At last, a trial on aligners v fixed appliances in complex cases!
Most readers of this blog will be familiar with me moaning about the lack of high-quality research into clear aligner treatment. Recently, I posted about several new studies but pointed out that there are problems with the papers. I was, therefore, interested to see this recent paper on the effectiveness of clear aligners and fixed appliances for patients with severe crowding.
I am generally under the impression that clear aligners provide orthodontic treatment for mild to moderate problems. However, there are currently no trials of using aligners to treat more severe malocclusions. As a result, I thought that this paper was very timely and exciting.
A team from Syria did this trial. Cureus Journal published the paper.
Samer T. Jaber, Mohammad Y. Hajeer, Ahmad S. Burhan
Cureus 14(10): e30147. DOI 10.7759/cureus.30147
Now I wonder if you are thinking, “what is Cureus”? I was unsure, as I had not heard of this journal before I came across this paper. So, I started with Wikipedia, which describes it as follows;
“Cureus, also known as the Cureus Journal of Medical Science, is an open-access general medical journal and is among the growing number of journals using prepublication and post-publication peer review”.
They provide a rapid review and publication process. Furthermore, all the papers are open-access. I have looked very carefully to see if this is a predatory journal. I could not find any evidence that this was the case. Finally, I contacted the corresponding author to ask why this paper was not published in a mainstream orthodontic journal. He told me that they took this decision to enable rapid research publication.
So, let’s have a good critical look at this paper.
What did they ask?
They did the study to find out.
“What is the effectiveness and efficiency of in hour aligners compared to fixed appliances for premolar extraction complex orthodontic cases”?
What did they do?
They did a single centre 2 arm parallel group RCT. They registered the trial on ClinicalTrials.gov. The PICO was
Class I Orthodontic patients with severe dental crowding of more than 6mm of tooth size-arch length discrepancy.
In-house clear aligners
0.22 slot MBT brackets with TPA and lingual arch.
A single operator treated all the patients. They defined the endpoint of treatment when the patients had completed all stages of treatment, and two operators were satisfied with the end result of treatment.
They used pre-prepared remote randomisation. The team concealed the allocation by using sealed envelopes. As with most orthodontic trials, they could not blind the patients and operators to the intervention. However, they did data collection and analysis blind. They did a straightforward sample size calculation.
What did they find?
The team enrolled 36 participants. 18 (5 males and 13 females) were randomised to receive clear aligners, and 18 (7 males and 11 females) received fixed appliance treatment. No participants were lost to follow-up. The mean age of the participants was 21 years. There were no differences in Little’s index at the start of treatment.
They presented a large amount of PAR occlusal index data, and I will concentrate on this because it provides more information than Little’s Index.
|Group||PAR||% change PAR|
|Aligner||33.89 (8.01)||5.5 (2.85)||87.08|
|Fixed||30.44 (6.69)||4.04 (2.96)||83.5|
None of these differences were statistically or clinically significant.
I had a good look at the individual PAR score data to look for any differences in the components of the malocclusion. I did not find any clinically significant differences. The overall standard of care, according to the PAR index, was high.
The mean duration of treatment was 23.7 (5.2) months for the aligner group and 26.2(5.27) for the fixed group. This was not statistically different.
Their conclusion was;
“There were no significant differences between the clear aligner and fixed appliances groups for any of the component of the PAR index. In house clear aligners can effectively treat complex cases. There was no difference in treatment duration between the two interventions”.
What did I think?
This was a nicely done and written-up research project. The team followed the classical RCT methodology, and I could not find any significant sources of bias. The only one was possibly the assessment of the end of treatment. This appeared to be subjective, and the operators were not blinded to treatment allocation. However, this is a feature of many other orthodontic trials and reflects the “real world” assessment of the end of treatment.
My only other concern was that this was a single-operator study. This means that the findings may have limited generality. Nevertheless, this study is an excellent first step.
Good points were that the study was well done. The outcome measure (PAR) is well established and has been used in many trials. Notably, the index showed that the start dental malocclusions were relatively severe and that the overall treatment standard was high.
Finally, this study shows that orthodontic treatment with aligners is comparable regarding occlusal index scores with fixed appliances. It is a good and valuable study.
My only slight concern is that this paper would receive greater attention if the authors had published it in a mainstream orthodontic journal. However, I appreciate that they wanted a rapid review and publication of their work.
Emeritus Professor of Orthodontics, University of Manchester, UK.