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Cephalometric analysis of dental and skeletal effects of Carriere Motion 3D appliance for Class II malocclusion

Cephalometric analysis of dental and skeletal effects of Carriere Motion 3D appliance for Class II malocclusion



American Journal of Orthodontics and Dentofacial Orthopedics, 2022-05-01, Volume 161, Issue 5, Pages 659-665, Copyright © 2021 American Association of Orthodontists


Introduction

The objective was to describe the dental and skeletal changes obtained using the Carriere Motion Appliance (CMA), lateral cephalogram, and the corresponding cephalometric tracings.

Methods

A sample of 29 patients with Class II malocclusion (mean age, 12.6 ± 1.7 years) was retrospectively selected. All patients were treated at a single center using a CMA as the primary sagittal correction device. Cephalometric tracings at the beginning and end of treatment were compared. Each cephalometric tracing was performed 3 times by the same operator.

Results

Using the CMA, the 29 patients studied reached dental Class I in 4.4 ± 0.98 months. All measurements were subjected to statistical analysis, paired t test, and all displayed differences between T0 and T1 ( P <0.05) except for the SNA. At the end of treatment, the Wits and ANB values were reduced by 1.38 mm and 0.8°, respectively. Overbite and overjet were also reduced by 1.4 mm and 2 mm, respectively. The SNB, FMA, LAFH, and IMPA increased to a lesser extent (ie, 0.7°, 0.4°, 1.5 mm, and 1.5°, respectively).

Conclusions

The CMA is a rapid and efficient means of correcting Class II malocclusion. Its effects are predominantly dentoalveolar, with minimal skeletal alteration of little clinical significance.

Highlights

  • Carriere Motion Appliance (CMA) was used to obtain a super Class I molar relationship.

  • The effects of CMA are due to dentoalveolar changes, with minimal effect of skeletal change.

  • Six oz elastics provided a similarly rapid Class II correction as 8 oz elastics.

  • In patients with retroclination of maxillary incisors, there is proper dental correction.

Class II malocclusion was first described by Edward Angle as a more distal position of the mandibular dentition than the maxillary; there are 2 types, Division 1 and 2, and it is still today a topic of much study and discussion that covers many aspects, including diagnosis, treatment plan and timing. Class II malocclusion is the product of the combination of several dentoalveolar and skeletal factors, among which the most common is mandibular retrusion; these factors must be weighed in the choice of treatment plan.

There are many devices for the treatment of Class II malocclusion; some influence skeletal growth, whereas others have a prevalent dentoalveolar action. The former group includes functional, fixed and removable appliances, whereas the latter features fixed appliances with intermaxillary elastics and molar distalization devices, some of which are also combined with temporary skeletal anchorage. Depending on the type of discrepancy, extractions in 1 or both arches, or orthognathic surgery may also be indicated.

A recent introduction to the range of devices used for Class II correction is the Carriere Motion Appliance (CMA); this is a device consisting of an arm; a pad to be cemented to either the canine or the first premolar, equipped with a hook for applying an elastic; and another pad to be cemented to the first molar. The latter pad features a ball and socket-type structure that allows derotation of the maxillary first molar while controlling its inclination during the correction of the posterior teeth as a single unit ( Fig 1 ). In the mandibular arch, a tube or button is cemented onto the mandibular first or second molar to apply the elastic. Various methods can be used to control the proclination of the mandibular incisors, including lingual archwire, miniscrews, or a thermoformed Essix-type retainer. The Essix also has the added advantage of causing mandibular disclusion.

Carriere Motion Appliance in detail. A, CMA; B, canine pad with elastic hook; C, lateral view of the molar pad; and D, molar pad.
Fig 1
Carriere Motion Appliance in detail. A, CMA; B, canine pad with elastic hook; C, lateral view of the molar pad; and D, molar pad.

The CMA can be used in patients with unilateral or bilateral Class II, Division 1 or 2, in both growing and adult patients. One of the main advantages of the device is that it can be used to correct Class II before beginning treatment with fixed orthodontics or aligners, at a favorable moment for patient compliance.

