
For a while.
You can probably think of people who seem to get more confident and passionate about their beliefs when their ideas are questioned. There are plenty of examples in dentistry, such as the strange and persistent faith in things like mercury amalgam, fluoride and perhaps the demonstrated link between routine dental x-ray exposure and cancer.
Nearly a year after the findings were published in the scientific journal Cancer, complaints from mainstream quarters continue – as in three letters recently published in that same journal. Some, of course, are valid. The study, as we noted in our previous post, was not perfect. The reliance on self-reporting decades-old memories raises issues of reliability. The researchers acknowledged it themselves, noting that access to and analysis of dental records in a large epidemiological study like this one is simply cost prohibitive and too time consuming.
Other objections to the study, however, give some pause. For instance, one letter, as reported by Dr. Bicuspid,
co-authored by Stuart White, DDS, PhD; Charles Hildebolt, DDS, PhD; and Alan G. Lurie, DDS, PhD – all oral and maxillofacial radiologists – takes issue with the fact that the study focused on radiation exposure from bitewing and panoramic radiographs but not full-mouth radiographs, which deliver much higher doses to the brain.
In fact, full-mouth x-rays were taken into account. The cancer correlation was found only with frequent bitewings and panorex films. Similar risk was “observed for full-mouth series, among individuals who received yearly or more frequent scans at a young age,” wrote the researchers. “Risk estimates…were consistently in the same direction as for the other 2 film types.” They were not, however, statistically significant.
Another letter writer complains that no relation was drawn between dental x-rays and tumor location, the presumption being that if x-rays are the problem, we’d see a one-to-one correspondence here. But dental radiation (especially with older units) is not absolutely focused, nor are the effects of radiation entirely local. Rather, like oral foci (e.g., root canal teeth, cavitations), their local action can trigger a cascade of effects throughout the body, especially as it affects the function of the biological terrain. Focusing on the local is one of the surest ways of missing things happening elsewhere in the body – which is, perhaps, one reason why so many can keep thinking of amalgam as perfectly safe. So focused on the tooth, they forget the body that’s attached.
(And so focused on tumors, we might add, they seem to overlook research published around the same time which showed that dental radiation can induce DNA damage and cytotoxicity in oral mucosa cells.)
So why do the objections continue so long after this study was published? Many of the letter writers invoke fear of “suboptimal diagnosis,” but let’s think about this for a moment. Does your physician order x-rays every time you come in, whether or not you have symptoms or visible signs of internal illness or elevated risk for any particular health problem, just to make sure they’re not missing anything?
Why, then, should your dentist?
No, it makes more sense to take x-rays only when needed: a full-mouth series before treatment begins and then as conditions warrant. In our office, Dr. Glaros calls for x-rays only when needed to help with diagnosis and treatment. They are always digital (which reduces radiation exposure by up to 90% compared with traditional film) and never “routine.”
And when you consider the better quality, convenience and environmental friendliness of digital x-rays, why would you even want to stick with the old way of doing things?
Until the old film practices are finally no more, though, there remain two things a wise dental patient should do when it comes to imaging:
- Request and accept only digital x-rays (both individual radiographs and panoramic)
- Have a good relationship with your dentist and staff who welcome open discussion about such issues
Image by viscousplatypus, via Flickr