Clear aligners are not as good as fixed appliances: An update.
In early December, I posted about a systematic review that concluded that clear aligners were not as good as fixed appliances. In my post, I drew attention to several deficiencies in this paper. For example, the authors included a plagiarised study published in a predatory journal.
They have now published a correction in the EJO and still come to the same conclusions. I have had a look at this correction and the new findings of their paper.
What did they do?
In this correction, the authors removed the plagiarised article. They then redid the meta-analysis. This showed that fixed appliance treatment was still superior to aligner therapy.
What did they find?
“The removal of the plagiarised paper painted an even more bleak picture for aligners”.
“excluding this retracted paper doesn’t make any difference to our conclusions”.
Their overall conclusion was
“We apologise for any misunderstandings pertaining to the reduction of this study, though it does not alter the review’s conclusion to a substantial degree”.
What did I think?
In my previous post, I made some critical comments about this paper. This is because we need to ensure that papers that make bold statements are scientifically sound. I thought carefully about the effect of the removal of the plagiarized paper and its effects on their meta-analysis.
I found that removing the plagiarised paper resulted in a meta-analysis of two retrospective studies. When I looked at these carefully, I discovered that one was an unpublished Masters thesis. Importantly, this was an analysis of orthognathic patients. I feel that this is not relevant to routine aligner treatment.
The second paper was published in 2005 in the AJO. This paper was based on a retrospective sample of patients collected from one specialist orthodontist. Importantly, the aligner patients were the first 48 aligner patients that the practitioner had treated. Whereas, the fixed appliance group were routine patients treated after decades of fixed appliance experience. This means that this paper must suffer from proficiency bias.
As a result, I still stand by my previous conclusions. I’m afraid I have to disagree with their findings. I am sorry to be so critical, but we need to ensure that Journals and authors publish papers that are scientifically sound in their conclusions.
Emeritus Professor of Orthodontics, University of Manchester, UK.