We aimed to investigate the dental and skeletal changes achieved using the CMA via lateral cephalograms and cephalometric analysis.

Material and methods

From the archive of the University of Ferrara Postgraduate School of Orthodontics, the records of all patients with Class II malocclusion treated using CMA from 2017 to 2019 were selected by a single operator (S.G.A.). The selection took place according to the following inclusion criteria: (1) Class II malocclusion classified from edge-to-edge to full, (2) aged between 10 and 14 years, (3) hypodivergent or normodivergent skeletal pattern, and (4) the availability of full pretreatment (T0) records (intraoral and extraoral photographs, panoramic radiograph, lateral cephalogram, digital models with 3 Shape TRIOS [3Shape, Copenhagen, Denmark]) and posttreatment (T1 at CMA removal) records (intraoral and extraoral photographs, panoramic radiograph, lateral cephalogram, digital models with 3 Shape TRIOS). The final sample was thus composed of 29 consecutive patients (12 males and 17 females), with an average age of 12.62 ± 1.77 years.

All patients were treated using the same protocol: CMA; lower Essix; and 6¼ oz elastics, to be changed 3 times a day and removed only during meals; together with the thermoformed retainer ( Fig 2 ).

A and B , Intraoral photographs before CMA treatment; C and D , posttreatment intraoral photographs with CMA still in situ.
Fig 2
A and B , Intraoral photographs before CMA treatment; C and D , posttreatment intraoral photographs with CMA still in situ.

Each T0 and T1 lateral cephalogram was obtained from the same machine and was analyzed by orienting it so that the Frankfurt plane was parallel to the floor, with the same magnification factor, and the cephalometric measurements were performed 3 times by the same operator and on 3 different computers using Dolphin Imaging Software (Dolphin Imaging and Management Solutions, Chatsworth, Calif).

The cephalometric values analyzed are shown in Table I .

Table I
Cephalometric measurements
Variables Definition
SNA The angle between the SN plane and NA line
SNB The angle between the SN plane and NB line
ANB The angle between NA and NB lines
FMA The angle between the mandibular plane and the Frankfurt plane
IMPA The angle between the mandibular plane and the axis of the inferior anterior incisor
U1-palatal plane (PP) The angle between the axis of the maxillary anterior incisor and the palatal plane (anterior and posterior nasal spines)
Mandibular plane angle The angle between the mandibular plane (Gonion-Gnathion) and the Frankfurt plane
Occlusal plane angle The angle between the occlusal plane and the mandibular incisor
Wits AO-BO segment in which AO and BO indicate the projections of A and B points on the occlusal plane
Overjet Distance between incisal point of maxillary incisor and incisal point of mandibular incisor taken on a plane parallel to the palatal one
Overbite Distance between incisal point of maxillary incisor and incisal point of mandibular incisor taken on a plane perpendicular to the palatal one
Midfacial length (Co-A) Distance between condilyon and point A
Mandibular length (Co-Gn) Distance between condylion and point B
Low anterior facial height LAFH (ANS-Me) Distance between anterior nasal spine and menton
PTV-6 Distance between the maxillary first molar and pterygovertical line
Mandibular plane-occlusal plane Distance between occlusal plane and mandibular plane

Statistical analysis

A sample of 29 subjects was used to assess whether some measures statistically differ between pretreatment and posttreatment. Different outcomes were measured 3 times (including T0 and T1). A paired sample t test was used to assess the difference between the pretreatment and posttreatment.

R statistical software (version 2019; R Core Team, Vienna, Austria) was used to perform the statistical analysis. Given the actual sample size, the desired power of



1





β


=


0.80


and a significance level of



α


=


0.05


, the experiment would be able to detect an effect size equal to



d


z


=


0.4733078


that lies between the small and moderate thresholds (0.2-0.5) according to Sawiloski.

The assessment of measurement error (in terms of repeatability) was estimated using the intraclass correlation (ICC) index. All outcomes’ ICC index is estimated above 0.94, indicating excellent repeatability of the experiment for all outcomes.

