Careful with that radiation..Eugene

Careful with that radiation….

I know that I have said this before, but occasionally a paper comes along that really makes me think and this is one.  I came across this in the EJO advanced section of the website.  This study was carried out by a good team based in Leuven and they investigated the diagnostic utility of CBCT radiographs and essentially persuaded me to be careful of that radiation. It also allowed me to part name this blog on a very old Pink Floyd track that reminds me of my teenage years…Careful with that axe..Eugene

I have been using these for several years on a limited number of my patients and I have always been surprised at the quality of the images that are produced.  However, I remember the first time that we used a CBCT for a patient when a colleague of mine showed me a great image of a palatally placed canine resorbing a lateral incisor.  We were all impressed.  We then asked to see the DPT that had been taken as the “first line” radiograph. This showed extensive resorption of the lateral incisor!  We were just more confident in what we had seen.  This is the concept that has been investigated in this paper.

 Orthodontic treatment planning for impacted maxillary canines using conventional records versus 3D CBCT

Ali Alquerban et al

European Journal of Orthodontics Advance access publication 2014

Doi: 10.1093/ejo/cjt100

In this study they attempted to answer a simple question  “to compare orthodontic treatment plans in maxillary canine cases using conventional records and Cone Beam CT”.

They took 40 sets of records of patients who had two dimensional radiographs and CBCTs taken.   They were then viewed, along with study casts, by panel of experience orthodontists.   They recorded diagnostic information, planned the treatment and noted their level of confidence in their treatment decision.

 What did they find?

They found that the use of cone beam CT resulted in significant differences in the accuracy of diagnosis of canine position, canine development and detection of root resorption of lateral incisors.   At this point things look good for CBCT.

However when they evaluated the treatment decisions there were no differences in the planning decisions based on conventional views versus the CBCT dataset. Nevertheless, the level of their confidence in their decisions was higher with CBCT.

 So what does this mean?

They discuss the many implications of their findings in great detail in a lengthy discussion section. I will not go into all of this. However my interpretation is that the new technology helps us visualize problems well.  In other words, it can increase our perception and we feel more confident in our decisions

However, when we consider our judgements we can still produce clinical decisions using less sophisticated methods. This may be because the orthodontists who took part in the study were very experienced and they probably used a combination of their clinical experience from viewing conventional radiographs. I’m not so sure that this would be the case less experienced operators. There is a danger that less experienced orthodontists may prefer to use CBCT views.

This does bring me to considering radiation dose. ALARA and Sedentext EU guidelines state that CBCT should only be used in selected cases in which conventional radiographs cannot provide sufficient information. We should always bear in mind the harmful effects of radiation and remember this dose is accumulative

They also point out that there is a long term risk in radiation induced carcinogenesis and this risk may increase younger patients.

Will this paper influence practice?

I certainly hope so, and I will aim to reduce my use of CBCT to only those patients who I feel would benefit from more diagnostic accuracy.  At present, the risks are still too high when we can use conventional methods with equal effectiveness.