Careful with that radiation, Eugene.
When should we expose our orthodontic patients to radiation? This post is my personal view on this controversial area. You may or may not agree with me?
Long-term readers of this blog may be familiar with this title. I first posted about studies on CBCT in 2014 and used this title based on the Pink Floyd song. In these posts, I discussed studies that suggested we must be careful using CBCT imaging. I ignited this controversy again when I commented on the routine use of post-treatment CBCT in a recently reviewed paper. As a result, I felt I should discuss this subject in this new post. I know that my views will not be universally accepted!
An excellent place to start is to consider guidelines produced by experts in the field. One of the most extensive is the SEDENTEXCT project. This European project aimed to develop evidence-based guidelines for using CBCT in dentistry. This was published in May 2012. These were also incorporated into the British Orthodontic Society radiographic guidelines. Unfortunately, I could not find guidelines from the American Association of Orthodontists. As a result, I will first highlight some of the main messages from the SEDENTEXCT and BOS guidelines.
- No exposure to X-ray radiation is completely clear of risk. All ionising radiation has the potential to cause harm.
- Orthodontic radiographs irradiate children, so the need for judicious use is paramount.
- Rarely a portion of a chromosome may be damaged and mutated. This may lead to a tumour. There is no threshold below which these effects will not occur.
- These are stochastic events where the magnitude of the risk, though not the severity of the effect, is proportional to the radiation dose. This makes the distinction between safe and dangerous exposure to radiation impossible.
- As a result, the justification for radiation exposure is that we do more good than harm. Therefore, radiation doses should be kept low, and all exposures should be minimised and in the patients, best interest.
- CBCT is not recommended as a standard method of diagnosis and treatment planning in orthodontics.
- There is no justification for taking radiographs before a clinical examination.
- It is unethical to take radiographs for medico-legal, administrative or “just in case” if there is no clinical need.
So, what do we do now?
Firstly, we need to consider that, as these are guidelines, following them is not mandatory. Nevertheless, guidelines should be carefully considered. Importantly, we must have good reasons if our practice does not comply with guidelines.
I approached this discussion from the viewpoint of what I would like for me, my family, my children, and my children’s children. The bottom line is that no radiation exposure is entirely free of risk. I then considered the probability of harm, and the answer is that we do not know. As a result, I agree with the recommendations.
Finally, before I became an orthodontist, I was in a dental radiography post. The head of our department often stated, “Never take a radiograph if it is not going to change your clinical decision.” This simple statement provides a great simple message about dental radiographs.
We now need to think about how this influences our clinical practice.
Firstly, we should only take pre-treatment radiographs if they will be helpful and the benefits to our patients outweigh the risks. Will the information change our clinical decision?
Secondly, it is tough to propose one good reason for taking post-treatment radiographs. This is because post-treatment radiographs are of no benefit to our patients.
I know that many practitioners will disagree with these conclusions. However, I am not sure of the reasons for this disagreement. I often see arguments that the radiation dose is the same as a plane trip. However, the plane journey is a choice and provides a means of getting somewhere or going on a vacation.
Other points put forward are that CBCT views are low dose and perhaps comparable to a cephalogram and panoral view. However, they are not “no dose,” and we must remember this simple fact.
Another argument is that we need radiographs to provide information that may be useful in unplanned retrospective future research. This is simply nonsense. We should only take additional radiographs as part of a planned prospective investigation when we can consent the patient to have the investigation.
I think that have written enough to have a really good discussion in the comments section of this post.
Emeritus Professor of Orthodontics, University of Manchester, UK.