Thyroid Cancer Risk May Increase Due to Multiple Dental X-Rays

X-ray of a head, prominently showing the teeth
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According to a number of research studies, your risk of thyroid cancer increases if you have multiple exposures to dental x-rays.

Your thyroid gland is very sensitive to radiation, and radiation exposure is a known cause of thyroid cancer. Exposure to ionizing radiation, especially at a young age, is a proven and well-known risk factor for thyroid cancer. The primary source of exposure to this type of radiation in the United States is x-rays done for medical diagnosis, including dental x-rays

But dental x-rays have long been overlooked as a source of that radiation exposure, given the generally lower dose of radiation used.

Repeated exposure, however, appears to be correlated to an increased risk of thyroid cancer, and according to researchers, their findings correlate to previous research that has found an increased risk of thyroid cancer in dentists, dental assistants, and x-ray workers.

Findings

Researchers have learned that study subjects who had up to four dental X-rays had more than double the risk of developing thyroid cancer than those who had never had a dental x-ray as part of their dental care. Those who had between five and nine X-rays had a risk more than four times the normal rate. And the greatest risk was for those who had received ten or more X-rays. In those patients, the risk was more than five times that of someone who had not received dental x-rays.

The implications of the findings are especially important, given the increased rate of thyroid cancer in the past several decades.

In the United States,  for example, thyroid cancer is the fastest growing form of cancer, and in the United Kingdom, the thyroid cancer rate has doubled in recent years. 

Interestingly, the risk of papillary cancer is the greatest from dental x-rays. No other medical testing/x-ray radiation exposures are linked to an increased risk of thyroid cancer.

 

A Word from Verywell 

Given this information, what should you do to help protect yourself and your family against an increased risk of developing thyroid cancer?

According to one study author, Dr. Anjum Memon, writing in the journal Acta Oncologica:

Our study highlights the concern that, like chest or other upper body X-rays, dental X-rays should be prescribed when the patient has a specific clinical need, and not as part of routine check-up or when registering with a dentist. So, one of the first things you can do is to make sure that you get dental x-rays only when your dentist has a specific need for them, and not just as a routine part of treatment, i.e., routine annual x-rays, or a routine dental x-ray with every checkup.

Another way to protect yourself is to ask your dental care professionals to protect you with a lead thyroid collar when doing any dental x-rays. The American Dental Association currently recommends shielding of the thyroid during dental x-ray examinations.The American Thyroid Association has also issued comprehensive recommendations regarding shielding during dental x-rays

Despite these recommendations, some dentist do not have thyroid collars, or lead aprons that have a neck shield.

In that case, you can use a collarless lead apron they have on hand for pregnant patients, to shield your neck area. This is not an optimal solution. Better to insist that your dental health practitioner get a suitable lead collar to protect the thyroid during dental x-rays. 

If you have young children, it's especially important to minimize their exposure to any unnecessary dental x-rays, and insist that their dentists and orthodontists also use a thyroid collar. Orthodontia in particularly can be a source of numerous dental x-rays, so pay particular attention to the number of x-rays orthodontists want to perform.

Children are especially susceptible to thyroid-damaging radiation, so you'll want to ensure they are not subjected to routine or excessive numbers of dental x-rays. And for children, any essential x-rays should only be conducted with the use of the appropriate lead thyroid collar.

Source: Memon, Anjum et. al. "Dental x-rays and the risk of thyroid cancer: A case-control study," Acta Oncologica, May 2010, Vol. 49, No. 4, Pages 447-453. Abstract/Summary.

Rajaraman, Neta  et. al. "A prospective study of medical diagnostic radiography and risk of thyroid cancer." Am J Epidemiol 2013;177:800-9. Epub March 15, 2013; doi: 10.1093/aje/kws315. https://www.thyroid.org/professionals/ata-publications/clinical-thyroidology/september-2013-volume-25-issue-9/clin-thyroidol-201325201-202/

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