Early Class III protraction treatment works and reduces the need for orthognathic surgery: A trial that shows us something useful!
Early Class III protraction treatment works and reduces the need for orthognathic surgery: A randomised trial that shows us something useful!
Once in a while a study team carries out a trial that provides us with very useful clinical information. This post is about a paper that shows us that early Class III protraction facemask treatment reduces the need for orthognathic surgery. All dentists and orthodontists should read this paper.
One of the main aims of early orthodontic treatment for 7-8 year old children is to reduce the complexity of any treatment that they may need later in their development. There have been several studies into early treatment for Class II malocclusion. These have all shown that any benefits are somewhat limited. However, until now we have had no strong evidence on class III treatment. This paper is, therefore, not only interesting but important
Nicky Mandall, Richard Cousley, Andrew DiBiase, Fiona Dyer, Simon Littlewood, Rye Mattick, Spencer J. Nute, Barbara Doherty, Nadia Stivaros, Ross McDowall, Inderjit Shargill & Helen V. Worthington
Journal of Orthodontics, 43:3, 164-175, DOI: 10.1080/14653125.2016.1201302
Dr Nicky Mandall led this project. I worked with her when she was a resident and then Senior Lecturer in our Department, they were great times for our orthodontic research. This paper represents 10 years of work by the investigators. The study was mostly based in the North of England, although there are some people from the “beautiful South”.
They did this study to find out if “early” class III protraction facemask treatment influenced the eventual need for orthognathic surgery. This was a multicentre two armed randomised controlled trial that started in 2003 and this paper represents a long-term follow-up.
What did they do?
Participants were 7-9 year old children with a Class III malocclusion. This was defined as three or more incisors in cross bite with a clinically retrusive mid face. They recruited the children through school screenings and treated them in 8 UK-based hospital orthodontic departments.
They randomly allocated the patients to receive either
- RME and protraction headgear
- No intervention, this was the control group.
They followed a uniform protocol for the protraction headgear treatment. This continued until the reverse overjet was corrected. Once they completed active treatment no patients received retention. Some of the patients had upper arch alignment when they were 12 to 13 years old.
The patients in the control group were simply followed and some of them also had upper arch alignment when they were 12 to 13 years old.
The primary outcome was the need for orthognathic surgery. They decided on this by using a panel consensus. The seven orthodontists met and reviewed the clinical records to decide whether each patient needed orthographic surgery. Research assistants blinded the records so they did not know the treatment allocation.
Secondary outcomes were cephalometric variables and psychosocial status which they measured these with two recognised scales.
They carried out a sample size calculation and randomisation and concealment were good. The statistical analysis was appropriate.
What did they find?
They initially enrolled 73 participants and at the end of the study they analysed 32 in the control group and 33 in the protraction group. The groups were balanced at the end of the study. There were no differences between the groups for the patients who had received upper arch alignment.
When they looked at the need for orthographic surgery they found that in the control group 21 (66%) needed surgery. Whereas, protraction treatment reduced this to 12 (36%). This was a clinically and statistically significant difference between the groups.
They calculated the odds ratio to be 3.34 (95% CI 1.21 to 9.24). This means that the use of protraction surgery reduced the odds of needing surgery by 3.5 times. I calculated the numbers needed to treat (NNT) to be 3.6 (95% CI 1.9-21.6). Meaning that we need to treat 3.6 patients to avoid one episode of orthognathic surgery.
It was very interesting that they did not find any difference in A-P cephalometric measurements between the groups. They also showed that there was some reduction in maxillary and mandibular rotations for the protraction group.
Finally, there were no difference in the socio-psychological measures.
Their discussion was good and clear. When they looked at all their data they did not find any predictors for the need for orthognathic surgery.
What did I think?
I think that this paper could be a real “landmark” publication because it reported a good long-term trial that provided us with very relevant clinical outcomes. I was particularly pleased that the final outcome was relevant to both patients and operators and was not an indecipherable mass of cephalometric data.
It was interesting and relevant that the treatment did not have an effect on socio-psychological status. This is in contrast to the studies that evaluated early treatment of class II malocclusion, which showed an interim boost in self-esteem. This may be because the class III incisor relationship is not as obvious to a lay population as very prominent incisors. As a result, the children may not have been subject to teasing and bullying.
While I feel that this study is good, there is one point that we need to consider and this is concerned with the method of assessing the need for surgery. The operators in the study did this assessment. While they were blinded to the participant’s identities, there is a chance that they would recognise the patients who they treated. Nevertheless, because all the clinicians took a role in reaching a consensus, this effect should be minimised. As a result, I feel that this is likely to have minimal effect on the results.
In summary, this was an excellent study that the authors carried out reported very well. I’m sure that its findings will change practice.
Unfortunately, this paper is currently behind the Journal of Orthodontics pay wall, I have contacted the editor who has told me that it should have been published as open access and it will be available to everyone later this week. This is great news.
Emeritus Professor of Orthodontics, University of Manchester, UK.