无症状颞下颌关节盘前移位个体的动态磁共振及髁突运动轨迹特点

目的 颞下颌关节盘早期的前移位临床上可无弹响症状，了解无症状颞下颌关节盘的早期移位个体的髁突运动中心轨迹特点，将有助于早期发现隐匿性颞下颌关节结构内紊乱疾病。 方法 动态磁共振(Cine-MRI) 和ARCUSdigma系统检查30例无症状个体开闭口过程中髁状突-关节盘运动特点和下颌运动范围。 结果 Cine-MRI显示30例无症状人群中，20例健康颞下颌关节、10例单侧可复性关节盘前移位，闭口位关节盘本体部仍呈双凹形、盘后区均有轻度增厚和前移位，盘-突关系在小开口（<2 cm）期恢复正常；无症状可复性关节盘的运动中心轨迹出现弹跳切迹和偏摆，光滑性、重复性及双侧运动中心轨迹的对称性不及健康人，但是切点运动轨迹平滑，与健康人的切点运动轨迹基本一致；运动轴在髁突轨迹弹跳时出现偏斜，然后保持平行，呈现开闭口初、末时密度比开闭口中时大；髁突运动中心运动距离（13.6±3.7）mm，下颌切点运动距离（40.5±3.4）mm。 结论 髁突运动轨迹能间接反映髁突-关节盘复合体在开闭口运动中的位置变化，为下一步临床使用下颌运动轨迹仪作为早期关节盘移位的诊断提供一定的理论参考。

Characteristics of Cine-MRI and condylar movement trajectory of asymptomatic subjects with anterior disc displacement of temporomandibular joint

Objective The initial anterior disc displacement with reduction of temporomandibular joint can be asymptomatic, however the condylar movement trajectory can help early detection of occult temporomandibular joint internal disorders. Methods Appling Cine-MRI and ARCUSdigma system to investigate 30 asymptom temporomandibular joints in open-close movement. Results Ten anterior displacement discs were detected in some asymptom temporomandibular joints, temporomandibular joint discs showed biconcave shape in anterior displacement disc with reduction (ADDwR) individuals, but slightly thickness and anterior displacement, disc-condyle position returned to normal during small opening (<2 cm); In the group of anterior disc displacement with reduction without any symptom, the condyle tracking was found bounce, inflexion and asymmetry and some of incisor tracking were smooth and superposition and others showed segregated curves; The range of opening movement and maximal value of condylar movement and incisor movement respectively were (13.6±3.7) mm and (40.5±3.4) mm respectively. Conclusion The condylar movement trajectory could indirectly detect the changes of shapes and position of articular disc of temporomandibular joint during opening movement, which is helpful to diagnosis early ADDwR without symptom.