Introduction
The Carriere Motion 3D appliance (CMA) is gaining popularity for the correction of Class II dentoalveolar relationships. Recently, Gilad’s Modified Corrector (GMC), a simple, “do-it-yourself” alternative, was introduced. This study evaluated the effectiveness of the GMC in treating Class II malocclusions and compared it with the CMA.
Methods
A retrospective comparative analysis was conducted on 42 adolescent patients: 21 were treated using the GMC and 21 using the CMA. Cephalometric radiographs were taken pretreatment and after achieving a Class I posterior relationship. They were analyzed, and statistical comparisons were made between the 2 groups.
Results
Both appliances effectively corrected the Class II molar relationship. The changes were primarily dentoalveolar in nature. The maxillary first molar was distalized, tipped distally, and also derotated by the 2 appliances. Both appliances mesialized the mandibular dentition, causing minimal proclination and protrusion of the mandibular incisors. The treatment duration was comparable for both groups.
Conclusions
The GMC and CMA effectively correct Class II malocclusions probably through similar mechanisms. The GMC appliance may offer a practical alternative to the CMA.
Highlights
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Both appliances effectively correct Class II malocclusions via identical mechanisms.
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The effects are mainly dentoalveolar.
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The proportions of the contributing factors differ between the appliances.
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Essix retainers provide effective and stationary anchorage to the mandibular incisors.
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Gilad’s Modified Corrector may be an alternative to the Carriere Motion appliance.
The mesial positioning of the maxillary molars relative to the mandibular molars characterizes Class II malocclusion. , It presents a common and complex challenge in orthodontics. The treatment of this condition involves addressing both skeletal and dentoalveolar discrepancies, , with a variety of modalities available for this purpose. , Skeletal correction can be accomplished by using fixed, , or removable functional appliances, , or by a headgear. , Another approach is distalization of the maxillary molars, which can be achieved with various appliances, including headgear, Pendulum, Carriere Motion 3D appliance (CMA), , and skeletal anchorage. , In recent years, the CMA Appliance introduced by Luis Carrière in 2004, has gained popularity because of its effectiveness in correcting Class II malocclusions. ,,, The CMA is an original and innovative intraoral appliance. Its unique ball-and-socket design enables distopalatal rotation of the maxillary first molars around their palatal root, thus improving the sagittal molar relationship. , However, although the CMA has proven effective, it does have limitations, including its inability to adapt to varying canine-molar distances, potential bond failure because of a poor fit of the bonding pads to the teeth, difficulty in bonding to teeth with metal crowns or restorations, and incompatibility with bands and other orthodontic devices such as palatal expanders and transpalatal arches. Furthermore, its nonmodular design implies that component failures often necessitate the replacement of the entire fixture. These drawbacks, along with the high cost per patient of the CMA, have led to the development of other solutions. To address these limitations, Dr Gilad Har Zion introduced an alternative called Gilad’s Modified Corrector (GMC). This adaptation retains most of the fundamental principles of the CMA, while potentially addressing some of its drawbacks. The GMC consists of a section of 16 × 22-in stainless-steel archwire connected to a maxillary molar band and to a bracket on the mesial side of either the canine or the first premolar. A closed coil spring is threaded onto the archwire to maintain the distance between the teeth ( Fig 1 , A and B ). This study aimed to (1) evaluate the effectiveness of the GMC in treating Class II malocclusions, and (2) compare the mechanism of Class II correction between the GMC and the CMA.
A , GMC; B, GMC-short version.
