Morneburg T, Pröschel P A
University Dental Clinic, Department of Prosthodontics, Friedrich-Alexander University of Erlangen-Nürnberg, Germany.
Int J Prosthodont. 1998 Jul-Aug;11(4):317-24.
Recent research revealed that traces of single posterior reference points can depend on the location of the monitored point. The aim of this study was to quantify this dependence and to point out its consequences for clinical application of condylar path registrations.
In 60 asymptomatic volunteers, mandibular motion was recorded during protrusion, lateral excursion, and opening-closing of the jaw. Simultaneous trace-patterns of 10 condylar points including the hinge-axis point and the kinematic-axis point were compared with respect to length, inclination angles, coordination, and shape.
In protrusion, traces of the different condylar points were equal and independent of the location of the monitored point. Bennett angles depended on the sagittal position of the reference point and varied by 0.8 degree per 1 mm change of location. Opening-closing traces differed considerably. Their lengths varied by up to 9 mm and inclination angles varied by 40 degrees. Opening-closing patterns also showed irregularities like those observed in temporomandibular disorders. Irregularities were minor for the hinge-axis point and least for the kinematic-axis point.
In tooth-guided movements "condyle motion" is represented by the traces of any point near the condyle. In opening-closing, however, the trajectory of a single condylar point will not reliably represent condylar motion. For articulator adjustment, condylar angles must not be taken from opening-closing, but only from protrusion. In diagnostic applications, one has to be aware that irregular traces may not only result from dysfunction, but may as well be a result of the choice of reference point.
近期研究表明，单个后参考点的轨迹可能取决于监测点的位置。本研究的目的是量化这种依赖性，并指出其对髁突路径记录临床应用的影响。
对60名无症状志愿者在颌骨前伸、侧方运动及开闭颌运动过程中的下颌运动进行记录。比较包括铰链轴点和运动轴点在内的10个髁突点的同步轨迹模式，涉及长度、倾斜角度、协调性和形状。
在前伸运动中，不同髁突点的轨迹相等，且与监测点的位置无关。Bennett角取决于参考点的矢状位，位置每改变1mm，角度变化0.8度。开闭颌轨迹差异较大。其长度变化可达9mm，倾斜角度变化40度。开闭颌模式也显示出与颞下颌关节紊乱中观察到的类似不规则性。铰链轴点的不规则性较小，运动轴点的不规则性最小。
在牙引导运动中，“髁突运动”由髁突附近任何点的轨迹表示。然而，在开闭颌运动中，单个髁突点的轨迹不能可靠地代表髁突运动。对于咬合架调整，髁突角度不能从开闭颌运动中获取，而只能从前伸运动中获取。在诊断应用中，必须意识到不规则轨迹不仅可能由功能障碍导致，也可能是参考点选择的结果。
