Association between bone morphology and sagittal disc position in temporomandibular joints of patients with anterior disc displacement

Abstract

Objectives: To analyze the association between sagittal temporomandibular joint (TMJ) disc position of patients with anterior disc displacement evaluated by magnetic resonance imaging (MRI) and bone morphology of the TMJ evaluated by cone-beam computed tomography (CBCT).

Methods: One hundred and seventy-eight TMJs of 97 patients were retrospectively analyzed. The TMJ disc position was evaluated using MRI and classified into four types: control group (without disc displacement), slight group (disc slightly anteriorly displaced), moderate group (disc moderately anteriorly displaced), and severe group (disc severely anteriorly displaced). The measurements of TMJ bone morphology among four groups were evaluated by CBCT through Mimics software including condyle linear dimensions (condyle length, width, and height), condylar volume and surface area, and the depth and length of the glenoid fossa, joint anterior space, joint superior space, and joint posterior space. The sagittal plane position of the condyle was also assessed. The differences in all the morphologic measurement parameters among the four groups were detected using the one-way analysis of variance or the Kruskal Wallis test, and Chi-square tests. The correlations between disc sagittal position and all the morphologic measurements were also analyzed.

Results: There were significant differences in measurements of condyle linear dimensions, condylar volume and surface area, depth of the glenoid fossa, joint spaces, and distribution of the condyle sagittal positions among the four groups. By contrast, there were no statistical differences in terms of the length of the glenoid fossa among the four groups. Correlation analysis revealed that there is a statistically significant negative correlation among condyle linear dimensions, condylar volume and surface area, the depth of the glenoid fossa, joint superior space, and disc position. However, joint posterior space was positively correlated with disc position.

Conclusions: A statistically significant correlation was determined between TMJ bone morphology and different sagittal disc positions. Degenerative changes in TMJ bone morphology clinically diagnosed should be altered, which can be the patients' marker of anterior disc displacement.

Keywords: anterior disc displacement; cone beam CT; magnetic resonance ima-ging; morphologic measurement; sagittal position; temporomandibular joint.

图 1. 根据矢状向MRI上关节盘位置进行的分组示意图

Fig 1 Diagram of classification according to the disc positions evaluated by sagittal MRI A：对照组；B：轻度组；C：中度组；D：重度组。

图 2. TMJ骨形态测量演示图

Fig 2 Schematic measurement of bone morphological parameters of the TMJ A：轴面髁突宽度、长度测量；B：矢状面关节窝长度、深度及关节结节倾斜角测量；C：矢状面关节前、上、后间隙测量；D：髁突上界；E：髁突下界；F：矢状面髁突高度测量；G：重建的髁突。