Recently I have been getting a lot of questions about a study released April 10, 2012 which reported that dental x-rays lead to an increased risk of a benign brain tumor called a meningioma. The results of this study got a lot of play on the news and in popular journals, and has understandably created some concern in a lot of people, including many of my patients. If you want to read the study for yourself, it can be accessed here: http://onlinelibrary.wiley.com/doi/10.1002/cncr.26625/full. Since so many people have asked me what my opinion is on this, I have decided to articulate it here. These are, of course, my opinions only, and others may arrive to different conclusions.
Before I discuss the study, I want to give full disclosure and state what my biases are. I have a very strong bias to do my job well. A big part of my job is to diagnose and treat problems of the mouth. Without x-rays, I cannot do this well. At least half of the pathology that I find in my patients’ mouths is found ONLY in dental x-rays. Without x-rays a diagnosis can be made too late. A small cavity that could be restored with a small filling, turns into a root canal and a crown or an extraction. An abcess that could be treated before it even becomes symptomatic, turns into an extremely painful infection that causes half of the face to swell up and can land the person in the hospital. A tumor in the bone that goes un-diagnosed until the treatment is extremely disfiguring, or even untreatable. I have seen all of these things happen on patients who have not had xrays taken when they should have. Since it’s my job to prevent these things from happening, I am leary of anything that will prevent me from doing so. With that said, I am very aware of the need to minimize risk from the radiation of the x-rays themselves, and do everything within my power to do so. I will address this later.
As for the study, I have a number of issues with it. Some of my issues have to do with the study itself, a lot has to do with how the media has sensationalized and misreported it.
First, I’ll address the study. My biggest complaint about the study is how they collected their data. To measure how much exposure to x-rays a person has had, they asked them how many x-rays of various types they had had in their lifetime separated into 4 different time frames. While the people doing the study acknowledge possible inaccuracies in this method, I believe it’s so inaccurate that it could negate the results completely. How many of those reading this can even come close to telling me how many x-rays they had from age 10 to 19 for instance, and of what type? With all of my new patients I always ask what recent x-rays they’ve had so that I can acquire the x-rays from their previous dentist. I then follow up by calling the previous dentist to have the x-rays sent to me. In the great majority of times the patient has had less x-rays, and they’re farther in the past, than they believe. And this is just recent x-rays. I can’t imagine how wildly inaccurate it would be to ask someone to recall what x-rays they had several decades previously.
In my opinion, the study also doesn’t stress enough the importance in how x-rays have changed for the better over the years. Many years ago you would get more exposure in a single x-ray than you would in about 40 today. How many of these self-reported x-rays where of this type, and how many were of each successive step in improving dental x-ray technology over the years, was not addressed. Even if they had accounted for this, to make people fear today’s technology by looking at the consequences of the technology of decades ago is irresponsible, in my opinion. The exposure of today’s digital x-rays is miniscule compared to the x-rays of the past.
I am also concerned that the study does not address other types of x-rays (chest x-rays for instance) or other environmental, life-style (smoking, alcohol), or dietary risk factors that may increase the risk for meningiomas. There are many known carcinogenic factors that I feel should have been included in the study before we can make the conclusion that it is the dental x-rays that are the problem.
Finally, there is a table in the study that casts suspicion on the results of the study as well. According to Table 2 of the study, the risk of someone getting a meningioma from bitewing x-rays is 50 to 100 times greater than it is from a full mouth series of x-rays. A full mouth series is about 20 x-rays. Bitewings are 2 to 4 x-rays. Why is there a far greater risk from taking less x-rays? It doesn’t add up.
The media has taken this report and run with it. They have reported the conclusion of the study without noting any of it’s methods, limitations, or flaws. They have reported the American Dental Association’s (ADA) views on it in a misleading or completely false manner. For instance, in a recent article in The Economist it states “... guidelines from the American Dental Association state that healthy adults should have a bitewing x-ray no more than once every two or three years...” This is partially true. The ADA’s recommendations can be found here: http://www.ada.org/sections/professionalResources/pdfs/topics_radiography_examinations.pdf. That recommendation is only for adults, and only if they don’t have any increased risk factors for decay. The ADA goes on to list 18 items that put people at greater risk, including poor oral hygiene (not flossing every day), previous history of decay, family history of a lot of decay, among many other factors. My experience is that it is a minority of people that fall into this category of low risk, though they do exist. For those that DO have any of the risk factors, the ADA recommends bitewing x-rays every 6 to 18 months. This, needless to say, was not mentioned in the article, or any of the news reports I saw.
Worse, in the same article it states that according to the ADA, “...there is little reason to x-ray patients who do not have symptoms.” This is just blatantly false. I could not find anywhere were the ADA has said this, and I can’t imagine them doing so. The majority of dental problems have NO symptoms until the pathology has progressed too far. Many times I have seen a tooth decayed off to the gumline, yet absolutely painless. I have seen infections in x-rays that were eating huge holes in the bone, but were totally pain free. To leave pathology undiagnosed just because there are no symptoms is unacceptable in my opinion. My goal as a dentist is to treat pathology BEFORE it becomes symptomatic. Doing this leads to a much greater chance of avoiding pain and infection, and a much greater chance of keeping healthy teeth for a lifetime. Without dental x-rays my ability to do this is severely hindered.
Recently I even saw a news report where the reporter was interviewing an “expert” regarding this study. The expert was a gynecologist. How a gynecologist became an expert on dental x-rays, I have no idea, but her view on them was skewed as well. The dental field has a relatively unique situation in that disease can be caught very early before any symptoms develop with x-rays that have very low radiation, and thus very low risk. Bringing a non-dental expert to report on a dental issue is fine for ratings, but not so good at informing the public on an issue that has very important health ramifications.
Despite all my problems with the study, and how the media sensationalized it, I have always done, and will continue to do, everything within my power to minimize all exposure my patients get from x-rays. We have used aprons with thyroid collars for decades. Our x-ray heads are very new and of the highesth quality. We only take digital x-rays, which need significantly less radiation than film. Even when we did use film, we used the fastest film available, requiring the least amount of radiation prior to the evolution of digital x-rays. We take into account many factors in recommending x-rays, and try to minimize how many and how frequently we take them.
Ultimately, the choice to have x-rays taken or not is yours. I only give recommendations. The study and the media spent a lot of time talking about risks involved with taking dental x-rays. In my view, the study did not prove these risks exist, but that’s not to say there are no risks. What the study and the media reports did not do is talk much about the risks of NOT taking dental x-rays. There are very real, proven risks of not taking dental x-rays. Since the media did such a poor job of explaining these risks, I want to make sure my patients understand them. I hope I have done a good job of starting that dialog here, but I would be happy to discuss this further in person, on the phone, or via email. My goal, as always, is to inform my patients of all their options to the best of my ability, and help them make the best decision for themselves. I understand completely when I have patients decline x-rays. I will always explain to them the risks of not taking the x-rays, but that’s not my way of trying to “convince” them - I just want my patients to make a fully informed decision.
For those who are concerned about this, I hope this helps, and once again I’m always available to discuss this further if there are any questions.