Gallo L M, Airoldi G B, Airoldi R L, Palla S
Clinic for Masticatory Disorders and Complete Dentures, University of Zürich, Switzerland.
J Dent Res. 1997 Feb;76(2):704-13. doi: 10.1177/00220345970760021201.
Despite wide use of systems to record jaw motion with six degrees of freedom, most studies have analyzed only the movement of a single mandibular point. The finite helical axis (FHA) is a mathematical model which can be used to describe comprehensively the movements of a rigid body. The aim of this investigation was to describe the FHA of the mandible during habitual jaw movements. Thirty subjects (13 females, 17 males; mean age, 26 years; range, 18 to 34 years) without myoarthropathies of the masticatory system participated in the study. Opening and closing movements, performed at 1-Hz frequency, were recorded with the optoelectronic system Jaws-3D. Three opening and closing movements were recorded from the right side and three from the left side of the jaw. The movement data were low-pass-filtered for noise reduction prior to the computation of the finite helical axis by means of a software program developed in our laboratory. The following parameters were calculated: the rotation of the FHA, its spatial orientation, and the translation along it, as well as its position and distance relative to an intracondylar point. In addition, methodological errors of the model were calculated. During opening and closing, the group mean FHA rotation was 24.3 degrees +/- 4.2 degrees. The group mean of the maximum total translation along the FHA was 0.9 +/- 0.7 mm. The group mean distance between the FHA and the intracondylar point was 48.9 +/- 9.9 mm. The FHA pathways were smooth and varied between individuals. Furthermore, the finite helical axes were never localized within the condyle, and often were located outside of the mandible. The analysis of the FHA pathways yields more information on whole mandibular movements than simply the movements of a single condylar point.
尽管用于记录具有六个自由度的下颌运动的系统被广泛使用，但大多数研究仅分析了单个下颌点的运动。有限螺旋轴（FHA）是一种数学模型，可用于全面描述刚体的运动。本研究的目的是描述习惯性下颌运动过程中下颌骨的有限螺旋轴。30名无咀嚼系统肌关节病的受试者（13名女性，17名男性；平均年龄26岁；范围18至34岁）参与了该研究。使用光电系统Jaws-3D记录以1赫兹频率进行的开闭运动。从下颌右侧记录三次开闭运动，从左侧记录三次。在通过我们实验室开发的软件程序计算有限螺旋轴之前，对运动数据进行低通滤波以降低噪声。计算了以下参数：有限螺旋轴的旋转、其空间方向、沿其的平移，以及其相对于髁内点的位置和距离。此外，还计算了模型的方法误差。在开闭过程中，组平均有限螺旋轴旋转为24.3度±4.2度。沿有限螺旋轴的最大总平移的组平均值为0.9±0.7毫米。有限螺旋轴与髁内点之间的组平均距离为48.9±9.9毫米。有限螺旋轴路径平滑，个体之间存在差异。此外，有限螺旋轴从未位于髁内，且经常位于下颌骨之外。与仅分析单个髁点的运动相比，对有限螺旋轴路径的分析能提供更多关于整个下颌运动的信息。
