March 05, 2018

What do we really know about orthodontic aligner treatment?

Orthodontic aligner treatment has been around as long as I can remember. But do we know if it really works?

Orthodontic aligner treatment is probably one of the greatest orthodontic innovations. It has changed the delivery of orthodontic care. It has made orthodontic treatment accessible to many people who did not want to wear visible appliances. For example, Invisalign has recently announced that it has treated 5 million people and they are expanding their operations to Invisalign stores. They have also introduced Invisalign teen to treat children.

It is, therefore, very clear that orthodontic aligner treatment is popular with orthodontists, dentists and patients.

I have never used aligners because my caseload has always been children. But I have several questions. It is interesting that these echo questions that were raised by David Turpin in an editorial in the AJO-DDO in 2005. He asked

“What type of patients can be treated successfully with Invisalign? Are the results the same for properly selected patients treated with either Invisalign or fixed appliances? Are treatment times the same? What do we know about patient acceptance and discomfort? Are oral hygiene complications significantly reduced with the use of aligners? And perhaps most important of all, what are the treatment limitations of Invisalign”?

He went on to state

“To establish a broad base of support within the profession, we need more well-designed clinical trials”.

What has happened since then?


I have done a search to see if there have been any trials that evaluate the effectiveness of aligners published since David wrote this editorial. I also had a look for any trials that are currently underway on This showed that there were ten trials registered.

When I looked at these 6 were comparisons of types of aligner and 6 were looking at the effects of the various methods of acceleration of tooth movement. Of these studies, six were recruiting patients, three were not recruiting and three had completed but were not published. So there is not much in the pipeline to answer David Turpin’s questions.

I have now thought of several specific questions. Here they are with the answers

Does it work?

It must “work” because so many orthodontists/dentists have treated so many patients.  If it did not work, then patients would not pay for the treatment and orthodontists would not provide it?

Is it as effective as fixed appliance treatment?

We do not know

How does it compare to lingual appliances?

We do not know

Can we treat children with aligners?

We do not know

Can it only treat mild malocclusion?

Despite the widespread use of aligners, I have never seen a case series of moderate/severe malocclusions treated well. Or have I missed something?

Does it work for extraction cases?

We do not know. I have seen some case reports, but these were cases with Class I molars that may have spontaneously aligned, in a similar way to serial extraction cases.

Is it essentially a good way of providing compromise treatment?



In summary, there has been surprisingly little research done on such a popular treatment. I have seen some case reports but not many. I have seen lots of ClinCheck cartoons, but these are not evidence. It appears to be a very sophisticated system requiring a lot of monitoring. Orthodontists appear to spend a lot of time reviewing their ClinChecks”.

Finally, we need to consider that perhaps we do not need any evidence for aligners, because it is obvious that they are effective?


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Have your say!

  1. Dear Kevin, thank you for this useful summary. Given the absence of reliable data, it is very concerning that our indemnity insurers talk of a disproportionate increase of orthodontic legal cases, almost entirely related to aligner treatment. Unfortunately these legal aligner cases are equally spread amongst specialist and generalist providers. Clinicians who prescribe aligners should thus be diligent in ensuring patient expectations and clinical outcomes are carefully discussed and agreed to before treatment.

  2. These are excellent questions you raise. The paucity trials or even case reports is either alarming, or simply a sign of the times. I willingly use the appliance despite the lack of evidence, think it does a very good job at most case types, can even do an excellent job with compliance and careful planning. I can see how some practitioners would wonder however. What would you consider the definitive evidence that ‘conventional braces’ constitutes standard of care as opposed to simply status quo? Suresmile does a better job than conventional but very few seem to care. I think my friend, the salesman has been coronated.

  3. Hmmmm wonder why they are so popular without any substantial or significant evidence?

  4. I love the comment of ‘Clincheck cartoons’ 🙂

    • Hi Kevin and Prof Singh,
      The ClinCheck “cartoon” is what took the manual sequential aligner system from the 40’s to where it is today. This software you mock is what made orthodontic treatment of significant malocclusion severity possible by programming of sequential movements as low as 0.12mm per aligner, it gave us an accurate 3D diagnosis and treatment planning tool and most importantly programs the manufacturing of the SLA on which aligners are made. It was the foundation of modern day sequential aligner treatment, without ClinCheck “cartoons”, there would arguably be no sequential aligner treatment option for patients, many more veneers would be placed, the lingual revival may never have happened and all orthodontists would be seeing far fewer adult cases, fixed appliances included. Yes, we spend a lot of time on the “ClinCheck Cartoon” because this is the fundamental skill required when treating patients well with Invisalign. We plan mechanics, differently diagnose if required, communicate with colleagues and patients, manufacture our custom made appliances and monitor our treatment all with this cartoon!