Material and methods
This study examined the efficacy of GMC in the treatment of Class II malocclusions and compared its effectiveness to that of the CMA. To determine the sample size, a power analysis was conducted using G∗Power software (version 3.1.9.6; Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany), based on a 2-tailed t test, , with an α-level of 0.05 and aiming for 80% statistical power. The analysis indicated that a minimal sample size of 17 per group was required, 34 subjects in total. The inclusion criteria were: (1) late mixed dentition or permanent dentition at the beginning of treatment, with the maxillary permanent canines fully erupted; (2) bilateral Angle Class II with an end-to-end or larger molar discrepancy; (3) bilateral Class II canine relationship of at least half a unit; (4) the achievement of Class I molar and canine relationships successfully; (5) no prior orthodontic intervention was performed before placing the CMA or GMC; and (6) patients treated with regular versions of CMA or GMC (ie, between the maxillary canines and the maxillary first molars). Patients with syndromes, skeletal deformities, posterior crossbites, scissor bite, and unilateral use of CMA or GMC were excluded. The allocation of patients into treatment groups was conducted in a consecutive temporal manner. From a start date to an end date, patients arriving for treatment were treated with the CMA. In the subsequent period, patients received treatment with the GMC. The study was approved by the Ethics Board Committee (0346-19-RMB).
A total of 50 adolescent patients, treated by 2 orthodontic specialists, were collected (25 for the GMC group and 25 for the CMA group). The orthodontists had the same experience with both appliances and followed the same treatment protocol. A comparative analysis of cephalometric radiographs, taken at the beginning and the end of the treatment phase with a CMA or a GMC, was conducted. To match the groups in terms of gender, age, and initial sagittal and vertical cephalometric values, 4 patients with severely deviating parameters from each group were excluded from the final analysis. Therefore, the research sample is composed of 42 patients, 21 in each group.
In the CMA group, the appliance was fitted according to the manufacturer’s instructions. In the mandible, buccal tubes with hooks were bonded to the first molars. A clear retainer, fabricated of 1-mm-thick Essix A+ plastic (Sirona Dentsply, Charlotte, NC), was used in the mandibular dentition for anchorage. The elastic wear consisted of Force 1 elastics (1/4-in 6 oz) for 1 month, followed by Force 2 elastics (3/16-in 8 oz; Henry Schein Orthodontics, Carlsbad, Calif) worn until a posterior Class I molar relationship was achieved ( Fig 2 , A and B ). The elastics were stretched between the maxillary canine to the mandibular first molar. The patients were instructed to wear the elastics all the time, except during meals and tooth brushing, and to change them after every meal. In the GMC group, bands were fitted and cemented onto the maxillary first molars, using a 0.022-in slot, and conventional MBT preadjusted brackets were bonded to the canines. A segment of 16 × 22-in stainless-steel archwire was used to connect the band to the bracket on each side. This archwire was carefully bent to ensure a passive fit into the slot of the bracket on the canine. A closed coil spring was then threaded onto the archwire to maintain a constant distance between the 2 teeth. The mandibular configuration, the elastic regimen, and the locations of placement followed the same protocol as the CMA group ( Fig 2 , C and D ). A second cephalometric radiograph was taken at the end of the treatment phase with the CMA or the GMC ( Fig 2 , B and D ). All radiographs were traced by a single experienced investigator (E.K.), and the tracings were digitized using OrthoData Cephalometric Analysis software (Ramat Denya, Jerusalem, Israel). Cephalometric measurements were performed twice by the same operator to verify landmark locations. To evaluate the reliability of the measurements, 10 randomly selected cephalograms were redigitized and remeasured by the same investigator after 4 weeks. The correlation coefficients were all >0.9. Cephalometric analysis was used to assess skeletal, dental, and soft tissue parameters. The dental parameters were analyzed to evaluate the Class II correction. Figure 3 illustrates the cephalometric measurements used to assess the movement of the molars.
A and B, A 14.5-year-old male patient with a Class II Division 1 malocclusion before treatment ( A ), and after 4.5 months of treatment with a CMA, the sagittal correction was completed ( B ). C and D, A 14-year-old male patient with a Class II Division 1 malocclusion before treatment ( C ), and after 4 months of treatment with a GMC, the sagittal correction was completed ( D ).
