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Are dental X-rays safe?

TINKER AIR FORCE BASE, Okla. -- Dental radiographs, commonly referred to as X-rays, are pictures of the teeth, bone and surrounding soft tissues. Dental X-rays help dentists see cavities, pathology such as cancer in the jaw and bone loss that sometimes cannot be seen during a clinical exam.

Radiation of dental X-rays penetrates oral structures at different levels depending on their densities. The dosage of X-ray radiation is about 0.005 mSv, equivalent to a few days' worth of background environmental radiation exposure. Background radiation is a type of radiation constantly present in the natural environment of the earth, which is emitted by natural and artificial sources. Incidental exposure is further reduced by the use of lead shields, lead aprons, and lead thyroid collars. Radiology technicians' exposure can be reduced by stepping out of the room or stepping behind a lead barrier wall.

Over the years, dental radiology has advanced. Conventional radiographs exposed patients to more radiation. Digital X-rays, which replaces films with electric sensors, exposes patients to significantly less radiation and are processed much quicker than conventional radiographs.

In April of this year, a study suggested a possible link between dental X-rays with a particular benign tumor called meningioma. Two groups of people, more than 1,000 each, were studied. One group had been diagnosed with meningioma, and the other group was not diagnosed with the tumor. All were asked to recall their past dental X-ray history, but only a few of the participants' dental records were reviewed by the researchers.

According to the article, "people with a tumor or any other unwanted health outcome are far more likely to remember that they had X-rays, air pollution or pesticide exposure, cell phone use or anything else that might be suspected of causing the problem."

The article indicates that there is a higher risk of developing a tumor, such as meningioma, when exposed to panorex radiographs when compared to bitewing radiographs. The study's findings suggest those people in the study may have had a greater risk of developing meningioma due to frequent dental X-rays since childhood. However, the American Dental Association's guidelines for X-rays strongly encourage the ALARA (As Low As Reasonably Achievable) principle: when X-rays are necessary, exposing the patient to as little radiation as possible is key.

As a response to public concern and wide media coverage regarding the previous study, the ADA released an article titled, "Association with brain tumors based on patient recall of radiographs." According to the article, "studies have shown that the ability to recall information is often imperfect. Therefore, the results of studies that use this design can be unreliable because they are affected by what scientists call 'recall bias."

The article includes a statement by the American Academy of Oral and Maxillofacial Radiology questioning the validity of the study. As a final blow to the previous study, the ADA article argues the amount of radiation absorbed for dental exams has declined over recent years. Better imaging technology and other preventative methods have been implemented to further decrease the dose of radiation absorbed by the patient. Due to the weakness of the study this article was based on, there is no direct correlation between dental radiographs and tumors.

In the words of Dr. Elizabeth Claus, a neurological surgeon at Brigham and Women's Hospital in Boston and the Yale School of Public Health, as well as the leader of this study, "Don't stop going to the dentist."

For more information, call the 72nd Dental Clinic at 736-2000 or visit www.ada.org.