There may be an increased risk of developing thyroid cancer in people who have undergone repeated dental X-rays, new research has revealed.
The more dental X-rays a person has had, the greater their risk of developing cancer, a collaborative study by scientists from Cambridge, Brighton and Kuwait suggested.
And there needs to be further investigation into the commonly-held theory that low-dose radiation exposure through dental radiography is absolutely safe.
Only when a patient has a specific clinical need should a dental X-ray be prescribed, and not as part of a routine check-up, their study concluded.
The thyroid gland - situated in the neck - is known to be sensitive to ionising radiation, particularly in children, and dental radiography is often overlooked as a potential hazard to the gland, the team said.
About 1,900 new cases of thyroid cancer are diagnosed each year in Britain and the incidence rates more than doubled between 1975 and 2006.
Researchers, led by Dr Anjum Memon, of the Brighton and Sussex Medical School, said the increasing use of sensitive diagnostic techniques is not believed to account entirely for the rise and that other causes warrant investigation.
The research team, whose findings have been published in Acta Oncologica, called for further studies using dental X-ray records.
"If you asked 500 hayfever sufferers in the UK the same question you could make a similar link because around 26 million dental x-rays a year are taken. It has been 40 years since anyone thought dental x-rays were absolutely safe. Only patients in the highest risk groups of dental caries get x-rayed at 6 to 12 month intervals. The whole ethos of the Ionising Radiations Medical Exposures Regulations is clinical justification and every dentist attends refreshers courses every five years so these 'researchers' are not saying anything different. All these articles based on a poor research model will do is frighten people into refusing dental x-rays leading to missed diagnosis and worsening the state of dental hygiene. I am not a dentist defending the profession but a former member of the executive of the British Radiation Protection Association" - Tim Reynolds, West Midlands