An X-ray technique known as Cone Beam Computed Tomography (CBCT) has become increasingly common for dental use because it can provide more diagnostically important information than conventional X-ray examinations. But it is not without its issues, says a Malmö University researcher.

A disadvantage of CBCT is that it produces higher radiation doses, however, new research shows that in some cases the radiation dose can be reduced by as much as 80 per cent and still give satisfactory results.

For the average person, an X-ray examination is not a risk in itself. But we never take any images unnecessarily.

Kristina Hellén-Halme

When a problematic wisdom tooth needs to be operated on, the dentist needs to know exactly where the large adjacent nerve canal is, and when someone has had a bicycle accident and damaged their jaw, for example, the surgeon needs to know exactly what the injury looks like. In such cases, a referral is sent for imaging with CBCT.

“With the CBCT, we take pictures of the mouth and jaw from three angles — from the front, from below, and from the side; this is in order to be able to answer the question that comes with the referral,” says Kristina Hellén-Halme, associate professor and senior dentist in odontological radiology at Malmö University.

The odontological radiologists who work with this type of X-ray follow rules and regulations established by a Swedish authority. These regulations are there to ensure that people are exposed to as little X-ray radiation as possible during their lifetime. Previous research has shown that CBCT produces higher radiation doses than general X-rays used by dentists. If the CBCT is to be used, there must be a justification that it is required.

“For the average person, an X-ray examination is not a risk in itself. But we never take any images unnecessarily,” says Hellén-Halme.

Children and adolescents with joint disease in the jaw are often subjected to many X-rays. For this group of patients, it is very important to lower the radiation dose as they have a long lifespan ahead of them and risk being exposed to a high total radiation dose throughout life.

Hellén-Halme has supervised doctoral student Durer Iskanderani, who in her dissertation researched reducing the CBCT radiation dose by as much as 80 per cent. In the study, 34 patients underwent an extra X-ray examination with only 20 per cent of the regular radiation dose.

Four specialists in odontological radiology evaluated the images to see if the low dose images showed equivalent results as the images with a 100 per cent radiation dose or full prescribed dose. The study indicated that diagnostically comparable results can be achieved with one-fifth of the radiation dose.

The low dose has already been implemented at the faculty, where patients are received, this means that now five CBCT examinations can be performed before the radiation dose has been reached that previously corresponded to a single examination.

Text: Hanna Svederborn & Adrian Grist