Results

A super Class I relationship was achieved in all patients, and the average duration of CMA treatment was 4.4 ± 0.94 months (with a minimum and maximum treatment time of 3 and 6 months, respectively). All study values were obtained from cephalometric tracings performed digitally on T0 and T1 lateral cephalograms. Each tracing was performed 3 times by the same operator using Dolphin software. The resulting measurements were reported on an Excel sheet and then statistically analyzed.

Table II shows that all the cephalometric parameters analyzed significantly changed with the exception of the SNA angle, which showed no statistically significant variation. In particular, there were statistically significant sagittal mandibular alterations, with an average increase in T1 values of 0.7° for SNB and 1.9 mm for Co-Gn. Furthermore, intermaxillary sagittal measures vary considerably in favor of Class recovery, specifically the Wits and ANB, which decreased respectively by an average of 1.38 mm and 0.8° ( Fig 3 ). Furthermore, the overjet and overbite decreased by 2 mm and 1.4 mm on average ( Fig 3 ). There was also a slight increase in the IMPA (which increased on average by 1.5°) ( Fig 3 ), an adverse effect of the use of elastics, although countered by the Essix retainer.

Table II
Statistically significant differences in cephalometric measurements between T0 and T1
Variables T0 T1 t df P
SNA 80.40 ± 4.718 80.42 ± 4.759 −0.16 28 0.9
SNB 76.30 ± 3.814 77.05 ± 3.838 −3.9 28 <0.001
ANB 4.457 ± 1.872 3.680 ± 1.833 8.3 28 <0.001
Wits 2.947 ± 1.959 1.564 ± 1.395 5.3 28 <0.001
FMA 20.06 ± 5.115 20.54 ± 5.306 −2 28 0.06
U1-palatal plane 110.4 ± 8.085 111.2 ± 8.184 −4.2 28 0.0003
IMPA 99.85 ± 6.320 101.40 ± 6.013 −6.4 28 <0.001
OVJ 5.601 ± 1.869 3.631 ± 1.686 6.7 20 <0.001
OVB 3.814 ± 1.483 2.441 ± 1.672 7.1 28 <0.001
Midfacial length 79.63 ± 6.027 80.91 ± 5.668 −2.7 28 0.01
Mandibular lenght 100.3 ± 7.795 102.7 ± 7.939 −4.6 28 <0.001
Mandibular plane angle 17.51 ± 4.691 18.32 ± 5.029 −3.8 28 0.0008
LAFH 55.73 ± 6.127 57.24 ± 6.239 −4.3 28 0.0002
Occlusal plane 65.86 ± 6.288 67.61 ± 6.385 −8.5 28 <0.001
PTV-U6 14.85 ± 3.024 14.25 ± 3.219 1.7 28 0.1
Mandibular plane-occlusal plane 13.86 ± 4.470 12.77 ± 4.807 3.3 28 0.002
Note. Values are mean ± standard deviation. All values between T0 and T1 are significantly different ( P <0.05) (excluding SNA angle, P <0.90).
df , degrees of freedom.

Diagrams showing statistically significant reduction of overjet, overbite, and Witts index and increase of IMPA and U1-PP.
Fig 3
Diagrams showing statistically significant reduction of overjet, overbite, and Witts index and increase of IMPA and U1-PP.

For each outcome, the following information will be reported: (1) descriptive statistics by time ( Table II ), (2) bivariate plot (mean ± standard deviation, split by time), and (3) t test log results ( Table II ), In addition, Table III reports on ICC measures of all outcomes for repeatability analysis. ( Table III ).

Table III
ICC Index by outcomes
Variable ICC
Wits 0.973
SNA 0.966
Overbite 0.977
U1_palatal_plane 0.998
ANB 0.945
IMPA 0.997
SNB 0.941
Mandibular plane-occlusal plane 0.996
FMA 0.996
occlusal_plane angle 0.997
LAFH 0.997
Mandibular plane angle 0.996
Overjet 0.982
Mandibular_length 0.993
Midfacial_length 0.985
PTV-6 0.993

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