A University of Michigan (U-M) [removed]paper[/removed], published in the journal Dentomaxillofacial Radiology,suggests that some orthodontists may be exposing young patients tounnecessary radiation when they order 3D x-ray imaging for simpleorthodontic cases before considering traditional 2D imaging.

According to Sunil Kapila, BDS, MS, PhD (pictured), lead author of the paper andchair of the department of orthodontics and pediatric dentistry at theU-M School of Dentistry, there is ongoing debate in the orthodonticcommunity over if and when to use cone beam computed tomography (CBCT)for orthodontic diagnosis and treatment planning.

Kapila’s paper suggests that 2D imaging would suffice in most routineorthodontic cases. While Kapila concedes 3D images are better quality,the trade-off is higher radiation exposure for patients.

The amount of radiation produced by 3D CBCT imaging variessubstantially, depending on the machine used and the field of viewexposed. Some clinicians, however, may not realize how much higher thatradiation is compared to conventional radiographs. One CBCT image canemit 87 to 200 microsieverts or more, compared to 4 to 40 microsievertsfor an entire series of 2D x-rays required for orthodontic diagnosis,Kapila said. Considering that the average US population is exposed toapproximately 8 microsieverts of background radiation per day, 200microsieverts equates to about 25 days’ worth of cosmic and terrestrialradiation.

"Most of the patients who need orthodontic treatment are young adultsand pediatric patients," said Erika Benavides, DDS, PhD, clinicalassistant professor in the department of periodontics and oral medicineat U-M. "Keeping in mind that the radiation received has cumulativeeffects, adding unnecessary radiation exposure to the patient may resultin higher biological risks, particularly in the more susceptible youngchildren. This is why selecting the patients that would benefit the mostfrom this additional exposure needs to be done on a case-by-casebasis."

Both Kapila and Benavides said that, when used judiciously, CBCT is aninvaluable tool with a definite place in orthodontic treatment planning.

To that end, Kapila and colleagues reviewed existing data on CBCT andfound that this type of imaging is typically recommended in cases thatinclude those with impacted teeth, temporomandibular joint disease,craniofacial abnormalities, and jaw deformities. While other patientscould also benefit from 3D imaging, the decision to scan these patientsshould be made on a case-by-case basis after a clinical exam andevaluation of the specific patient needs.