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Dental Xrays and Changing Science

Coronavirus has led to an amplification of questioning and mistrusting the medical science and experts regarding lock downs, masks, vaccines and more. Starting with no knowledge or history of Covid 19 – scientists continually had to make the best decisions based on the data they had at the time. As more cases and thus data was available, the public trust should have grown. Unfortunately, the opposite happened as people viewed changing recommendations as meaning they were misled somehow with the initial guidelines.


After that intro I hope you’re asking what that introduction has to do with dental x rays. A lot, but on a much slower and longer time frame than our extreme example of Covid-19 in the past 6 months. Over my twenty-year career I’ve seen the same sort of challenges with changing recommendations leading to questioning and mistrust by dental patients regarding dental x rays. The remainder of this article will be focused on the current state of dental x rays and the advances that have been made.


The first question to ask is why dentists take x rays and how many and how often should they be taken. Dental x rays are the only way we can evaluate what is going on inside teeth, between teeth, and the bone and supporting structures. Nearly half of all cavities are found on x rays that otherwise would be missed. Gum disease (periodontal disease) can only be accurately diagnosed by seeing the level of bone that supports teeth on x rays. Dental abscesses are also diagnosed by dental x rays. Without dental x-rays many serious dental issues would be missed.


There is no standard timeline as to how often dental x rays should be taken. The standard of care is for dentists to use As Low As Reasonably Achievable (ALARA) principle. Basically, it states the dentist should prescribe as low a numbe


r of x rays at as low of a dosage that will allow proper diagnosis. This is done by prescribing x rays based on the patients specific risk factors and also using the latest technology to decrease radiation exposure.


This leads to the second question of whether dental x rays are safe. The simple answer is yes, dental x rays are safe. The more nuanced answer is that there is no absolute safety and therefor we follow the ALARA principle to decrease any small risk there may be.

In order to explain safety, we need to quantify the radiation exposure. The measure used is millisieverts (mSv). The typical modern dental single x ray uses less than 0.005mSv, a dental panoramic x ray is 0.01mSv and a dental conebeam is 0.03mSv. To put these numbers in perspective to other medical imaging, a mammogram is 0.4mSv and a chest x ray is 0.1mSv. Many people don’t realize that we are constantly barraged with radiation in our daily lives. The average person receives 0.01 mSv per day from just living on earth. These numbers are on the high end as far as dental x rays, the fact is we have newer technology of digital x rays that allow the dosage to go even lower than stated above. To put this in perspective again, the maximum annual dose permitted in US radiation workers is 50mSv or 10,000 dental x rays.


Even though the amount of radiation dosage is considered extremely small and safe there is still a concern and mistrust among patients. In 2010, Dr. Oz made fear inducing claims on his TV show about dental x rays but failed to disclose that his fear inducing segment was based on radiation doses from 50-60 years ago and debunked article. This just shows how easy it is for people to cherry pick ideas and information and present them as facts that can scare people. Real science is based on studies that can be reproduced and reviewed by peers to ensure they were properly done. Over my twenty years I’ve continued to have patients refuse dental x rays out of fear. We attempt to educate the safety and minimal risks weighed against the larger risks of missed dental disease that can lead to significant problems.


The final area of mistrust we see in dental x rays are the lead aprons. Due to the low radiation doses and collimation (a device that narrows the beam and minimizes the exposure to a small specific area) the lead apron is no longer a needed item according to radiologists. The challenge is many states still have a requirement in state practice codes that haven’t been updated in decades. The second problem is that patients have been trained to expect lead aprons for 50 years and are skeptical when a perceived safety measure is no longer used. In fact, this is a problem in medical radiology as well. This past January, the Radiological Society of North America recommended lead aprons no longer be used in any medical imaging, even on pregnant patients. The science has advanced, and they have determined that there may be a higher risk with the apron on. They found that if there is any radiation that is scattered from the site being x-rayed, the apron can trap it and increase the dose to the body.


This is a topic that can get quite scientific and detailed, but I hope this simplified overview helps in understanding the safety and challenges to changing science and guidelines in a world of many so-called experts. If you have concerns still about dental x rays or lead aprons, I recommend you ask questions of your dentist. In fact, this topic was inspired by a question from a patient which I appreciated the person being willing to share their concern and have a conversation rather than make assumptions that lead to mistrust.


This blog post was written for the Capital Democrat Staying Healthy column for print September 17, 2020 by Dr. Joiner.

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