Another nail in the coffin of the non-extraction obsession: a new study
Do extractions influence facial aesthetics? A long-term study.
In some of my previous posts I have discussed the effect of extraction/non-extraction on facial profile. However, I managed to miss this paper that was published last year. I feel that it certainly provides us with useful information.
As we all know, the extraction/non-extraction debate continues to rage. There are strong views on either side. While some are extreme and even verge on scaremongering. Others are more reasonable and point out that it is not the extractions that may cause damage to facial profiles. It is much more likely to be a consequence of poor treatment mechanics.
This paper was published in the EJO in 2015
Guilherme Janson et al
Eur J Orthod (2016) 38 (3): 272-280 doi:10.1093/ejo/cjv039
The authors did this study to find out if there is any effect of extractions on facial aesthetics and perceived age of patients.
What did they do?
They took a sample of 63 treated patients who had the following characteristics:
- Class II division 1 malocclusion
- Their age was greater than 21 years old
- Availability of records
- Frontal and lateral extra-oral photographs taken a minimum of eight years after their treatment.
They divided them up into three groups:
- Non-extraction treatment
- Two maxillary premolar extraction
- Four premolar extraction.
They had treated the patients with edgewise fixed appliances using a standard set of mechanics.
Interestingly, they used headgear to reinforce anchorage in the non-extraction and four premolar extraction groups. They used class II elastics when necessary.
They recorded the following data;
- Post-treatment occlusal outcome with the HBO system
- Cephalometric data (a large amount)
- Post-treatment lateral and frontal extra-oral radiographs
They standardised the images and showed them to a panel of raters. This group used a 10 point scale to record facial attractiveness and their perception of the patient’s apparent age. 76 orthodontists and 83 lay people made up the rating panel.
They carried out an appropriate statistical analysis and sample size calculation.
What did they find?
They presented a large amount of data. I certainly did not look too closely at the cephalometric festival of multiple variable testing!
I thought that the most important and relevant finding was that there were no clinically significant difference in any of the morphological measurements between the groups at the post-treatment stage.
Importantly, when they looked at facial aesthetics and apparent age, 8 years after treatment, there were no differences.
What did I think?
I will start my summary by considering the factors that may lead to bias in this study. I felt that these were;
- This was a retrospective study based on the availability of records. It must, therefore, have selection bias.
- They did not randomly allocate the treatment decision. This could lead to operator bias.
- The raters recorded their impressions from still life photographs. This does not necessarily represent real-life social interaction.
I have thought about the effect of these factors and I think that the most important is the selection bias because of the retrospective data collection. This means that we need to assume that they may have collected the records of the “best” treatments. As a result, this data may only be relevant to high quality treatment. We can only conclude that they found no difference between extraction and non-extraction treatments when high quality care was provided. I can also interpret this as meaning that it is not the extraction decision that may cause facial damage; it is more likely to be the choice of mechanics. I cannot help thinking that this type of treatment is not done by many orthodontists with the increased use of functional appliances and improved methods of reinforcing anchorage.
Nevertheless, if we consider that it is not possible to randomise the extraction/non-extraction decision, then their methods are likely to be “as good as we can get”.
I have thought about their conclusion and we need to remember that “absence of evidence” does not mean “evidence of absence”. It simply means that they did not find any evidence of harm from extraction treatment.
When I put all this information together, I cannot help feeling that this paper reinforces information from other studies that I’ve posted about before.
My overall conclusion from the literature and this paper is;
“We have not found any evidence that extracting teeth as part of the course of orthodontic treatment causes any harm to the facial aesthetics of our patients”.
I think that I will carry on amputating body parts (teeth) for patients in which I feel extractions are necessary.
Finally, I wonder if it is almost time to stop discussing orthodontic extractions?
Emeritus Professor of Orthodontics, University of Manchester, UK.