偏突颌患者颞下颌关节盘冠状向位置的MRI评估

目的研究偏突颌畸形患者双侧颞下颌关节盘-髁突位置在冠状位磁共振图像(magnetic resonance imaging,MRI)上的差异,并分析其关节盘移位程度与偏斜严重程度的相关性。方法对54例骨性Ⅲ类错患者进行标准化临床影像学检查得到闭口斜冠状位MRI,通过计算机软件测量分析其冠状位关节盘内外侧移位情况,应用wilcoxon秩和检验分析各组间颞下颌关节盘-髁位置在冠状位磁共振图像上的差异。结果40例偏突颌畸形患者中,偏斜侧7侧(17.5%)关节盘外侧移位,16侧(40.0%)内侧移位;而40侧偏斜对侧关节盘中,27侧(67.5%)关节盘内侧移位,仅2侧(5.0%)关节盘向外侧移位。14例(28侧)无偏斜骨性Ⅲ类患者中,18侧(64.3%)存在关节盘内侧移位,未发现外侧移位的关节盘。本研究证实了偏斜侧关节盘内外侧位置与偏斜对侧及无偏斜组存在显著性差异(P<0.05),中等到重度偏突颌患者偏斜侧关节盘位置与轻度及无偏斜者之间的差异具有统计学意义(P<0.05)。结论在冠状位磁共振图像中显示,中等到重度偏突颌患者偏斜侧关节盘倾向于向外侧移位,偏斜对侧关节盘倾向于向内侧移位。

Temporomandibular joint disk position assessed at coronal MR imaging in asymmetrical prognathism patients

Objective To investigate the relationship between the position of the temporomandibular joint （TMJ） disk and the condyle by using coronal magnetic resonance （MR） imaging in asymmetrical prognathism patients and the relationship between the degree of displacement and the severity of asymmetry. Methods Fifty-four patients with skeletal class Ⅲ malocclusion （40 asymmetric patients and 14 symmetric ones） had taken standardized clinical examinations. Afterward,coronal oblique MR images were acquired. The patients were divided into four grades：mild asymmetry,moderate asymmetry,severe asymmetry and symmetry. The coronal oblique images were analyzed by using computer software. The medial and lateral edges of both the TMJ disk and the condyle were marked for these imaging examinations. To eliminate the effects of different magnifications and/or distortions,the image size was standardized,and the distance between these points was measured automatically and divided by the largest mediolateral dimensions of the condyle. To assess the accuracy of the measurements,each image was measured three times. To assess the changes in position of the disk in the coronal plane in the closed positions,the Spearman test was used.Results Analyses of the coronal closed-mouth disk position revealed a lateral position of the TMJ disk relative to the condyle in 7 （17.5%） of 40 analyzed shifted side joints,and a medial location of the disk was 16 （40.0%） of 40 shifted side joints. While in the contralateral side,there was only two laterally located disks but 27 （67.5%） of 40 joints were medially located. In contrast,the medial location of the disk in both sides of the skeletal class Ⅲ symmetric patients was similar to the latter：18 （64.3%） of 28 joints exhibited a medial position of the disk relative to the condyle in this plane. These different positions of the disk between the shifted side and contralateral side,the shifted side and the control side,were both statistically significant （P〈0.05）. In the