What is it?

The appliance is a class 2 / class 3 corrector using intermaxillary elastics and a combination of sectional appliances and a removable retainer. It was launched in 2004 by Luis Carriere and was initially designed for class 2 correction. This blog focuses on Class II correction.

The appliance is marketed on the premise that it employs a sagittal first philosophy, aiming to achieve an ideal Class I posterior occlusion at the beginning of treatment prior to fixed appliance/aligner phase.

Design

The appliance consists of a sectional arm originally made of stainless steel but recently 3D Motion CLEAR was introduced which is clear polymer. The sectional arm extends from upper canine to upper first molar. The canine pad has a hook to attach a class 2 elastic. The attachment to the upper first molar has a ‘ball and socket’ feature, which enables mesial out rotation of the molar. A useful feature as 83% class 2 molars are due to the upper first molars misbehaving and rotating mesial in, worsening the class 2 appearance Henry 1961. The rigid design is intended to prevent unwanted tipping of the canine and the molar Carrière 2004. An attachment is bonded on the lower first molar, button hook or bracket, and a vacuum / pressure formed removable appliance.

Elastics

The elastic protocol consists of heavy elastics, beyond what is convention, with 8oz used in the protocol. The elastics are recommended to be changed every 4 hours initially, progressing on to every 2 hours! !  I have previously blogged on the choice of elastic use with orthodontic appliances,  (click here to view). The Carriere Motion Appliance elastic protocol is a new approach consisting of significantly higher forces and more frequent changes than have been previously proposed.

How does it works?

There are three proposed ideas of how the Carriere Motion Appliance works.

1. Distalisation of the upper posterior segment
2. De-rotation and uprighting of the upper first molar
3. Clockwise rotation of the occlusal plane

There is a growing body of evidence which helps to populate the extent to which the proposed mechanisms work. To put the changes into perspective a comparison has been made to the use of class 2 elastics (where possible).

Distal movement of the posterior maxillary teeth

Feature: The upper segment is distalised through the use of intermaxillary elastic. This movement is favourable in terms of anchorage as the 8 upper teeth (canine to first molar) are out gunned by the 12/14 teeth of the lower arch.  

Evidence: Upper first molar distalisation was found to be 1.80mm (Data adapted from Areepong 2020). To put the changes of the upper posterior segment into perspective class 2 elastics achieve slightly less distal movement at 1.32mm.

The distalisation effect equates to just over a quarter unit class 2 molar correction, which is not significant enough in itself to warrant selection over class 2 elastics. However the studies mentioned above looked at successful half unit or full unit class 2 molar correction cases only, therefore other factors are at play, and class 2 correction is only partially achieved by upper molar distalisation.

Carriere Motion Appliance wins (just)

Distal rotation of the upper first molar

Feature: The ball and socket joint is an interesting feature, permitting distal rotation of the molar whilst maintaining attachment to the rigid arm. The combination of a distal vector of force from the class 2 elastic results in a distal rotation of the upper first molar, the centre of rotation for this movement is claimed to be at the palatal root of the upper first molar.

Evidence: Daniel Areepong’s 2020 study found a 4.11° of distal rotation of the upper first molar around the palatal root of the first molar, correcting the commonly found mesial in rotation of class 2 molars. The upper molar distally tipped by 5.52°, aiding uprighting of the upper first molar. How do class 2 elastics fare, well there is far less favourable rotation at 1.64°, and similar distal tipping reported at 4° Uzel 2007.

It sounds like a winner, the Carriere Motion Appliance has distal rotation, and class 2 elastics do not. However, the mesial in rotation of class 2 molars is on average 14.5^o Henry 1956, which means the rotational effect of the Carriere Motion Appliance is not enough to achieve full correction for the average class 2 molar rotation.

Carriere Motion Appliance wins

Occlusal plane correction

A clockwise rotation of the occlusal plane results in a reduction of the class 2 molar and incisor relationship. However it can have unfavourable facial effect through further distal positioning of the mandible.

Evidence: Occlusal plane changes are relatively small with the Carriere Motion Appliance, with a clockwise rotation 3.9^o Kim-Berman 2019. Interestingly class 2 elastics effects are reported to be much smaller at 0.7-1.0 ^o , this was a surprising find in the literature, as from clinical experience I do notice a similar rotational effect from class 2 elastics, which maybe due to the method of assessments being cephalograms  Ellen 1998, Jones 2008.

Depending on the case a clockwise rotation may be favourable or unfavourable for the class 2 correction. A ‘shorty’ Carriere Motion Appliance has been created which is a shorter arm from first molar to first premolar, which is intended to reduce the occlusal plane rotational effects through closer proximity to the centre of rotation of the maxillary and mandibular dentition.

Carriere Motion Appliance  Loses

What else happens?

There are several other effects of the Carriere Motion Appliance which are observed in their use, which do not feature in their proposed mechanisms of class 2 correction method.

Mesial movement of the posterior mandibular teeth

Feature: A lower VFR is designed to utilise the lower arch as anchorage. Mesial movement of the lower posterior teeth is not seen as a favourable feature of the Carriere Motion Appliance, and through differential anchorage between the arches, is designed to limit mesial movement of the lower posterior teeth.

Evidence: After analysis of class 2 molar correction it was found the Carriere Motion Appliance resulted in lower molar mesialise movement of 1.94mm Areepong 2020. This is comparable to class 2 elastics of 1.5-3.4mm of mesial movement of lower molars (Janson 2013, Sorensen 2019).

