Cephalograms: Are we in need of some lateral thinking?
Lateral cephalometry has been pivotal in improving our knowledge of facial growth and response to treatment. For example, In the 1940s and 1950s, the use of cephalograms showed that we could not change skeletal growth with inter-arch elastics. This led us to conclude that the skeletal pattern is essentially ‘immutable’. Over the years, researchers have continued to trace cephalograms to understand the relative contribution of skeletal and dental change associated with various treatments. As such, the use of cephalometry as a research tool has been indispensable and even transformational.
Of course, daily, most of us also use cephalometric radiographs to assist with our diagnosis and treatment planning. But how useful are cephalograms in routine practice? Do they provide us with critical insight that influences our diagnoses and treatment plans? Or are they unnecessary in some, most or indeed all of our cases? A team from Farmington, Connecticut did this neat study to answer these questions. The Angle Orthodontist published the paper.
Authors: Anjali Dinesh; Sunil Mutalik; Jonathan Feldman; Aditya Tadinada
Angle Orthod. 2020. doi: 10.2319/062319-425.1
What did they do?
They did an analytic study to assess the effect of the inclusion (or omission) of a lateral cephalogram as part of baseline records on both orthodontic diagnosis and treatment planning decisions.
They selected 7 rates (3 orthodontists and 4 residents) The raters had between 1 and 10 years of orthodontic experience. Then they asked them to examine records from 100 orthodontic patients. They took this sample of patients from a private orthodontic office. It included patients ranging in age from 8 to 21 years with a range of malocclusion types.
They gave the raters the patients records. These were intra-oral and extra-oral photographs, digital models and a panoramic radiograph. They asked them to complete a 7-question survey concerning diagnosis and treatment planning for each patient. Six weeks later, they gave the raters the same records for the same patients. However, on this occasion, they included the lateral cephalogram.
A primary outcome was not pre-specified. However, the following areas were addressed within the 7-question survey: diagnosis (skeletal, dental or both); Angle’s classification; completeness of information; space conditions; and a perceived requirement for extractions, maxillary arch expansion and orthognathic surgery. They used kappa values to assess the agreement between the responses at the two time-points. This is the key assessment relating to the value of the cephalogram. They also measured the agreement between raters using Cronbach’s alpha.
What did they find?
All kappa values were high (ranging from moderate to near-perfect). This suggests that the inclusion (or omission) of a cephalogram had little effect on either diagnosis or planning.
In terms of treatment planning, the agreement concerning the need for extraction, expansion and orthognathic surgery all ranged from moderate to substantial. There was less agreement concerning the aetiology of malocclusion, which may reflect the inclusion of relatively mild cases.
Interestingly, more participants did suggest that additional records would have been helpful during the initial evaluation (37%) than during the later assessment with the cephalogram available (21%). A small number of raters felt that a cone-beam CT would have been useful both during the initial evaluation (7%) and indeed, even when the cephalogram was available (5%). They also found that the level of inter-rater agreement was acceptable.
What did I think?
I thought that this was an interesting, defined study with a simple question. They wrote the paper very clearly and incorporated a thoughtful discussion of the merits and limitations of lateral cephalograms. It is not overly original, however, with numerous similar studies published in the past. Nevertheless, the findings are mostly consistent with earlier studies on this topic. They should make us question further our prescription of lateral cephalograms.
The sample size is significant, with 100 sets of records evaluated. I imagine that this would have been quite an undertaking for the raters. The number of raters was relatively low and did include more residents than qualified orthodontists. It may have been interesting to include more experienced practitioners within this cohort. Furthermore, background information, including the raters’ typical approach to imaging, would have been useful. Indeed, it would be interesting to note whether involvement in this study has influenced their own radiographic prescribing.
Like much of the research we read, the findings from this study could be interpreted and applied in more than one way. The message seems to be that lateral cephalograms may have limited benefit in terms of decision-making. So should we take fewer cephalograms or at least be more discerning in terms of our use of cephalometry? Or could we conclude that we should replace the two-dimensional cephalogram with focused use of CBCT?
Emeritus Professor of Orthodontics, University of Manchester, UK.