Can Dental X-Rays Cause Thyroid Cancer?

X-rays represent a type of ionizing radiation, which in turn can cause damage to one’s cells and increase the risk of developing cancer.  While the focus of this blog post will be on dental x-rays, it’s important to understand that all x-rays emit ionizing radiation.  However, there are a few reasons why I’m specifically focusing on dental x-rays.  First of all, because of the proximity of the teeth to the neck, the thyroid gland has a greater chance of exposure when compared to other types of x-rays.  In addition, many people get annual dental x-rays, and so one of the main goals is to discuss the risks vs. benefits, and to try to determine if the benefits of getting annual dental x-rays outweigh the potential risks.

Let’s begin by trying to answer the following question…”why do many dentists recommend annual dental x-rays?”  There is no question that one’s oral health is important, and the main reason why many dentists recommend frequent x-rays is to detect the early formation of dental cavities.  This of course doesn’t happen overnight, as what usually will happen is that plaque will accumulate on the tooth, and bacteria will produce acid that will slowly demineralize the tooth.  This of course is why it’s important to brush your teeth on a regular basis, as this helps with the prevention of plaque buildup.  However, if someone doesn’t brush on a regular basis and/or they eat a lot of sugar, then this buildup of plaque can lead to a dental cavity, which can be spotted on a dental x-ray.

Obviously the goal should be to do what you can to prevent dental cavities from forming, but when they do form, what happens if you don’t get this addressed?  Well, if this isn’t treated then the cavity will usually become larger, and probably will affect the inner layers of the tooth, called the dentin and pulp.  Eventually the damage can be severe enough where the only solution is to get a root canal or a tooth extraction, and there are risks of both of these.

So in no way am I suggesting not to get dental cavities filled, although you of course want to make sure you don’t get any mercury amalgams.  However, is it necessary to get annual dental x-rays to detect the early formation of these cavities?  In my opinion most people don’t need to get dental x-rays every single year.  This is especially true for those people who practice good dental hygiene, as in most cases a cavity will take at least a few years to advance to the point where it causes severe damage to the dentin and the pulp of the tooth.  I’m sure there are exceptions to this, and of course if you are experiencing pain or a sensitivity in your teeth then it probably is a good idea to get a dental x-ray, even if the last one you had was recent.

How Often Should You Get Dental X-Rays?

Once again, keep in mind that it is only my opinion that most people don’t need to get annual dental x-rays.  And while many other natural healthcare professionals share the same opinion, of course most conventional dentists don’t feel this way.  You might be wondering how frequently I would recommend for people to get dental x-rays?  Should they wait until they experience pain or a sensitivity?  I probably wouldn’t take this approach, and I’d say getting dental x-rays every two or three years probably is fine for most people. ..assuming you are brushing your teeth at least twice per day and flossing at least once per day.  I’m sure there are some reading this who feel that every two or three years is too frequent.  Over the last few decades the longest I have gone between getting dental x-rays has been four years, and in this situation the x-rays revealed no cavities or other issues.  And I’m sure some reading this have gone even longer between having regular dental x-rays without having cavities or other oral problems.  If this is the case then please feel free to share your experience in the comments section below.

How Does Ionizing Radiation Cause Cancer?

Of course it’s not just dental x-rays that increases one’s risk of developing cancer, as all x-rays, as well as other types of procedures involving ionizing radiation, can increase your risk of developing cancer.  Just as a reminder, I’m focusing on dental x-rays because of the proximity of the teeth to the thyroid gland, and also because many people get annual dental x-rays without thinking twice.  As for how ionizing radiation causes cancer, what happens is that ionizing radiation causes oxidative stress and leads to the formation of free radicals (1) (2) (3).  Free radicals are molecules that are highly unstable, and they play a key role in the initiation and progression of tumor cells (4) (5).

But why do some people who are exposed to radiation develop cancer, while others don’t?  Well, there are a few factors that can play a role.  Genetics does seem to be one factor.  But epigenetics is usually a greater factor, and what this means is that one’s external environmental is what affects the genetics.  In other words, someone might have a genetic susceptibility to a certain type of cancer, but eating a poor diet and/or other factors will be primarily responsible for the development of cancer.  Sometimes it’s hard to make this connection, as a few years ago I worked with a patient who developed breast cancer, even though she lived a healthy vegetarian lifestyle, exercised regularly, etc.  On the other hand, many people eat plenty of junk food and don’t develop cancer.  Similarly, some people receive a lot of x-rays and don’t develop cancer, while others who develop cancer don’t have a history of frequent exposure to ionizing radiation.

