[Influence of occlusal contacts on tooth displacement]

During function, the tooth displacement path depends on occlusal contacts of the upper and lower teeth. Therefore, we must reconstruct occlusal relation carefully so as not to disturb physiological tooth displacement. In this investigation, tooth displacements were measured with the Displacement Transducer type M-3 in varying occlusal contact. The following conclusions were obtained. 1. The location of occlusal contacts influenced the tooth displacement of the upper first molar. Especially, an occlusal contact on the lingual inclination of the lingual cusp, buccal cusp had great influence. The tooth showed displacement toward the buccal direction, and it differed from the physiological tooth displacement path during clenching at the intercuspal position. 2. The location of occlusal contacts had little influence on the tooth displacement of the lower first molar. The tooth showed displacement toward the lingual direction. It was similar to the physiological tooth displacement. 3. On the upper first molar, the location of occlusal force influenced the Stress-Strain curve. Especially, the occlusal force on the buccal cusp had great influence on the amount of tooth displacement. 4. On the lower first molar, the location of occlusal force influenced the Stress-Strain curve. Especially, the occlusal force on the lingual cusp brought much displacement and a 2-phase displacement path, at times. Therefore, occlusal contacts have close relation to tooth displacement, and any occlusal reconstruction should harmonize with tooth displacement representing periodontal tissue distortion.