Some orthodontists may be exposing young patients to unnecessary radiation when they order 3D imaging for simple orthodontic cases before considering traditional 2D imaging, suggests a paper in Dentomaxillofacial Radiology (February 2011, Vol. 40:2, pp. 115-122).
There is ongoing debate in the orthodontic community over if and when to use cone-beam CT for orthodontic diagnosis and treatment planning, said Sunil Kapila, BDS, PhD, lead author of the paper and chair of the department of orthodontics and pediatric dentistry at the University of Michigan School of Dentistry.
While only a small number of orthodontists utilize the 3D imaging on a routine basis when developing a treatment plan, there are concerns of unnecessary radiation exposure. In contrast, the evidence summarized in Dr. Kapila's paper suggests that 2D imaging would suffice in most routine orthodontic cases.
The amount of radiation produced by cone-beam CT imaging varies substantially depending on the machine used and the field-of-view exposed, and some clinicians may not realize how much higher that radiation is compared to conventional radiographs, Dr. Kapila and colleagues noted in a press release.
One cone-beam CT image can emit 87 to 200 microsieverts (ÎĽSv) or more compared, to 4 to 40 ÎĽSv for an entire series of 2D X-rays required for orthodontic diagnosis, Dr. Kapila said. Considering that the average U.S. population is exposed to approximately 8 ÎĽSv of background radiation a day, 200 ÎĽSv equates to about 25 days worth of cosmic and terrestrial radiation.
"Most of the patients who need orthodontic treatment are young adults and pediatric patients," said Erika Benavides, DDS, PhD, a clinical assistant professor in the University of Michigan's department of periodontics and oral medicine. Dr. Benavides is the board-certified oral and maxillofacial radiologist who reads the cone-beam CT scans taken at the dental school.
"Keeping in mind that the radiation received has cumulative effects, adding unnecessary radiation exposure to the patient may result in higher biological risks, particularly in the more susceptible young children," she said. "This is why selecting the patients that would benefit the most from this additional exposure needs to be done on a case-by-case basis."
When used judiciously, cone-beam CT is an invaluable tool with a definite place in orthodontic treatment planning, Dr. Kapila and Dr. Benavides said. They advocate a balanced approach to utilizing cone-beam CT in orthodontic patients, Dr. Kapila said.
He and his co-authors reviewed the existing research on cone-beam CT and found that it is typically recommended in cases that include those with impacted teeth, temporomandibular joint disease, craniofacial abnormalities, and jaw deformities. While other patients could also benefit from 3D imaging, the decision to scan these patients should be made on a case-by-case basis after a clinical exam and evaluation of the specific patient needs, particularly when 2D imaging has shown that additional 3D information would result in a demonstrable benefit that would likely alter the treatment plan.
"There is nothing published on current usage patterns," Dr. Kapila said. "Most of the information is anecdotal. Some clinicians and orthodontists are using this technology routinely, but I believe that most of those that use 3D imaging use it fairly judiciously."
Copyright © 2011 DrBicuspid.com