Cephalometric measurements for evaluating molars. 1 , DU6-L6 (mm); 2 , MU6-L6 (mm); 3 , NP-U6 (mm); 4 , NP-L6 (mm); 5 , PP-U6 (°); 6 , SN-U6 (°); 7 , S-U6 (mm); 8 , S-L6 (mm).
Statistical analysis
Statistical analysis was performed using PAST software (version 4.09; Natural History Museum, University of Oslo, Norway). Information for each measurement was obtained through descriptive statistics. The normal distribution of samples was assessed using the Shapiro-Wilk test. For samples with a normal distribution, a Student’s t test was performed. For nonnormally distributed data, the Mann-Whitney test was applied. For the comparison of treatment changes within the groups, the Paired t test was used for samples with normal distribution, and the Wilcoxon signed rank test was used for samples without normal distribution. To mitigate the risk of false-positive results arising from multiple comparisons, the Holm-Bonferroni adjustment method was applied.
Results
The demographic data for the GMC and CMA groups are presented in Table I . It demonstrates the match between the 2 groups. No significant difference was found in the treatment duration between the 2 appliances (CMA: 7.3 ± 2.9 months; GMC: 8.04 ± 3.8 months). The analysis of primary values for both groups, as shown in Table II , exhibits no significant differences in any of the measurements, indicating a similarity in the initial comparative values.
Table I
Demographic data of the CMA and the GMC groups
| Characteristics | CMA (n = 21) | GMC (n = 21) | P value |
|---|---|---|---|
| Mean age (y) | 13.35 ± 1.05 | 13.33 ± 0.9 | 0.95 |
| Median age (y) | 13.5 | 13.15 | |
| Range of ages (y) | 11.2-15.2 | 12-15.1 | |
| Treatment average duration (mo) | 7.3 ± 2.9 | 8.04 ± 3.8 | 0.67 |
| Female: male | 13:8 | 13:8 |
Table II
Comparison between the initial values of the CMA and GMC groups
| Variable | CMA-PRE | GMC-PRE | P value |
|---|---|---|---|
| Maxillary skeletal, sagittal | |||
| SNA (°) | 81.81 ± 2.36 | 80.88 ± 3.41 | 0.40 |
| A-NA Vertical (mm) | 1.56 ± 3.17 | 0.98 ± 2.80 | 0.53 |
| Maxillary length (Co-A) (mm) | 87.07 ± 4.79 | 87.68 ± 5.10 | 0.69 |
| Mandibular skeletal, sagittal | |||
| SNB (°) | 76.73 ± 3.29 | 76.27 ± 3.19 | 0.64 |
| Pog-NA vertical (mm) | −4.95 ± 5.26 | −4.53 ± 5.14 | 0.82 |
| Mandibular length (Co-Gn) (mm) | 107.74 ± 6.61 | 107.98 ± 6.43 | 0.90 |
| Maxillomandibular | |||
| Wits (mm) | 3.07 ± 2.99 | 2.12 ± 2.07 | 0.72 |
| Maxillomandibular differential (mm) | 20.68 ± 4.32 | 20.31 ± 3.52 | 0.76 |
| Vertical skeletal | |||
| SN-Mp (°) | 35.55 ± 3.40 | 35.12 ± 4.47 | 0.72 |
