Careful with that Ceph, Eugene (Part 2). Do you need that orthodontic cephalogram?
A discussion on the need for cephalograms
Over the past few days I have been in a heated debate on a General Dentistry forum about the lack of evidence underpinning one of the rapid orthodontic treatment systems that can be learnt from attending a two-day course at a hotel. As part of the debate the advocate of the short-term orthodontic system kept repeating a mantra that orthodontists take too many cephalograms. As a result, I thought that I would review the value of the cephalogram in this blog.
My first step was to quickly run a Pub Med search and this revealed several papers, some of which, I have reviewed previously on this blog. These are listed at the bottom of the page.
They all have a similar methodology in that the investigators enrol a group of experienced clinicians into a study that attempts to identify factors that influence their treatment decisions. In the first stage of these studies the orthodontists evaluate a set of records, for example, study casts and record their treatment decisions. After a period of time the exercise is repeated with the addition of cephalograms and the decisions are recorded again. They then calculated whether adding the cephalogram resulted in a change in the orthodontists’ decisions. All the studies report similar findings and show that the addition of a cephalogram did not result in a change in decisions. This is an important and clinically relevant finding.
This takes me back to a junior hospital posed (residency) that I did in my early career in Newcastle upon Tyne, UK in 1984. As part of this post I spent several clinical sessions a week in radiology. As a result I spent many happy hours reviewing radiographs in a dark room. My supervisor, Douglas Lovelock, continuously mentioned to me “do not take radiograph, unless it will change your treatment decision”. This influenced me, greatly, and I have never been a large-scale prescriber of cephalograms. This also made me interested in this type of research and I have followed it closely and published some papers in this area. It is now clear that there is a considerable amount of information suggesting that the cephalogram is not always necessary.
Do these studies provide useful information?
The simple answer to this is “yes they do” and we should be considering the need for cephalometric radiographs, in most cases. This is in many ways, reflected in the British Orthodontic Society guidelines on radiography.
However, when we interpret these papers we must also be careful to take into account the natural “noise” or variations between orthodontists when taking treatment decisions. This is because we are dealing with two types of variation that influences decisions. The first is perceptual variation; this is the variation in what a group of orthodontists see when they examine a malocclusion. The studies generally show that this variation is minimal. However, further variation arises from judgemental variation. This is when we make different treatment decisions because we make different judgements based on what we see. This arises from our interpretation of evidence or lack of evidence. Arguably, It could be suggested that the influence of the cephalogram is minimized by the judgemental variation.
The other issue that is frequently raised about this type of study is that they are “still life” and do not involve “real” patients. I’m not sure that this is a major problem, because most orthodontists are familiar with planning treatment using records away from the patient.
So what do we do now?
The evidence derived from these studies suggests that we do not always need a cephalogram. My interpretation of this is for me to consider my old mentors advice. When I examine a patient and I am certain that my treatment decision is the correct one, I do not take a cephalogram. However, if I am not certain on my plan, then I may need a cephalogram. As a result, I balance the potential risk of harm from the cephalogram against the risk of harm arising from an incorrect treatment decision.
It is certainly my impression that this is approach is common amongst many orthodontists and we are reducing the number of cephalograms that we take. There certainly is no case for the routine taking of cephalograms for all orthodontic patients.
Rischen RJ, Breuning KH, Bronkhorst EM, Kuijpers-Jagtman AM (2013) Records Needed for Orthodontic Diagnosis and Treatment Planning: A Systematic Review. PLoS ONE 8(11): e74186. doi:10.1371/journal.pone.0074186
Emeritus Professor of Orthodontics, University of Manchester, UK.