3D assessment of Carriere Motion 3D appliance
We are now seeing more papers on the Carriere Motion appliance. This sectional fixed appliance provides a Class II force to correct buccal segment relationships. There has not been much research on this treatment method, and this new paper adds to our knowledge.
I have posted about this treatment method several times. In these posts, I have been critical of the claims made by the inventor and Henry Schein Orthodontics. This is because there is no evidence to support the following claims that they make.
- The appliance distalises the upper buccal segments.
- Treatment encourages forward positioning of the mandible
- It shortens treatment time by 3-6 months.
- It increases the airway volume.
I have checked the company’s websites, and some of these claims have disappeared from the advertising. However, they still link to the video in which some of these claims are made.
Over the past few years, several research projects have been into the Carriere Motion. I have posted about them before. My overall feeling about these papers is that they outline early steps in research. They suggest that the main effects of this appliance are not very different from Class II elastics or functional appliance.
A well-known team from Michigan, USA, did this new study. The AJO-DDO published the paper.
Elizabeth V. Biggs, Erika Benavides, James A. McNamara, Jr, Lucia H. S. Cevidanes, Flavio Copello, Ronald R. Lints, Joel P. Lints, and Antonio C. O. Ruellas,
AJO-DDO online: https://doi.org/10.1016/j.ajodo.2023.05.031
All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest; none were reported.
What did they ask?
They did this study to:
“Quantify the outcomes of adolescent patients with Class II malocclusion treated with the Carriere Motion 3D appliance combined with fixed appliances”.
What did they do?
They did a retrospective case series study without a control. As a result, they measured the effects of the appliance and normal dentofacial growth.
The team collected the records of 28 patients who had completed their orthodontic treatment in one private office.
The main inclusion criteria were that the patients had a Class II malocclusion, completed treatment, and had full records.
They collected scans of the patient’s teeth and CBCT images taken at the start and end of the Carriere treatment and when it was completed with fixed appliances.
The team recorded and analysed many measurements with simple univariate tests across many variables.
What did they find?
They evaluated the 28 sets of records and excluded six of them for having a missing scan, the duration of treatment with the Carriere exceeded 12 months, and technical issues with data. This was an exclusion rate of 21%.
The mean age of the patients at the start of treatment was 13.5 (SD=1.6) years. At T1, this was 14.1 (SD=0.2) years; at T3, the mean age was 15.6 (SD=0.5). The mean duration of treatment with the CMA was 7.3 (SD=2.4) months; at the end of all therapy, this was 26 (SD=6.8) months.
The clinicians had taken CBCTs at the start of treatment (T1), at the end of the Carriere treatment (T2) and at the end of all treatment (T3).
They provided a large amount of very detailed data with multiple statistical tests. As usual, when I see a paper like this, I concentrate on what I feel is the most important outcome data.
These were the relevant skeletal measurements. I have included the means and standard deviations in brackets.
| Variable | T1 | T2 | T3 |
|---|---|---|---|
| SNA | 82.0 (4.3) | 81.8 (4.3) | 81.7 (4.4) |
| SNB | 78.3 (4.2) | 78.1 (4.0) | 78.3 (4.3) |
| ANB | 4.1 (1.5) | 3.9 (1.5) | 3.5 (1.4) |
| SnGoGN | 27.9 (3.3) | 28 (3.1) | 27.9 (3.4) |
There was also a large amount of data on tooth movement, which I found difficult to interpret. I hope that I have extracted the main points here.
“The upper molar derotated by -5.1 degrees during CMA treatment. Some of this was lost during fixed appliance treatment making the average -3.5 degrees.”
“The maxillary molar distalised -0.9mm during CMA treatment and rebounded during FA treatment to 0.1mm”.
“The upper incisor was proclined at 2.1 degrees by the CMA and further proclined during the FA phase to a total of 7.3 degrees. Similarly, the lower incisors were proclined 3.7 degrees by the CMA, and this was increased to 8 degrees following the FA treatment. In effect, the therapy flared the upper and lower incisors”.
I could not find any data on airway measurement or information on the overall quality of the treatment result.
What did I think?
Seeing more research into this treatment method and philosophy was good. However, we must consider that this traditional retrospective study has the following issues.
- There was marked selection bias. This was particularly characterised by the high exclusion rate of cases. This is of more concern when we consider that some cases were excluded because they took too long. This is similar to excluding patients from a medical clinical trial because they were not “getting better”. I am surprised that the AJO referees did not pick this up.
- The team presented a lot of data subjected to multiple selective statistical analyses. This means that there is a high chance of statistical false positives.
- Most importantly, there was no control group. As a result, we have no idea whether the changes were caused by the treatment or by normal growth. The study team pointed this out and suggested that enrolling an untreated control group and subjecting the patients to multiple CBCT exposures would not be ethical. I agree, but we must remember the lack of control when interpreting the results.