Some Facts About Thyroid Cancer                                       

Thyroid cancer is the most common malignancy of the endocrine system, representing 3.8% of all new cancer cases in the United States and is the ninth most common cancer overall (6).  The American Cancer Society estimates that 62,450 people in the United States will be diagnosed with thyroid cancer in 2015, and 1,950 deaths will result from the disease (6).  95% of the cancers being of follicular cell origin-papillary, follicular, or anaplastic thyroid carcinomas (7).  Both papillary and follicular thyroid cancers have good survival rates, with the 5-year survival rate approaching 97%, although the median survival for a patient with anaplastic thyroid carcinoma is measured in months (7).  There is evidence of an increased risk of developing thyroid cancer in those with Hashimoto’s Thyroiditis and Graves’ Disease (8) (9) (10) (11).

But why do some people develop thyroid cancer?  Well, like most other cancers it seems to be due to a combination of genetic and environmental factors.  Of course the focus of this blog post is on the risks of dental x-rays, and below I’ll mention some of the research studies which show a correlation between the ionizing radiation in dental x-rays and the development of thyroid cancer.  But there can be other factors as well.  Thyroid cancer is more common in women, especially between puberty and menopause, and therefore estrogen seems to play a role in its development (12) (13) (14).  So doing things to improve one’s estrogen metabolism can also help to prevent thyroid cancer from developing.

What Does The Research Show Regarding Dental X-Rays and Thyroid Cancer?

So what does the research show?  First of all, an increased risk of thyroid cancer has been reported in dentists, dental assistants, and x-ray workers (15).  One case-control study provided some evidence that multiple exposure to dental x-rays may be associated with an increased risk of thyroid cancer (15).  Another study looked at different types of diagnostic x-rays, and found that overall there was no clear evidence of thyroid cancer risk associated with diagnostic x-rays except for dental x-rays (16).  And there are some other studies which show an increased risk of thyroid cancer with regular dental x-rays (17).

I’m sure many dentists will be angry upon reading this information, and keep in mind that I’m not suggesting that most people who receive dental x-rays on an annual basis will develop thyroid cancer.  And to be fair, there are other factors which also can increase someone’s susceptibility.  For example, since nutrients such as selenium might help to prevent thyroid cancer (18) (19), eating a poor diet can potentially increase one’s risk of developing this condition.  And there are many other minerals and phytonutrients which can help to prevent cancer.  Earlier I also mentioned how problems with estrogen metabolism can be a factor in the development of thyroid cancer.   In addition, wearing a thyroid shield while getting dental x-rays will decrease the risk of getting thyroid cancer (19), and so if you do get dental x-rays I would make sure to ask for a thyroid shield.

5 Takeaways From This Blog Post                                                                                   

Takeaway #1: Think twice about getting annual dental x-rays.  Once again, this is just my opinion, and I know some people reading this will disagree with me.  But while there are benefits of receiving dental x-rays, I don’t think most people need to receive them every single year.

Takeaway #2: When you get dental x-rays, make sure you wear a thyroid shield.  As ridiculous as this may sound, not all dental offices will provide their patients with a thyroid shield prior to having x-rays taken.  In fact, in the past I have had to ask the technician for a thyroid shield.

Takeaway #3: Maintain good oral health.  If you minimize your consumption of sugar, and brush and floss regularly, then this will greatly decrease your risk of having problems with your teeth and gums.  And of course this in turn will reduce your chances of getting dental cavities, which in turn will allow most people to get away with having less dental x-rays.  Keep in mind that I’m not suggesting that you don’t go to the dentist for regular cleanings, as I do think this is a good idea.

Takeaway #4: Eat a healthy diet.  While it’s important to minimize your consumption of sugar, you also want to eat plenty of whole healthy foods in order to make sure you get the necessary nutrients to help prevent cancer.  Eating plenty of vegetables, along with some fruits, can provide you with a lot of the nutrients and phytonutrients you need in order to help reduce one’s risk of developing cancer.

Takeaway #5: Do things to improve estrogen metabolism.  Since  increased estrogen levels can increase the risk of developing thyroid cancer (as well as some other types of cancers), it makes sense to do things to improve estrogen metabolism.  In the near future I will be releasing an article which focuses on improving estrogen metabolism.

In summary, x-rays are a type of ionizing radiation, which is one factor in the development of certain types of cancers.  As a result, it is a good idea to minimize one’s exposure to ionizing radiation.  Many dental offices recommend for their patients to get annual dental x-rays, and the research shows an increased risk of thyroid cancer with dental x-rays.  This doesn’t mean that people should never get dental x-rays, and I do think it’s a good idea to get regular cleanings.  But perhaps it’s time to question whether it’s a good idea to get annual dental x-rays.  Just like anything else, one needs to weigh the risks vs. benefits, and I’m not convinced that the benefits of annual dental x-rays outweigh the potential risks.

Please feel free to share your thoughts about getting annual dental x-rays in the comments section below.