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 ClinicalTrials.gov. 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?
Emeritus Professor of Orthodontics, University of Manchester, UK.