- I am also far from convinced that taking multiple CBCT images of growing children is ethical without clear clinical reasons.
The other important factor we must consider with this paper is the tiny effect sizes. In fact, they are not clinically significant. This leads us to conclude again that the Carriere appliance does not seem to do much and is perhaps a complicated method of applying Class II force.
Finally, this study does not support the claims made by the inventor and manufacturer of the Carriere Motion appliance.
Emeritus Professor of Orthodontics, University of Manchester, UK.
“Proclining incisors is suicide”–Hayes Nance
Why do we keep beating a dead horse?
Sometimes proclining teeth from their starting point is jsut what is needed
I totally agree with all your comments. Seems to me an unnecessary step. I would stick to Twin Blocks followed by Class 2 elastics on Fixed appliances.!
Taking radiographic images on children without a medical diagnostic value??
We are not treating cancer pts.
1. I can’t see how the Carriere device would procline the upper incisors. I think that ever since Lysle Johnston retired, the folks in the Wolverine state probably forgot how to close extraction spaces so they have to procline the incisors just to get the teeth straight.
2. It may not be fair to say that the Carriere device “doesn’t do much.” Its that it probably doesn’t do much that’s very different than any other Class II device (except for rotating the molars more, probably). That is to say all Class II correctors (Herbst, Forsus, Twin Block, intermaxillary elastics, headgears and biteplanes, and Carriere Motion appliances) pretty much seem to work all the same. Uncouple the occlusion and allow the mandible to outgrow the maxilla which in growing patients it usually will. Maybe hold the maxilla back a bit and maybe hurry up the mandible (but not really very often, if at all, make it bigger than it would have got anyway). So if everything does pretty much all the same thing, which do you choose? I actually like the Carriere because its less bulky, its easier to put it on and take it off, it has less irritation, easier emergencies, and its easier for the patients to keep clean, The drawback is you gotta talk the kids into wearing their rubber bands. I’d rather do that than deal with all the other stuff.
Most of the Carrière Motion papers primarily focus on the sagittal perspective of Class II and maxillary teeth, basically on normal to low angle patients. Unfortunately, the vertical dimension and the condition of the mandibular teeth are often neglected, despite their importance, which can potentially jeopardize the results.
One paper might provide some answers to the ‘whys’:
Amm E, El Amm C, Vaden J. Effect of Class II elastics on different mandibular arch preparations stabilized with aligners and stainless-steel wires: A FEM study. Orthod Craniofac Res. 2022 Nov;25(4):520-529. doi: 10.1111/ocr.12564. Epub 2022 Jan 27. PMID: 35015923.
Thank you for your clear synthesis.
I find that your final comment “is perhaps a complicated method of applying Class II force”, does not really fit. One can argue that it does not produce any of the effects that are usually claimed, but to say that it’s complicated seems a prejudice as it’s probably one of the simplest tool, together with CLII elastics to correct a CLII.
In a few words…They are literally trying to reinvent the wheel.
It’s more like they are trying to improve the square so it rolls better.
Since the Carriere is not attached to the upper incisors, what caused the “flaring” of the upper incisors during the active Carriere stages of treatemnt? Seems weird, but perhaps if there were a lot of Div 2 type incisors in the study you may see some facial tipping as the occlusion is relaesed by either the retainer on the lower or bite turbos on the posterior. I can’t access the full article, dont want to subscribe( pay….sorry) to see the entire article and look at all the initial dental parameters so it is hard to say. The large ” flaring” of the upper incisors after fixed appliance therapy could also be due to many different issues, including the starting point of the incisor orientation. If there were even 3 or 4 Div 2 cases included in the study, that could throw the average incisor relationship more towards starting retroclined, in which “flaring” would be a desired treatment result. It’s funny how the term “flaring” gets everyones fight or flight response going, when in some cases its what is called for. Perhaps a less prejudicial term like uprighting or torque correction is better served. The Carriere is another appliance in the long line of elastic based Molar rotation and “distalization” appliances. I am sure if you query those who use the appliance, me included, you’d find a happy group of practitioners that use a clean, easy to apply Class 2 and 3 correction device that has no unwanted recipricol non-compliant patient issues. My interpretaion is that the findings of the study are mostly insignificant clinically because of the design and small sample size. In regards to the elimination of patient who were not correcting, what was that lack of progress due too? If you are studying the efffects of an elastic based orthodontic appliance and patients in the study are not wearing their elastics, you would have to remove them from the study. Were the reasons for the exclusions due to lack of progress given? If was non-compliance then they should absolutely be eliminated from the study. The aim of htis study was to evalaute the effects of the appliance as it was being used as designed. Not to evalaute the compliacne levels of the participants. Back up for non-compliance in my office is ext of 5/12 or 5/12/21/28 or surgery. So those cases would have had treatment outcome numbers that were not compatible with the study.