      • Well said.
        The Clincheck is perhaps the most valuable tool in consenting and informing patients of their options since Orthodontics was invented.
        Prof O’B openly admits he has “little or no understanding of Aligner therapy” nor the processess and procedures involved in the patient journey.

        I sincerely hope this is not due to a desire to “tell the patient what they need” rather than listen to their concerns and requirements and involve them in the process, from beginning to end.

        • Not sure what you mean by your comment. I have consistently lectured on the important role that information plays in consent. I have also published extensively on patient and not orthodontist outcomes in research. I think that I touched a nerve in describing the clincheck as a cartoon. This was a light hearted comment…

          • Fair point Kevin.
            But you only touched a nerve with the cartoon comment because you of all people are above that kind of thing.
            That kind of comment is usually made by “ivory tower protectionist” Orthodontists who feel themselves above such things as “involving the patient” or even considering “limited outcomes” at patients express wishes.
            (We both know which very close friends of ours bemoan the day patients ever became involved in choosing their desired objectives!)

            The “cartoon” nature of the Clincheck is of course a reality, in so far as it is entirely up to the Clinician to program and design a realistically achievable outcome, and of course only the Stage One of the Clincheck represents “reality”.
            I do believe however that when handled as intended, the Clincheck is a ground-breaker in terms of consenting and objective setting, and hence my objection to any belittling of the procedure.
            It would probably be ideal if ALL Orthodontic modalities were preceded by a Clincheck-style simulation, especially where multiple treatment options were to be considered.
            If ever I am presenting Invisalign cases I always like to show Stage One pre-treatment, and then a Stage One post-treatment upon which the Retainers will be constructed, as these then represent “reality”, probably far better than even Study Models, which may have been judiciously trimmed to show a false outcome.

            I have offered to spend a day with your friend and colleague PJS, to go over as many cases as wished for, and would be delighted to extend the offer to yourself if useful in obtaining better “evidence”.
            Still love your blogs by the way.

  5. This blog post is one of your weakest, Kevin.
    To say you haven’t seen moderate to severe cases treated well with aligners is essentially admitting you haven’t looked. Is there a blogger’s bias here? Admittedly, no treatment modality offers 100% “perfect” finishes; but comparable results can be achieved. Here is a link to 500 Invisalign cases. There are a range of finishes, but you will find many that were treated well.

    • Yes, I agree, I thought that I would be able to say more about this type of treatment, but I could not find much information. I guess that this made it a “weak” post. Thanks for the link, I will have a look at it and post additional comments.

    • Hi, I have just looked at your link and gone through the first 200 cases. I did see some difficult starts and good finishes. But most of these cases were simple alignments with pre-treatment class I molars. I suppose that these were the cases that I mentioned in my original post.

  6. Thanks for bringing up the topic of treatment with clear aligners and the lack of new research…and for using my 2005 AJO-DO editorial to initiate discussion. If my memory is correct, I was prompted to tackle this topic in 2005 shortly after one or our well-known aligner companies pulled all advertising from the American Journal of Orthodontics & Dentofacial Orthopedics because the AAO insisted on altering the advertising claims. The AAO invited the top five officers of the clear aligner company to meet with us to resolve all differences…an offer which proved elusive in 2005. I suggested that the company simply add the following phrase to the bottom of each ad – “NOT APPROPRIATE FOR ALL PATIENTS.” In answer to this suggestion, the room was silent and the meeting ended shortly thereafter with no decision announced…or even discussed. To be fair more than 12 years after publishing my editorial, treatment with clear aligners has surpassed all expectations, but where is the research to support the claims now being heard?

    • I agree with Mark Hodges comments. The critics of clear aligners are usually those who have either chosen to stay in the dark ages and have not treated any adults or children with clear aligners or who have only dabbled in treating patients with clear aligners and never really learned how powerful and healthier treatment modality compared with fixed treatment it truly is. You ask where is the research? Good questions. Yes it is lacking when you compare it to over 110 years of fixed appliance research. Let me counter your question with this one: So show me research from any critics that says it doesn’t work!
      Here is some evidence that shows it does work:
      1. 5-6 million successfully treated patients around the world 2. There is plenty of research which already proves that light forces applied by anything (including a young patient’s thumb of a customised piece of plastic) will move teeth safely.
      3.There are several conference held each year hosting doctors who successfully treat malocclusion to the same or better standards than fixed, with better oral hygiene and less periodontal problems and caries than fixed treatment, with less root resorption and less pain and in shorter time frames in many cases than fixed appliances. These claims are all backed by research which I will include in a book I am currently writing. You only need to visit one of these conferences to see the difficult cases which clear aligners can treat when used by an experienced doctor – which is a fact many fail to raise.
      Like brackets and wires, if you are not experienced at using them ( as some of our general dentists find) you will not treat to a high standard (e.g. board case results).
      That all said, much more research can be done, should be done and is being done. Sadly not at a fast enough rate but this is in part due to an old school approach that many universities have adopted towards this treatment modality. Clear aligners have been around in their modern form for 20 years now and are not going away. It is not a fad or phase. They are here to stay and those doctors who think they can achieve everything they need to with braces will see that in our modern world where the customer chooses their treatment option their businesses will shrink in size and they will be wondering what happened much like Sony was left wondering what happened to their market share in the music industry with their Sony Walkman.