| Facial height ratio L∖T (%) | 52.82 ± 2.40 | 53.52 ± 2.08 | 0.16 |
| Dentoalveolar incisors | |||
| U1 to SN (°) | 103.36 ± 7.09 | 104.33 ± 6.57 | 0.65 |
| U1 to A-Pog (mm) | 6.72 ± 2.11 | 6.92 ± 2.01 | 0.75 |
| L1-Mp (°) | 96.89 ± 5.81 | 96.69 ± 5.98 | 0.91 |
| L1 to A-Pog, (mm) | 1.27 ± 1.53 | 1.38 ± 1.35 | 0.81 |
| Incisor overjet (mm) | 4.88 ± 2.07 | 5.15 ± 1.63 | 0.40 |
| Incisor overbite (mm) | 3.89 ± 2.09 | 3.53 ± 1.92 | 0.39 |
| Dentoalveolar molars | |||
| DU6-L6, (mm) | 1.07 ± 2.25 | 0.12 ± 2.24 | 0.23 |
| MU6-L6 (mm) | 0.64 ± 1.61 | −0.40 ± 2.30 | 0.19 |
| NP-U6 (mm) | 25.45 ± 4.63 | 26.67 ± 3.72 | 0.35 |
| NP-L6 (mm) | 26.10 ± 4.14 | 26.67 ± 3.31 | 0.62 |
| Derotation (mm) | 0.42 ± 0.19 | 0.15 ± 1.10 | 0.57 |
| SN-U6 Angle (°) | 106.43 ± 4.90 | 106.20 ± 4.62 | 0.88 |
| S-U6 (mm) | −60.96 ± 6.03 | −60.17 ± 3.45 | 0.61 |
| S-L6 (mm) | −60.86 ± 5.85 | −60.15 ± 3.31 | 0.63 |
| Soft tissue | |||
| Gl’-Sn’-Pog’ (°) | 18.28 ± 6.01 | 18.89 ± 5.71 | 0.74 |
| Nasolabial (°) | 98.39 ± 9.85 | 98.72 ± 7.84 | 0.90 |
| Upper lip protrusion (mm) | −2.85 ± 2.06 | −1.80 ± 2.98 | 0.19 |
| Lower lip protrusion (mm) | −0.44 ± 2.68 | −0.19 ± 3.27 | 0.79 |
| Upper 1 exposure (mm) | 5.30 ± 1.67 | 4.18 ± 2.04 | 0.06 |
Note. Values are presented as mean ± standard deviation.
PRE, pretreatment.
Comparison of treatment effects within the CMA group
The only significant change in the skeletal parameters induced by CMA was the Wits appraisal, which demonstrated a significant decrease of 1.73 ± 1.97 mm ( Table III ). Dentally, the CMA treatment resulted in a significant protrusion of the mandibular incisors of 1.88 ± 1.36 mm measured to the A-Pog line, and a nonsignificant proclination of 2.01° ± 4.21° relative to the mandibular plane ( Table III ). The overjet and overbite were significantly reduced by 1.66 ± 1.18 mm and 1.75 ± 1.35 mm, respectively ( Table III ). The anteroposterior relation of maxillary and mandibular molars significantly improved in the distal (DU6-L6: 3.63 ± 2.62 mm) and the mesial aspects (MU6-L6: 4.38 ± 1.4 mm) as well ( Table III ). Our results demonstrated a significant maxillary molar distalization (NP-U6) of 2.74 ± 2.36 mm, and a significant mandibular molar mesialization (NP-L6) of 1.73 ± 2.17 mm ( Table III ). The results also indicated a significant increase in distal tipping of the maxillary molar of 5.61° ± 4.62 relative to SN ( Table III ). No significant vertical changes in the maxillary and mandibular first molars were observed. The CMA did not significantly affect the soft tissue parameters ( Table III ).
