A recent study released in April 2012 entitled "Dental X-Rays and Risk of Meningioma" has been well publicized in the media and has some patients concerned about the safety of dental x-rays. We have long known that high doses of radiation are linked with cancer and that radiation damage accumulates over our lifetime. For these reasons, guidelines and recommendations have been set to prevent overexposure to unnecessary radiation during exams. While this new study is valuable in that it reminds us to follow the established guidelines for x-rays to prevent diseases caused by radiation, experts are saying that the study is flawed and may greatly exagerate the risk. Read this from the American Dental Association! http://www.ada.org/news/6979.aspx
It is worth mentioning that scientific studies are important to the advancement of our knowledge, because it helps us link causes and effects to help us understand how to prevent disease. However, placing too much weight on a singular study leads to errors. A study must be duplicated and approached from different angles to eliminate previous errors, and if they come to the same conclusions, then the conclusions can be accepted as valid.
Another reason to take singular studies with a grain of salt is the fact that there are many entities that are paying to have studies done to prove something that is in their own self-interest, which may not be correct. A big problem is that when a particular study is presented in the media, the public often take the results as fact, only to have the study proved to be in error later on.
(Here is an example of a study that caused a lot of alarm only to be found in error): http://www.cnn.com/2011/HEALTH/01/06/autism.vaccines/index.html
Two large errors stand out about this particular study. The first is that the study's conclusions are based largely on memory recall of patients about the frequency that they had dental x-rays through their lifetime. From my experience, patients (and doctors) are very innacurate in remembering what has been done in the dental office. (That is why clinical notes that are written at the time of the visit are so valuable.) Often there is a huge divergence between what someone remembers and what actually happened.
"The study has some drawbacks that make the link between dental x-rays and meningiomas far from certain. Perhaps most importantly, it relied on participants’ memories about their history of dental x-rays (rather than on dental records themselves). Such studies are subject to a phenomenon that scientists call “recall bias,” when people with a disease may be more likely to look for a cause. This might have caused the meningioma patients in the Cancer study to over-report the number of dental x-rays they received, which could have contributed to the findings. Because of this, the study results can only be considered suggestive of a possible link, and more rigorous studies would be needed to prove it." http://www.cancer.org/Cancer/news/News/study-examines-possible-link-between-dental-x-rays-and-meningioma-risk
"Can you remember how many dental x-rays you received over even the last five years? I doubt you can. I doubt I can, and I’m a dentist. I asked several of my patients, including a physician, and not one of my patients could accurately remember the amount of x-rays they had at my office over the last five years. One thing that was consistent was that every patient I asked overestimated the actual amount of x-rays they had received." http://www.phillyburbs.com/lifestyle/your_health/new-study-on-dental-x-ray-brain-tumor-risk-not/article_2a29823e-8d49-11e1-9767-001a4bcf6878.html?photo=0
An interesting follow-up to this study would be to test patient's recall of their x-ray history and compare it to the actual dental records!
Secondly, (and the author's mention this in their study), radiation from dental x-rays has decreased dramatically in the last 50 years. Modern technology has reduced radiation exposure up to 80% of what it once was. Now, radiation exposure from dental x-rays is rather insignificant when compared to medical x-rays and even background radiation, so even if the subjects of the study had a perfect recall of how often dental x-rays taken over 50 years, the risk for dental x-rays causing brain cancer is now significantly lower than was found in this unscientific study.