March 11, 2019

Does the Carriere Motion 3D Class II appliance influence the airway?

One of my recent posts was on theCarriere Motion II appliance.  I pointed out that there was no research on this new method of treatment. Since then I have come across this paper. This is my academic opinion on it.

I found this paper on Luis Carriere’s Facebook account, where he put up a post about the new research. This is the link.

As he is a major Key Opinion Leader for HSO and the Carriere Motion “all motion, all day every day”! I thought that I should have a close look at this paper because he thought that it was “very interesting”.

A team from Cairo, Egypt did the research, and the Journal of Dental Science, Oral and Maxillofacial Research published it.

Three-dimensional computed tomography evaluation of airway changes after treatment with Carriere Motion 3D Class II appliance.

KH Atta et al., J Dent Maxillofacial Res. (2019);2(1):16-19. DOI: 10.30881/jdsomr.00023

This is an open-access journal so you can easily access the paper.  It is also worth pointing out that this is classified as a “predatory journal and publisher”. These journals are defined by Wikipedia as;

“an exploitative open-access academic publishing business model that involves charging publication fees to authors without providing the editorial and publishing services associated with legitimate journals (open access or not). The idea that they are “predatory” is based on the view that academics are tricked into publishing with them, though some authors may be aware that the journal is poor quality or even fraudulent”.

What did they ask?

They asked:

“Does treatment with the Carriere Motion II appliance, for Angle Class II malocclusion, influence the airway space”?

Interestingly, this new research is directed at the new orthodontic speciality of “airway friendly orthodontics”.

What did they do?

They did a retrospective study and recruited patients from the outpatient’s clinic of their dental school.

The PICO was

Participants: Patients aged 14-30 with Class II malocclusion with well-aligned arches

Intervention: Carriere Motion 3D Class II appliance.

Control: None

Outcome: Total airway volume and minimal cross-sectional volume of the airway measured from CBCT images.

The CBCT scans were taken before treatment and at the end of the Carriere Motion 3D appliance treatment.

What did they find?

They found that there was an increase in both the total volume and cross-sectional area of the airway after treatment.  They presented the data in a simple way and explained what P values meant in their data tables. I looked at their data, and they reported that the total airway volume increased from 11.3ml to 15.2ml and quoted a difference of 4.9ml.  I used my iPhone calculator to work out that this difference was in fact 3.9ml! Here is the relevant data, corrected for the miscalculation for the mean difference in volume. However, the confidence intervals may not be totally accurate?

Outcome Pre-treatment Post-treatment Difference 95% CI of difference
Volume (ml) 11.3 15.2 3.9 4.2-5.5
Cross-sectional area (mm2) 171.68 212.78 41.0 329.7-52.2

They suggested that this was a  34% increase in airway volume and a 23% increase in cross-sectional area.

Their overall conclusion was

“The Carriere Motion II appliance produced the effect of mandibular arch protraction which in turn repositions the tongue anteriorly, increasing the airway size”.

What do I think?

To be honest, I am not sure where to start.  I usually would not review a paper like this. However, there is a possibility that this will be used as advertising and promoted by KOLs. In fact, this has happened already with the Carriere Facebook post.  As a result, I feel that this should be subject to reasonable scrutiny.

Firstly, this was published in a predatory journal. As a result, we cannot place much emphasis on its findings.  I also spotted that it was submitted on January 9th 2019 and published on February 12th 2019. This is insufficient time for peer review and copyediting.

Furthermore, the study suffers from significant flaws. In short, these are:

  • It is retrospective and subject to selection bias.
  • The method of measurement was not clear and subject to positional errors.
  • The measurement of the CBCT images was not done blind. It was also very subjective with the operator tracing the outline of the volume of interest with a mouse. This may lead to a high level of measurement bias.
  • There was no error analysis, and I felt that this was essential.
  • The subtraction of the means was not correct.
  • There was no untreated control or comparison group. As a result, the changes could have been due to normal growth.
  • The age range was large, and there was no sample size calculation.
  • The confidence intervals were wide representing a high degree of uncertainty.
My final thoughts

As a result, in my opinion, this is not a good piece of research, and it does not add to knowledge about this new form of treatment.

Do I think that this evidence can be used in advertising and KOL presentations? I agree with Dr Carriere that this data is “interesting”. Does it tell us anything about the Carriere appliance and “airway friendly orthodontics”? My feeling is that it does not.

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Have your say!

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    Hello, Kevin. Thanks again for your vigilance – alerting us to “those pulling levers behind the curtain”.

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    Who needs evidence in this Brave New World of orthodontics? Opinion and a good roi is all that is required. Promoted by Instadontists with many followers.

    Who needs evidence or a ceph study Lysle?

    I want to retire!

  3. Avatar

    In my humble opinion and purely anecdotal, I am equally, if not more, concerned about the long term effect on TMD related considerations. Does molar distalization open the door to a more posteriorly displaced condyle and, if so, is this more predisposing to TMD?

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      Really? How does that work?

      Where’s the evidence of this ever happening?

      I’m having trouble breathing. Will this affect my face? I’m very red!

  4. Avatar

    Thank you for sharing. This paper is an example of how not to conduct a study – bias, error, spurious data, mathematical inaccuracy and fallacious conclusions. It doesn’t even pass the basic test of Biological Plausibility. As you noted, this melange of dissimulation, will likely be used to further perpetuate the Airway scam.

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    Another lovely debunking of orthodontic mythology. Yet again, thank you Kevin!!

  6. Avatar

    Another lovely debunking if orthodontic mythology. Thank you yet again Kevin!

  7. Avatar

    If as posited Carrier Class II correction is achieved through dentoalveolar distalization of the maxillary buccal segments, shouldn’t the results show a retraction of maxillary incisors and a more restricted mandibular posture and airway? If on the other hand the Carrier device creates a dual bite with a forward posture of the mandible in Class I, similar to anti-snoring devices, then an increase in airway would be expected but only in the forward (dual bite) posture which reflects a distraction of the mandible and not the true centric relation position. Because we’re not growing mandibles anymore, right?

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    Let’s see, growing kids and no control group. Hmmm, I bet if they measured their feet they would find that Carriere treatment had a positive growth effect there as well.

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      Don’t scoff at that. There isn’t a day that goes by that I have not made boys grow ten inches by putting braces on them when they are 11 years old and voila, taking them off when they are 13 years old and much taller. Scientific proof for sure of my abilities.

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