11 - 14 to 7 and now 7 to 3? (aligner literature Part 2)

Accelerating orthodontic tooth movement is still a topic of active debate. Speakers presents nicely treated and “accelerated” patients in almost any orthodontic convention, while the literature started to provide some evidence that it does not change that much to use accelerating non-invasive devices.To keep updated easily on the latter scientific arguments, Kevin O’Brian’s blog it’s probably the best way as he has taken a keen interest in the matter and invariably post any new scientific update

Accelerating orthodontic tooth movement is still a topic of active debate. Speakers presents nicely treated and “accelerated” patients in almost any orthodontic convention, while the literature started to provide some evidence that it does not change that much to use accelerating non-invasive devices.To keep updated easily on the latter scientific arguments, Kevin O’Brian’s blog it’s probably the best way as he has taken a keen interest in the matter and invariably post any new scientific update (Kevin’s blog has become one of mine weekly fixed orthodontic education appointments, as well as the monthly appointment with new issues of the major orthodontic journals).

Whenever I saw impressive “accelerated” results I have always wondered what could have happened if the same treatment speed (weekly change of aligners instead of 14 days, now cautious change of aligners every 3 ½ days instead of 7?) would have been used without accelerating devices. Very simply no-one is testing it.Most of us would think that’s insane to move as fast without any re-assuring vibrating or flashing teddy bear to hold in our hands, convincing ourselves and the patients that’s something that will allow to achieve the desired speed in a safe manner. We miss biologic fundamental studies related to treatment speed, and in absence of solid guidelines, everyone can claim what he thinks it’s “true”.

Personally, I strongly doubt of vibrating or lightning accelerating devices. While specifically thinking to clear aligner orthodontics, they claimed the capability of accelerating movements from 14 to 7 days. Ehm… what did they say when Invisalign claimed officially that it was their official new recommended speed since fall 2016? I am not aware that vibration or light devices were integrated into clear aligners…Behind this new recommendation there seem to be the wise work of Dr Wheeler, former Professor of orthodontics at the University of Florida College of Dentistry for 28 years. Furthermore,

he also has been funded by Align Technology for several prospective clinical trials to examine tooth movement and by BAS Medical to examine the effect of relaxin and OrthoAccel to examine the effect of Acceledent on tooth movement.Taken from his linked-in public profile

He was sponsored by Invisalign for some research on efficacy and timing of aligner change, and this is always honestly disclosed in every published paper.In the 2014 AJODO paper

Variables affecting orthodontic tooth movement with clear aligners.Chisari JR, McGorray SP, Nair M, Wheeler TT.Am J Orthod Dentofacial Orthop. 2014 Apr;145(4 Suppl):S82-91. doi: 10.1016/j.ajodo.2013.10.022.PDF link (publicly available)

he anticipated of more than two years the weekly instead of bi-weekly change. Of course, he couldn’t clearly give this recommendation at that time, probably because of duties towards the funders of research or because the research was still work in progress. Anyway, he placed something very interesting on the wall for those who want to read it.

The research team checked weekly for tooth movement, with a regimen of aligner changes every two weeks. During the first week teeth were regularly moving, while during the second week almost nothing was happening. Does the second week of treatment was really useful and/or necessary as part of the treatment? Or was it just a sort of wise recommendation to follow blindly?Today we know the answer, at that time this paper and this graphic passed barely unseen.He also very interestingly found that the Invisalign aligners, before Smartrack arrival, were able to achieve only 57% of the planned movement (we discussed of this topic in the previous post).He recently published on the Journal of Clear Aligners, the official journal of the European Aligner Society who’s striving to stimulate some scientific interest around aligner therapy.

Effect of aligner material on orthodontic tooth movement.Wheeler TT, Patel N, McGorray SJournal of Aligner Orthodontics 2017, 1:21-27Abstract link

The main objective of this paper is assessing the effectiveness of Smartrack material in reproducing the planned clincheck vs the old material, as discussed in the previous post.At the end of the discussion, the Authors find the place for introducing an unsupported sentence (in the paper there are no tables, nor pictures relative to it).

Our study also shows that the majority of the tooth movement is expressed by day 3, another 5% is expressed between day 3 and 7. It should be remembered that this is for a tipping tooth movement of a central incisor and might be very different for rotational movement or other teeth. However, the clinician can use this information as a guide to determining how often à patient should change aligners.

What do I think?

This is a strange way to write a paper, and I can give my interpretation with the help of reverse psychology, being also frequently an author.The team found very interesting results about materials, but they also checked for timing of aligner change. They found out that after 3 days, the biggest part of the movement imposed by the aligner is achieved, as well as in the past the same team assessed that it was almost completely done during the first week. But, they do not present any table or picture to support what they state at the end of the discussion. This is normally not accepted in scientific papers as it’s an unsupported sentence in the discussion and just reflects the personal opinion of the authors.I am anyway thankful to the referees who didn’t notice this basic error, as it leaves the chance to the Authors to express a sibylline sentence (that may be object of a further paper).Dr Wheeler and his team are credible and serious researchers, and they would not share such an interesting fact just as a simple show off. They were aware of having in their hands an important piece of information and felt the urgent need of sharing it with the rest of the orthodontic community.An imaginary graphic representing the effect of weekly aligner changes monitored every 3 to 4 days may be something like this

The dotted yellow line represents the planned movement, the blue step line represents the actual way of achieving what’s planned (ending up at around 73%).I am purely speculating on an unsupported (but serious) sentence.What if it’s true? Does it mean that we can change aligners every 3 ½ days without any accelerating device?I hope that the joint sponsorship of Aligntech and OrthoAccel won’t deny the right to disclose such eventually interesting results in the future.I personally started, before reading this paper, to change aligners every 5-day on a selected group of patients, and by now results are as good as with 7-day changes.I feel that 5-days per aligner = 6 aligners per month = 1.5mm per month of maximum movement is something reasonable and respectful of biologic standards, as far as we know. I don’t feel that extreme need of making things even faster, and for sure not to give to my patients the burden of an extra (vibrating or warming/lightening) expensive home task. It’s very probably unneeded.Researchers and those who are interested into finding new answers: there’s much to discover around this topic!Thank you to Dr Wheeler and his team to be like the Cumean Sybil and letting “chi ha le orecchie per intendere intenda” (“it’s written on the wall for those who want to read it”).* The Cumaean Sybil was one of the most famous oracle of the ancient world. In this post featured image as Michelangelo painted her on the ceiling of his masterpiece in the Sistine Chapel in Rome

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