[Movement analysis of Gysi Simplex OU articulator. 1. Rotational point and lateral axis]

Several researches have been reported on the mechanism and movement of Gysi Simplex OU articulator. And it was clarified logically by geometrical drawing method that the movement of the articulator followed the Gysi's axis theory. But no study reported about the movement of the articulator by measuring it. Therefore, the authors measured the movement of the articulator with Kyushu University 3-D movement analyzing system, and compared it with the results obtained from geometrical drawing method which we reported previously. The following results were obtained: 1. The rotational point exists actually at the same position where we analyzed by geometrical drawing method. 2. Lateral axis is constructed by joining the rotational points at various height. 3. The inclination of lateral axis changes by sagittal inclination of incisal guidance. As the results, we clarified that the movement of Gysi Simplex OU followed the Gysi's axis theory.