[Geometrical investigation on mechanism and movement of Gysi Simplex OU articulator]

Gysi Simplex OU articulator was constructed by modifying Gysi Simplex 1914, and has been used for students' practice of complete denture construction at 18 Japanese dental schools. Therefore, the mechanism and movement of the articulator should be explained and understood clearly from the educational standpoint of view. In this study, the movement was analyzed by geometrical drawing after Ishiwara-Suetsugu's simplified method. The following results were obtained: 1. Sagittal inclination of incisal guidance acted as an important role for location and inclination of lateral axis. 2. Accessory working condylar guide, which is located behind the condyle post, is another important mechanism as one of determinants of the movement. 3. The lateral wall of balancing condylar guide should be forced to touch always the balancing condyle. 4. It was clarified that the movement of Gysi Simplex OU followed the Gysi's axis theory.