Skeletal and dental changes with treatment of non- growing class II malocclusions with Carriere appliance: A cephalometric study

Objectives: This retrospective study aimed to assess the skeletal and dental effects of the Carriere ® motion 3D ™ appliance (CMA) followed by comprehensive orthodontic treatment in Chinese adult patients with Class II malocclusions. Material and Methods: The sample size consisted of 25 post-pubertal patients treated with CMA, followed by comprehensive orthodontic therapy with fixed appliances ( n = 5) or clear aligners ( n = 20). Lateral cephalometric radiographs were collected at 3 time points: Pre-treatment (T1), immediately after Class II correction with the CMA (T2), and immediately after completion of comprehensive orthodontic therapy (T3). Changes between the time points were evaluated using a matched paired t-test. Intra-rater reliability was evaluated with Pearson correlation coefficients. Inter-rater reliability was assessed with an intra-class correlation coefficient. Results: The average treatment time with the CMA was 6.3 ± 1.9 months. The total treatment time together with comprehensive orthodontic therapy was 32.2 ± 6.5 months. During CMA treatment, dentoalveolar movements accounted for 84% of molar correction and 77% of overjet reduction. CMA significantly corrected the overjet by 1.6 mm and molar relationship by 3.1 mm. Dentoalveolar treatment effects of the CMA included 2.2 mm distalization of maxillary molars, 1.6 mm mesialization and 0.7 mm extrusion of mandibular molars, 1.5° retroclination of the maxillary incisors, 5.0° proclination of mandibular incisors, and 2.4° steepening of the occlusal plane. Minor skeletal changes were observed, including a 0.4° decrease in SNB, 0.3° increase in ANB, and 0.6° increase in mandibular plane angle; however, these changes were not clinically significant. Following comprehensive treatment, total overjet correction was 2.5 mm. Molar relationship partially relapsed after CMA removal, with 2.2 mm total correction. Some overbite reduction and mandibular incisor proclination also rebounded. Total angular changes post-treatment included 6.5° retroclination of the maxillary incisors and 2.7° proclination of the mandibular incisors. Conclusion: CMA appliances can effectively improve molar relationships and reduce overjet in adult Class II patients through primarily dentoalveolar movements. The change in molar relationship suggests that CMA may best be used for adult Class II malocclusions that require 2–3 mm of molar correction.