June 15, 2018
In the past lead aprons and thyroid shields were a standard for all dental x-rays, and for good reason. But with the adoption of digital radiographic imaging there is a significant reduction of harmful radiation. As a result, a lot of professionals believe the lead shield and thyroid covers are no longer necessary. The varied interpretation in dentistry and grey areas of regulation make guidelines for protection against radiation unclear. So here is some information to consider when making the decision on these regulations.
What is the thyroid gland?
The thyroid is a large, ductless gland at the base of the neck. It is approximately two inches long and lies below the prominence of cartilage called the Adam’s apple. This butterfly shaped organ has two sides called lobes that flank the windpipe. Sometimes the lobes are connected by an isthmus, or strip of thyroid tissue. Sometimes a person has two separate thyroid lobes.
How does the thyroid gland work?
This organ secrets hormones, specifically Triiodothyronine (T3) and Thyroxine (T4), to regulate growth and development by controlling metabolism, or the body’s use of energy. The hormones help regulate body functions like breathing, digestion, heart rate, central nervous system, menstrual cycles, body temperature, and more. If T3 and T4 levels are too high you might experience rapid heart rate, diarrhea, and weight loss. If T3 and T4 levels are too low you may have slower heart rate, constipation, and weight gain. T3 and T4 from the thyroid travel the bloodstream and reach almost every cell in the body, so you can see why protecting it from ionizing radiation and cancer is important.
Are dental x-rays dangerous?
Exposure to radiation, especially at a young age, is a well-established risk factor for cancer. Radiation is also accumulative, and every dose of radiation you receive sticks with you and adds to the accumulated amount. But intraoral radiography is a well-established diagnostic tool in dentistry. It is how practitioners make informed decisions about a patient’s oral health. Thus, it is important for each exposure to be justified to benefit the patient, and practitioners must do what they can to minimize radiation dose following the ALARA principle (as low as reasonably achievable). While the amount of harmful radiation is reduced with digital x-rays, radiation is still generated. This is why the American Thyroid Association (ATA) recommends reducing thyroidal radiation exposure as much as possible without compromising clinical goals of the dental examinations.
The importance of still using thyroid shield covers
The ATA released a publication in 2013 stating the thyroid as one of the most radiosensitive organs in the neck and head area and among the most susceptible sites for radiation-induced cancer. Thyroid conditions, as you read, can have serious health impacts for the entire body. In 2012 the American Dental Association (ADA) stressed the need for shielding the thyroid during dental x-rays whenever possible. This is for both children and adults, especially for exposures in the upper anterior region which places the thyroid gland within the primary beam of the x-rays. With no lack of clarity professionals need to abide these equipment guidelines in the safe capture of radiographs.
Read more about the different type of dental x-rays:
Bitewings - xrays in a closed biting position
OPG - full mouth x-ray, also called panoral or panorex