March 26, 2020

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?

They stated:

“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  When I looked at these carefully, I discovered that one was an unpublished Masters thesis.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.

Final comments

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.

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Have your say!

  1. Kevin.
    I’ve been in practice for 41 years. Doing the Invisalign system for. 20 years. I do not jump into new appliances and techniques quickly. I find that there are certain problems treated better with fixed and others.better with aligners. For sure, moving teeth with plastic is different. I often think of my dear friend Vince Kokich Sr. and wonder what his thoughts on the current state of Orthodontics would be. Warmest regards to all my colleagues. Barry

  2. Thank you Kevin. I would like to add that in addition to the objective outcomes of alignment and occlusion, there should be more attention paid to the patient experience. Aligner therapy has significant differences compared with conventional orthodontic therapy from a patient perspective. Quality of life comes to mind, and importantly, ‘control’. Patients, especially adult patients, have greater autonomy, control of the equation of perfection of results vs. time in treatment with aligner therapy.There, they can very easily say “No thank you” to additional aligners. With fixed appliances the question is more frequently “How much longer until we’re done?”.
    Alignment and occlusion are important outcomes in orthodontic therapy, however, I would hope that future, prospective trials included the patient experience of treatment including quality of life and autonomy.

    • Allen, I believed that you touched the heart of the problem we face with invisalign and that is the basic treatment goals of orthodontics. Invisalign succedded in changing orthodontics to crowns only. X-rays belong to the past. Who needs pano or ceph? They belong to a different world, and further, they might harm the patients. I’m not kidding, but the change is here, and we are part of this change. You speak about alignment only. Alignment of the crowns I believe. Yes., the patients now enjoy the freedom to decide when its time to end the treatment. This factor is very important from the patient’s point of view. I dont remember in my 36 years of orthodontics that the patients told me that this alignement is enough and please take the braces off. The question is, how orthodontics will look 10 years from now? I’m happy I will be out…

      • Pano and ceph are for doctors, for Invisalign it’s additional information. Doctor is one who treats patients, Invisalign is just appliance for treatment.

  3. Clear aligner offer easier Cleaning of the teeth and the gums so rarely we suffering from the patients oral hygiene during treatment. For me this is the most advantageous thing I’ve seen

  4. Hi Kevin
    The Aligners are here to stay, is clear! What I see dangerous is to try to do heroic orthodontcis with them.
    I still believe in Fixed appliances, biomecanics and Micro screws, this seems to be essential to all good practice.
    We should coexist with the two systems, taking advantage of the best of each one.
    Best regards
    Carina Mora

    • I totally agree with you. There is a place for aligners in Orthodontics but just don’t be too heroic with it as you rightly said.

  5. If you are looking for health, function, stability, homeostasis, aesthetics, fixed appliances are required by necessity, there is no option.
    If you are only looking for a cosmetic result, removable aligners are an option.
    Other factors such as hygiene, comfort, appearance, invisibility of devices, are secondary factors to take into account but are not decisive if you want to achieve results with the highest standards.

  6. Why is the ejo publishing papers like this?

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