[Relationship of the movement of mandibular condyle and occlusal force balance]

The present investigation evaluated the relation between the dynamic properties of the bilateral condyle in habitual maximum opening and closing movement and the occlusal force balance with clenching force.

Nine normal adults participated in this study. The translation of bilateral condyle and the rotation of intercondylar axis in habitual maximum opening and closing movement was measured using Cadiax, (ver. 3.0). The amount of translation and the rotation were converted into percentages and plotted on a graph using the translation-rotation relative chart. The maximun difference (d) between right condyle and left condyle of translation in rotation was calculated. The maximum clenching force was measured using Dental prescale 50H, type R and Occluzer FPD-703 (Fujifilm Co., Ltd.) and the center of gravity of the occlusal force was plotted on the drawings in two dimensions (anterior-posterior, right-left).

1. The reproducibility of the dynamic properties of bilateral condyle in habitual maximum opening and closing movement and (d) were shown on the translation-rotation relative chart. 2. It was observed that the center of gravity of the occlusal force of a number of subjects was almost localized on the median line with right-left dimension and was localized on the molar tooth area with anterior-posterior dimension. 3. The correlation coefficient was 0.33 between the coordinate value of the center of gravity of the occlusal force with right-left dimension and the path of opening's (d). The coefficient was 0.71 between the coordinate value of the center of gravity of the occlusal force with right-left dimension and the path of closing's (d).

The present study showed the correlation between the dynamic properties of the bilateral condyle in habitual maximum opening and closing movement and the occlusal force balance with maximum clenching force.