Anatomical location of various condylar points for jaw movement analysis in Japanese women

The aim of this study was to determine anatomical locations of the hinge axis point, kinematic axis point and reference point for the palpated lateral condylar pole on lateral cephalograms. Subjects comprised 18 Japanese women selected according to following criteria: normal occlusion; and absence of signs and symptoms of stomatognathic function. Jaw movement and the condylar reference points noted earlier were recorded three-dimensionally with six degrees of freedom, and kinematic axis point and hinge axis point were determined using an optoelectronic jaw-tracking system. Lateral cephalograms were used to determine anatomical locations of the three points in the condyle. Mean location of hinge axis point was 12.9 mm anterior of the porion and 5.3 mm inferior to the Frankfort horizontal plane, the kinematic axis point was situated in 12.8 mm anterior and 0.1 mm inferior, and the reference point for the palpated lateral condylar pole was situated 10.7 mm anterior and 0.8 mm inferior, respectively. The kinematic axis point was located outside the condyle in the majority of subjects. The reference point for the palpated lateral pole offers a useful indicator in the analysis of condylar movements.