March 16, 2020

The Carriere appliance works by moving teeth!

The Carriere appliance is a Class II corrector. This is promoted heavily by Henry Schein Orthodontics and their Key Opinion Leaders. They make many claims about its effectiveness, and I have posted about this several times before. I also discussed two low-quality papers that measured the effects of the appliance. One stated that it was effective, and the other suggested that it was not effective.  This new paper looked at its effect on the dentition in three dimensions using CBCT technology.

A team from St Louis, USA, did the research. The Angle Orthodontist published the paper.

The Class II Carriere Motion appliance: A 3D CBCT evaluation of the effects on the dentition

Daniel Areeponga et al

Angle Orthodontist: On line. DOI: 10.2319/080919-523.1

What did they ask?

They did this research to answer this question about the Carriere appliance:

“What are the three-dimensional treatment changes of the Carriere Motion Appliance in Class II adolescent patients”?

What did they do?

They carried out a retrospective investigation of a case series.  They analysed a sample of 59 adolescents (16 boys and 43 girls).  The inclusion criteria were

  • Unilateral or bilateral Class II molar relationship.
  • Bilateral Class II canine relationship
  • Bilateral use of the Carriere Motion Appliance (CMA)
  • Availability of pre-treatment (T1) and post CMA use (T2) CBCT measurements. They defined T2 as successful completion of molar correction.  The clinicians took these CBCT images after a mean interval of 4 months. I am not sure that many orthodontists can justify this radiation exposure?

They divided the patients into two groups depending on the skeletal classification. Group 1 comprised 27 sets of records with an average ANB of 2.9 degrees. Whereas, Group 2 was 32 patients with an average ANB of 6.06 degrees.

They collected the case records from the offices of Drs Paquette, Shipley and Schreiner. These three well know KOLs are paid by Henry Schein Orthodontics, who market the CMA.  You know where this is going! But more about this later.

They did not provide any information about the numbers of participants treated by each orthodontist. They all used the standard CMA protocols.

The primary outcome measures were treatment duration and analysis of three-dimensional tooth movement.

What did they find?

The mean treatment duration of the molar correction was 4.9 months for group 1 and 4.2 months for group 2.

They presented a large amount of data on dental changes.   Importantly, they measured 36 variables for each group and ran univariate statistics across all of them.  This approach is bound to find many statistically significant differences.  Indeed, there were differences for nearly all the variables.

As with most cephalometric style papers, most of the effect sizes were small. I do not have the space to present these here. Nevertheless, I would like to illustrate the data with the movements for the upper molars for group 2. I also calculated the 95% confidence intervals from the standard deviations that they presented.

The data showed that the upper molars moved distally by 1.67 (95% CI= 1.12-2.2)mm, tipped distally by 6.45 (4.8-8.0) degrees and rotated distally by 4.64 (2.6-6.2).  These wide confidence intervals reflect the small sample size and the high level of uncertainty in this data.  All these small differences combine for overall molar correction.

The authors nicely  summarised the clinically important effects as:

  • Distal movement and the tip of the upper canines
  • Distal movement and the tip of the upper molars
  • Mesial movement of the lower molars
  • Flaring of the lower incisors.

In effect, the CMA acted like Class II elastics.

They concluded:

“The CMA corrected Class II malocclusion through distal tipping and rotational movement of maxillary canines and molars and corrected mesial tip of lower molars”.

What did I think?

I thought that this study was interesting because the authors had adopted the simple approach of evaluating a case series. While this was a low level of evidence, it does illustrate the effects of the appliance.  Importantly, their conclusions reflected the study design and they did not make any other claims for the effectiveness of the appliance. This could be a good “first step” paper.

Nevertheless, we need to be careful in interpreting their findings for the following reasons.  Importantly, there was not a control group. As a result, we must assume that some of the tooth movement will have occurred during natural adolescent growth and is not due to the CMA.

Furthermore, the cases had all been successfully treated. There was also no indication of how the patient records were selected. As a result, the sample could be subject to considerable selection bias.  It is relevant to point out that Drs Paquette, Shipley and Schreiner received substantial payments for their work as KOLs for HSO from 2016 to 2018 according to Open Payments. While there is nothing wrong with receiving these payments. Their conflict was not declared. I will just leave this here.

Final thoughts?

This paper shows that the Carriere Motion Appliance works the same as  Class II elastics. I cannot help feeling that the CMA is a heavily promoted expensive way of applying Class II mechanics?

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Have your say!

  1. Kevin

    I just read your review. A couple of things for you to consider. The author was given a list of all motion patients treated by the clinicians listed in the article. Final case outcomes were not in the selection criteria. In fact some of the patients in the lists provided had not even finished tx yet. The patients were provided by a search of practice management systems and the three offices did no pre eval of the patient lists provided. Given the nature of the method of identifying patients treated with a motion appliance, the patients could have worn or not worn elastics well and would be included on the list. The selection of included patients was never revealed to the clinicians by the author. We also had zero input on the write up of the article and because we were unaware if or when an article would be published, we had no opportunity to declare any conflicts, although all three of us would have been happy to do so.

    We were not surprised whatsoever on the author’s findings, in fact if you have heard any of the HSO KOLs present on motion treatment we describe the effects of motion to be essentially the same as every other Class II corrector, just simpler for the patient and the clinician to manage (in our opinion). It was actually nice to see that our clinical impressions were borne out by this investigation.

    Your ongoing reviews continue to be helpful to keep orthodontists informed on a wide range of topics from numerous journals. During the course of these reviews, you have frequently requested KOLs to provide data to support claims. I would think that openly inviting residents into our offices to do their research without any interference is the best way to obtain such data. Given the opportunity, in this case you failed to recognize that fact in your review and as such lost an opportunity to encourage more orthodontists to follow suit. I find that unfortunate.

