People who received frequent dental x-rays as children could be at increased risk of developing a commonly diagnosed primary brain tumour, according to a study of almost 2,800 people.
The study, published in the journal Cancer, shows that adults diagnosed with meningioma who reported having a yearly bitewing exam, which uses an x-ray film held in place by a tab between the teeth, were 1.4 times to 1.9 times as likely as a healthy group to have developed such tumours.
Dental x-rays are a common artificial source of exposure to radiation, an environmental risk factor for developing meningioma.
To examine the link between dental x-rays and the risk of developing meningioma, Elizabeth Claus, from the Yale University School of Medicine, and her colleagues studied information from 1,433 patients who were diagnosed with the disease between the ages of ages 20 and 79. The team also studied information from a control group of 1,350 people who had similar characteristics but who had not been diagnosed with a meningioma.
Over a lifetime, patients with meningioma were more than twice as likely to have had a bitewing exam, which uses an x-ray film held in place by a tab between the teeth.
An increased risk of meningioma was also linked with panorex exams when taken at a young age or on a yearly or more frequent basis. Panorex exams are taken outside of the mouth and show all of the teeth on one film. Participants who reported receiving these exams when they were younger than 10 years old were almost five times more likely to have developed meningioma. Those who reported receiving them on a yearly or more frequent basis were up to three times as likely to have developed meningioma.
Dental patients today are exposed to lower radiation levels than they were in the past, but the research should prompt dentists and patients to re-examine when and why dental x-rays are given, Dr Claus said. “The study presents an ideal opportunity in public health to increase awareness regarding the optimal use of dental x-rays, which unlike many risk factors is modifiable.”
Matthew Hopcraft, Director of Clinical Education at the University of Melbourne Dental School, said it would not be common for the average patient to have radiographs more frequently than once per year.
“Frequency of bite wings radiographs would range between six months and three years, and is based upon a risk assessment of the patient balanced against patient safety [taking into account] radiation exposure,” Associate Professor Hopcraft said.
“Six-month frequency would be rare and would apply for a patient with high risk of tooth decay, where progression of a lesion is rapid, and early detection and prevention is essential. Most patients are likely to fit into the category of requiring bite wings every 12-to-36 months, with once every two years likely to be the norm.”
In recent years, changes to radiographic equipment had led to a reduction in the exposure received by patients undergoing an x-ray - sometimes by up to 90%, he said.
Malcolm Sperrin, Director Of Medical Physics at Royal Berkshire Hospital in Britain, said: “Ionising radiation from any source is known to have a potential health detriment although the very low radiation dose leads to an overall risk that is extremely small.
"That being said, this paper does provide sensible statistical evidence for a correlation between dental radiation exposure and the incidence of meningioma. However, caution is needed in interpreting the conclusions since there is no data that summarises the radiation exposure to the patients.
"The paper does state that the findings relate to older, higher exposures and the overall intention is to raise awareness of risk factors which is commendable.”