Mesial lower molar movement is equivalent to the distal upper molar movement with the Carriere Motion Appliance, indicating the proposed differential anchorage does not appear to occur in clinical practice. When compared to class 2 elastics however there appears to be slightly less lower mesial molar movement. However, in certain cases, mesial movement of lower molars and the resultant lower incisors proclination may be a treatment aim, class 2 division 2 malocclusion for example. Should we leave off the lower removable appliances in such cases?

Carriere Motion Appliance Loses

Extrusion and rotation of canine teeth

Feature: Class 2 elastics typically result in tipping and rotation of the teeth bearing the attachment for the elastic. To prevent this the Carriere Motion Appliance is made of a ridged sectional stainless steel arm to the canine tooth, which has been proposed as a method to prevent such changes.

Evidence: Upper canines extrude 1.71-2.67mm and rotate 4.79° Areepong 2020 Sorensen 2019. Which sounds unfavourable, however when comparing to class 2 elastics a 4.29mm extrusion of canines occurs Sorensen 2019.

With the Carriere Motion Appliance design it does not appear the extrusive or rotational effects have been eliminated from the appliance, however the extrusion has been reduced in comparison to class 2 elastics. Variations exist in both appliances to reduce the extrusive and rotational effects, for the Carriere Motion Appliance the ‘shorty’ can be used, and therefore the canine is not incorporated into the appliance. With class 2 elastics hooks or posts can be added to the archwire to reduce the extrusive effects. With modifications to both approaches possible, it renders neither superior, however the clinician needs to be conscious of the likelihood of the effects and if favourable for the case.

Carriere Motion Appliance draw class 2 elastic

Lower incisor proclination

Feature: Through the use of a lower removable appliance and differential anchorage, less proclination of the lower incisors should occur, one can assume!

Evidence: Lower incisor proclination does occur at 3.74° Areepong 2020. Class 2 elastics are greater at 1.4mm (approximately 7^o) Nelson 2000.

Carriere Motion Appliance wins

Conclusion

Overall the Carrier Motion Appliance has some favourable effects over the use of class 2 elastics;  slightly more upper molar distalisation, favourable distal rotation of the upper first molar. As well as less of the bad; with less lower molar mesialisation, less canine extrusion and less lower incisor proclination. The appliance however still retains some of the hallmark issues of class 2 elastics; clockwise rotation of the occlusal plane, rotation and distal tipping of the upper canine and molar extrusion. However the research presented in this blog was limited through retrospective studies subject to bias. A systematic review has been done but it was not included in this blog as the 16 retrospective studies found mostly not comparable and a meta-analysis was not possible on most aspects Barakat 2021. It may have been somewhat premature to have carried out a systematic review at this stage without more primary studies, something Kevin O’Brien has highlighted in his blog (click to view).

Questions still to be answered are failures of the appliance, complications and patient related factors. Retrospective studies have collected examples of occlusally ‘success cases’, which helps answer how the appliance works and has been the main aspect of this blog, however it does not answer how effective the appliance is in ‘real world’ scenarios, the that prospective studies are required.

The appliance has some favourable outcomes over the use of class 2 elastics, however from the above table the differences appear to be small, especially for class 2 molar correction. 

Results from Areepong 2020 were adapted by me to calculate the mean values of the combined data, which the authors did not do in the paper.

References

Areepong, D., Kim, K.B., Oliver, D.R. and Ueno, H., 2020. The Class II Carriere Motion appliance: A 3D CBCT evaluation of the effects on the dentition. The Angle Orthodontist, 90(4), pp.491-499

Sorensen, J.V., 2019. A Comparative Study of the Carriere Motion Appliance and Class II Elastics: CBCT Analysis of Treatment Effects (Doctoral dissertation, Saint Louis University).

Kim-Berman, H., McNamara Jr, J.A., Lints, J.P., McMullen, C. and Franchi, L., 2019. Treatment effects of the Carriere® Motion 3D™ appliance for the correction of Class II malocclusion in adolescents. The Angle Orthodontist, 89(6), pp.839-846

Ellen, E.K., Schneider, B.J. and Sellke, T., 1998. A comparative study of anchorage in bioprogressive versus standard edgewise treatment in Class II correction with intermaxillary elastic force. American journal of orthodontics and dentofacial orthopedics, 114(4), pp.430-436.

Jones, G., Buschang, P.H., Kim, K.B. and Oliver, D.R., 2008. Class II non-extraction patients treated with the Forsus Fatigue Resistant Device versus intermaxillary elastics. The Angle Orthodontist, 78(2), pp.332-338.

Janson, G., Sathler, R., Fernandes, T.M.F., Branco, N.C.C. and de Freitas, M.R., 2013. Correction of Class II malocclusion with Class II elastics: a systematic review. American Journal of Orthodontics and Dentofacial Orthopedics, 143(3), pp.383-392.

Uzel A, Uzel I, Toroglu MS. Two different applications of Class II elastics with nonextraction segmental techniques. Angle Orthod. 2007; 77: 694– 700.

Nelson, B., Hansen, K. and Hägg, U., 2000. Class II correction in patients treated with Class II elastics and with fixed functional appliances: a comparative study. American Journal of Orthodontics and Dentofacial Orthopedics, 118(2), pp.142-149.

Barakat, D., Bakdach, W.M.M. and Youssef, M., 2021. Treatment effects of Carriere Motion Appliance on patients with Class II malocclusion: A systematic review and meta-analysis. International Orthodontics, 19(3), pp.353-364.

Contributions

Edited/contents: Farooq Ahmed

Contents: Aslam Alkadhimi