Table III
Comparison of the treatment effects within the CMA group
| Variable | CMA-PRE | CMA-POST | Difference | P value |
|---|---|---|---|---|
| Maxillary skeletal, sagittal | ||||
| SNA (°) | 81.81 ± 2.36 | 81.20 ± 1.75 | −0.61 ± 1.90 | 0.08 |
| A-NA vertical (mm) | 1.56 ± 3.17 | 0.85 ± 2.59 | −0.72 ± 1.93 | 0.10 |
| Maxillary length (Co-A) (mm) | 87.07 ± 4.79 | 86.98 ± 4.50 | −0.08 ± 3.48 | 0.90 |
| Mandibular skeletal, sagittal | ||||
| SNB (°) | 76.73 ± 3.29 | 76.96 ± 2.50 | 0.23 ± 1.51 | 0.44 |
| Pog-NA vertical (mm) | −4.95 ± 5.26 | −4.96 ± 4.69 | −0.01 ± 3.87 | 0.99 |
| Mandibular length (Co-Gn) (mm) | 107.74 ± 6.61 | 109.13 ± 6.79 | 1.39 ± 5.01 | 0.22 |
| Maxillomandibular | ||||
| Wits (mm) | 3.07 ± 2.99 | 1.34 ± 2.23 | −1.73 ± 1.97 | 0.002 |
| Maxillomandibular differential (mm) | 20.68 ± 4.32 | 22.14 ± 4.49 | 1.46 ± 2.53 | 0.02 |
| Vertical skeletal | ||||
| SN-Mp (°) | 35.55 ± 3.40 | 36.09 ± 4.49 | 0.54 ± 2.56 | 0.35 |
| Facial height ratio L∖T (%) | 52.82 ± 2.40 | 53.25 ± 2.33 | 0.43 ± 1.25 | 0.19 |
| Dentoalveolar incisors | ||||
| U1-SN (°) | 103.36 ± 7.09 | 104.15 ± 5.82 | 0.80 ± 3.59 | 0.32 |
| U1 to A-Pog (mm) | 6.72 ± 2.11 | 6.67 ± 1.55 | −0.05 ± 1.08 | 0.84 |
| L1-Mp (°) | 96.89 ± 5.81 | 98.90 ± 4.47 | 2.01 ± 4.21 | 0.04 |
| L1 to A-Pog, (mm) | 1.27 ± 1.53 | 3.15 ± 1.78 | 1.88 ± 1.36 | <0.001 |
| Incisor overjet (mm) | 4.88 ± 2.07 | 3.22 ± 1.66 | −1.66 ± 1.18 | <0.001 |
| Incisor overbite (mm) | 3.89 ± 2.09 | 2.14 ± 2.16 | −1.75 ± 1.35 | <0.001 |
| Dentoalveolar molars | ||||
| DU6-L6 (mm) | 1.07 ± 2.25 | −2.56 ± 1.28 | −3.63 ± 2.62 | <0.001 |
| MU6-L6 (mm) | 0.64 ± 1.61 | −3.73 ± 0.91 | −4.38 ± 1.40 | <0.001 |
| NP-U6 (mm) | 25.45 ± 4.63 | 28.20 ± 3.82 | 2.74 ± 2.36 | <0.001 |
| NP-L6 (mm) | 26.10 ± 4.14 | 24.37 ± 3.59 | −1.73 ± 2.17 | 0.002 |
| Derotation (mm) | 0.42 ± 0.19 | 1.17 ± 1.46 | 0.75 ± 1.61 | 0.08 |
| SN-U6 angle (°) | 106.43 ± 4.90 | 112.04 ± 5.86 | 5.61 ± 4.62 | <0.001 |
| S-U6 (mm) | −60.96 ± 6.03 | −61.19 ± 4.96 | −0.23 ± 2.89 | 0.72 |
| S-L6 (mm) | −60.86 ± 5.85 | −61.79 ± 4.92 | −0.93 ± 2.89 | 0.16 |
| Soft tissue | ||||
| Gl’-Sn’-Pog’ (°) | 18.28 ± 6.01 | 16.64 ± 5.70 | −1.64 ± 4.57 | 0.16 |
| Nasolabial (°) | 98.39 ± 9.85 | 100.50 ± 10.15 | 2.11 ± 9.85 | 0.34 |
| Upper lip protrusion (mm) | −2.85 ± 2.06 | −3.92 ± 2.58 | −1.07 ± 2.85 | 0.10 |
| Lower lip protrusion (mm) | −0.44 ± 2.68 | −1.04 ± 3.68 | −0.60 ± 3.60 | 0.46 |
| Upper 1 exposure (mm) | 5.30 ± 1.67 | 5.34 ± 3.40 | 0.04 ± 2.92 | 0.95 |
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