Department of Maxillofacial Orthognathics, Division of Maxillofacial and Neck Reconstruction, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Japan.
Eur J Orthod. 2022 May 24;44(3):294-302. doi: 10.1093/ejo/cjab060.
Understanding the mechanism of mandibular asymmetry (MA) is important to provide suggestions for occlusal treatment and to know the developmental process of masticatory dysfunction. To investigate the morphological and functional effects on MA, we evaluated the three-dimensional position of the glenoid fossa and its relationship to asymmetrical condylar translational movement.
In this retrospective study, 50 subjects who previously underwent computed tomography for surgical purposes were divided into MA and control groups according to a menton deviation of at least 4 mm from the mid-sagittal plane. The glenoid fossae positions were evaluated using a three-dimensional analysis program. Condylar translational movements were recorded and measured by computerized axiography on protrusion. Side-to-side asymmetry was measured for each parameter. Asymmetry index value was calculated to assess the correlation between glenoid fossa position and condylar movement. Wilcoxon's signed-ranked test, Mann-Whitney U-test, and Spearman's rank correlation were used for the statistical analysis.
In the MA group, glenoid fossa position on the shifted side was significantly inferior and posterior as compared to that on the non-shifted side and of the control group. Condylar path length and sagittal condylar inclination were significantly greater on the shifted side versus non-shifted side, while no significant difference was found in transverse condylar inclination. The asymmetry index of the anterior-posterior glenoid fossa position was significantly correlated with that of condylar path length and bilateral transverse condylar inclination. In the control group, there were no significant correlations among the morphological and functional parameters.
This study did not consider muscle activity and disc position, which may affect condylar movement.
Functional asymmetry of condylar translational movements is closely related to asymmetry of glenoid fossa position in MA patients.
了解下颌偏斜（MA）的发病机制对于咬合治疗具有重要意义，有助于了解咀嚼功能障碍的发育过程。为了研究 MA 的形态和功能影响，我们评估了关节窝的三维位置及其与不对称髁突平移运动的关系。
本回顾性研究根据下颌颏部偏移是否至少为中矢状面的 4mm 将 50 例因手术而行 CT 检查的患者分为 MA 组和对照组。使用三维分析程序评估关节窝位置。通过计算机轴位记录和测量前伸时髁突的平移运动，并测量每个参数的侧向不对称。计算偏斜指数值以评估关节窝位置与髁突运动之间的相关性。采用 Wilcoxon 符号秩检验、Mann-Whitney U 检验和 Spearman 秩相关分析进行统计学分析。
在 MA 组中，与非移位侧和对照组相比，移位侧的关节窝位置明显更低且更靠后。与非移位侧相比，移位侧的髁突路径长度和矢状位髁突倾斜度显著更大，而横向髁突倾斜度无显著差异。前-后向关节窝位置的不对称指数与髁突路径长度和双侧横向髁突倾斜度的不对称指数显著相关。在对照组中，形态和功能参数之间无显著相关性。
本研究未考虑可能影响髁突运动的肌肉活动和关节盘位置。
MA 患者的髁突平移运动功能不对称与关节窝位置的不对称密切相关。