      • This is an excellent post and one of those conferences that Dr. Seamaan mentioned just concluded in Venice, Italy: the European Aligner Society 2nd Congress. The attendees doubled from two years ago to over 600 (any larger in the future and they’ll have to look for a new venue or limit attendance). There was a significant increase to 14 or 15 chairs of orthodontic departments in attendance from around the globe including Dr. Robert Boyd, one of the original academic investigators of the Invisalign system.

        The presentations from over 30 speakers included diverse topics such as mixed dentition treatment, extraction treatment, the use of TADs, Class II treatment in the growing patient and the adult patient, accelerated treatment, integrated treatment with restorative dentistry etc. It is evident that the system is getting better and is enthusiastically accepted by the public certainly for adults and very slowly but steadily for preteens and teenagers. CAT may never be as good as a fixed multi-bracket technique but it will become a moot point if the public will not accept ” braces”. As has been pointed out to me by many fine restorative dentists, amalgam or better yet gold would be the only choice for posterior restorations if it was up to organized dentistry in the United States. What happened?

        FYI: the following link will take you to a couple of cases presented by the Department of Orthodontics, University of Rome.

        Lastly, it would be remiss of me if I did not mention that Dr. Seamaan was one of the invited presenters in Venice and gave an excellent and very well received presentation that was much appreciated especially by me!

  7. I am currently completing a randomized controlled trial comparing Invisalign to conventional treatment. We published one article so far in the Angle Orthodontist (Nov 2017) regarding discomfort differences. More to come as I finish more patients (n=80). Hopefully, it will add evidence to the discussion.

  8. It worries me that, even with poor, anecdotal clinical cases as our main “evidence ” we want to turn to, there are almost no far more basic studies into what aligners actually do, how reliable the ClinCheck programme (“cartoon” in your words) is – the time and effort that skilled practitioners like Dr Vlascalic and I put into it is a reflection of how the system is not ideal, unless very experienced. Everyone wants to race to the 4 premolar extraction cases before knowing if they can actually reliably, predictably, consistently trust the output from the aligner company in mild to moderate cases – many of those I see going badly wrong in my role as a clinical consultant on over 10,000 cases (and strangely these failures do not get published by companies and their Shills)

  9. I have treated Invisalign cases for over 15 years.. I find that Invisalign is VERY effective if : you use it like ANY other Orthodontic appliance. It’s not magic and won’t do many things conventional treatment will do . It is not effective at extrusion(duh).. but is surprisingly effective at closing open bites not related to tongue thrust.. Our criteria is : solve the big crowding and AP problems in phase 1 then finish with Invisalign teen.. the only thing comical About clincheck is taking it as gospel without using your experience to MAKE it work for you!!

  10. Despite Jack Sheridan’s invention of moving teeth with thermoformed plastic more than 30 years ago, we’re still struggling with clear aligner mechanics. The control of tooth movement has improved markedly, but it is not equivalent to the same standard as fixed appliances. In our part of the world, we struggle with bi-maxillary protrusion in the absence of crowding. Interestingly, extraction cases in teenage patients are easier to manage as the forces applied can be expressed at the root level at this age, as opposed to adults.

  11. Hi Kevin – contrary view here:

    I think there is a huge amount of research with clear aligners, particularly Invisalign clear aligners. Probably more research than any- I shall say that again in capitals- ANY other variety of orthodontic treatment since records began. The thing is, none of the research is public domain, but is simply conducted by the practitioners treating the millions of Invisalign patients. Every time someone sends in records for a “refinement” or ” additional aligners” the Invisalign company knows how well the teeth moved with the previous set of aligners that they made.

    Now maybe someone didn’t wear their aligners or elastics as directed, but that can happen in any study with any ortho treatment. You can’t determine if a patient didn’t have a request for additional aligners because it all went well first time or they just never came back, or the dentist gave up and resorted to some other system.

    Plus Invisalign never see the finished result unless the patient gets Invisalign’s own brand retainers.

    But the numbers that they do have are colossal, literally n=millions and will tell them plenty. I have no idea if that evens out the other variables that are at play but smarter people than I probably do know what that data can be used for.

    Stephen Murray

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