    Dave Paquette

    • Thanks for the comments. Firstly, as I have mentioned many times previously. There is no problem with being a KOL for a company and receiving funds for promoting their products. However, it is essential that this conflict is declared. It was a shame that you did not do this.

      Secondly, the information that you gave on case selection should have been included in the paper. This is very basic scientific method and I am surprised that you did not appear to have input into the paper on the cases that you treated?

  2. I respect all your ideas but for me my caseses and my rezultes tell me another things .i used class 2 elastics many years but i never get my CMA rezults .l treat cases of 8 mm cl 2without frontal lower protrogen and Iess extraction casses and less upper protrogen especialy in casses with big upper crawding .i notice realy small amount of scheletal changes but we must dont forget the rapeditly rezults that we acheved in a small amount of time .in totall i am so happy that CMA is one of the important new appliances that make my practical life more easy .

  3. Let’s examine the evidence based orthodontics available for a change. I have seen ceph overlays on 9 Carriere Motion (formerly called distalizer) appliance cases. In all there is a range of 0-2mm of upper “molar distalization” likely due to some de-rotation. All of the remaining Cl II correction is from mandibular re-positioning forward. There is some dento-alveolar advancement of the lower incisors as a result of leveling the curve-of-Spee. I have seen no evidence of denta-alveolar advancement of lower molars. Any wonder why many cases relapse? Yes Cl II elastics is the force applied. But Cl II elastics demonstrate true dento-alveolar movement when wire extrudes from the distal end and mandibular re-positioning results when there is Cl II correction with no wire extruding from the distal end of the lower 6 bands/brackets. Why can’t we call this for what is it: mandibular re-positioning? It’s not rocket science! The notion that every Cl II case needs the mandible positioned forward is vapid thinking. I place the Motion appliance in the heap of Cl II re-positioning hope and pray appliances that have come and gone.

  4. So I suppose all those “Airway Claims” were for a different Carriere then? At this point, it is quite clear that, KOL claims notwithstanding, the Carriere does not do much of anything, except “tip” teeth (which may upright once fixed appliances are placed), and extrude the maxillary canines significantly. This seems like a rather sloppy mechanism of class II correction, with no vertical control. The conflicts of interest are very glaring, and unfortunately cannot be explained away by specious justifications. It really beggars belief that three offices of HSO KOL’s could only generate a total of 60-something patients using the Carriere. Were these 60 out of 600, where things seemed to work out? We will never know.

  5. Expensive Class II elastics indeed. They do however show that heavy Class II elastics are effective and this could be the reason that the Carriere device appears to be more effective than the light Class II elastics that are advocated by others.

    The cases presented on the Carriere website ( clearly show the changes illustrated in this study. There is also significant lingual tipping of the lower molars, with a significant AP cant of the teeth attached to the appliance. One of these “best” cases even shows significant recession on the mesial root.

    Heavy Class II elastics look good

  6. Kevin,

    I agree with you. We would have been happy to declare the obvious conflict of interest if given the opportunitiy. Perhaps this should happen with the journals during the process of reviewing articles under submission. I have had numerous residents from various programs harvest records from my practice over the years. In every situation there would have been a conflict of interest as I have been on advisory boards with multiple companies for over 30 years. Not one time have I been asked nor even had the opportunity to declare a conflict of interest UNLESS I was an author (which in the case of this article I am not). As you are aware, there was even a submission a couple of years ago where I declared the conflict of interest and the journal neglected to publish it and had to print a correction the following month.

    I also agree that case selection protocols should have been made clearer. For the past decade or longer when residents harvest records from our office, “study patients” are identified only by the resident. We provide them with read only access to our practice management system and send a copy of our entire CBCT database on a hard drive to the resident (all our patients sign a consent for research prior to starting treatment). We never know which patients are selected, what the selection criteria are, nor what the universe of patients is from which the sample is selected. In several situations the nature of the study completely changed once the resident began their sample search and I was unaware until their thesis was completed. That is because it is all done remotely. I recall several residents that I never even met until years after they had completed thier studies. I have occasionally been asked about brands/sizes of elastics used or materials used for attachments or brands/archform shapes of wires. So when I said access to records without interference, it is exactly that. I have been happy to allow residents to investigate any treatment protocols I use in my office and have intentionally removed myself from the process to remove any potential bias. I will continue to allow open access to residents and although I am rarely on their research committee, I will now suggest that they provide a clear description of sample selection to avoid similar confusion.

    Dave Paquette

  7. Having been the first ‘victim’ of the KOL of the month club, I wanted to quickly chime in on this blog post. I would like to echo what Dr. Paquette tried to say. I have had papers published on cases treated in my office. Most of the time, like Dr. P, I have no input into the studies, no knowledge of what patients they are using and certainly no say in what is written, nor published. Given that the articles are not done by us (and in the case of my articles my name is not even on the paper other than a thanks at the end for providing patients), I am not sure it is even appropriate to disclose our KOL status. And beyond that, I would argue that the publishing journal is more at fault in the case of this present article being reviewed rather than the doctors that provided the cases. I have argued for many years that if these journals are truly peer reviewed prior to being published, than the fault of studies that are deemed poor quality by Dr. O’Brien or others should be pointed directly at the journals for accepting them, not at the contributing authors and/or doctors.

  8. As I have mentioned in another post about the Distaliser i have tried only few cases. In all cases I found expansion f the upper canines and extrusion. Why died they not look at all 3 dimensions of toothmovement for a complete analysis ?

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