Changes in masseter muscle morphology after surgical-orthodontic treatment in skeletal Class III patients with mandibular asymmetry: the automatic masseter muscle segmentation model

Introduction: This study evaluated the masseter muscle changes after surgical-orthodontic treatment in skeletal Class III patients using automatic segmentation. Methods: Images of 120 skeletal Class III malocclusion patients were obtained and reconstructed at T0 (pre-treatment), T1 (preoperative), and T2 (6–12 months postoperative). The patients were divided into symmetrical and asymmetrical groups. The volume, major axis length, maximum cross-sectional area (CSAM), horizontal cross-sectional area 5 mm above the mandibular foramen (CSAF), and orientation were calculated automatically. Results: In the asymmetrical group, the volume and major axis length on the deviated side were lesser than on the non-deviated side at T0, T1, and T2 (p < 0.05). There were no significant differences in CSAM and CSAF bilaterally. The orientation was coronally more vertical and sagittally more forward on the deviated side (both p < 0.001). In the symmetrical group, there were no significant bilateral differences at T0, T1, and T2. The volume, major axis length, and CSAF decreased, and the coronal orientation was more vertical on the non-deviated side at T2 compared to T0 in both groups (p < 0.05). The coronal plane orientation was more inclined on the deviated side at T2 compared to T0 in the asymmetrical group (p < 0.05). Conclusions: The smaller volume on the deviated side at T2 indicates the need for myofunctional training after surgery. The masseter muscle volume and cross-sectional area did not recover to the pre-orthodontic levels. Studies with longer follow-up durations are needed to confirm these findings.引言：本研究采用自动分割（automatic segmentation）技术，评估骨性Ⅲ类错𬌗患者接受正畸正颌联合治疗后咬肌的变化情况。 方法：本研究纳入120例骨性Ⅲ类错𬌗患者的影像数据，分别于T0（治疗前）、T1（术前）及T2（术后6~12个月）三个时间点进行影像重建。将患者分为对称性分组与非对称性分组，自动计算咬肌的体积、长轴长度、最大横截面积（maximum cross-sectional area, CSAM）、下颌孔上方5mm处的水平横截面积（horizontal cross-sectional area 5 mm above the mandibular foramen, CSAF）以及肌纤维走向。 结果：在非对称性分组中，T0、T1及T2三个时间点，偏斜侧咬肌的体积与长轴长度均小于非偏斜侧（p<0.05）。双侧咬肌的最大横截面积与下颌孔上方5mm处的水平横截面积无显著差异。偏斜侧的肌纤维走向在冠状面上更趋于垂直，在矢状面上更靠前（两组p值均<0.001）。在对称性分组中，T0、T1及T2三个时间点双侧咬肌各指标均无显著差异。两组患者在T2时间点的咬肌体积、长轴长度及下颌孔上方5mm处的水平横截面积均较T0时间点下降，且非偏斜侧的冠状面肌纤维走向更趋于垂直（p<0.05）。非对称性分组患者在T2时间点的偏斜侧冠状面肌纤维走向较T0时间点更倾斜（p<0.05）。 结论：T2时间点偏斜侧咬肌体积更小，提示术后需开展肌功能训练。咬肌体积与横截面积未恢复至正畸治疗前水平。未来需开展更长随访周期的研究以验证本研究结论。

搜集汇总

背景与挑战

背景概述

该数据集聚焦于骨骼III类伴下颌不对称患者手术正畸治疗后咬肌形态的变化，通过自动分割模型分析120名患者的图像数据，比较对称和非对称组在治疗不同阶段的体积、长度和横截面积等参数。研究发现非对称组偏斜侧咬肌体积较小且方向存在差异，术后咬肌体积和横截面积未完全恢复，提示术后需肌功能训练，并强调了长期随访的重要性。数据集以XLSX格式提供，由北京大学口腔医学院研究团队发布，适用于正畸学领域的研究。