[Biomechanical relationship between intercusp relation and masticatory movement during final stage of...

The purpose of this study was to investigate the relationship between intercusp relation and masticatory movement during the occlusal phase by dynamic evaluation of the efficiency of mastication. The methods and the results were as follows: 1. Study of model The efficiency of mastication of cusp-to-cusp model A and cusp-to-fossa model B relationship models was highest in the movement from mesial to distal and from buccal to lingual sides for A and B, respectively. 2. Study of clinical data 2.1 The masticatory movement of (case-A) and of (case-B) having been evaluated, case-A, compared with case-B, had a greater anteroposterior movement, and there was little difference in the efficiency. 2.2 In postorthodontic treatment, the alteration of movement from anteroposterior to lateral direction was observed. The results indicated that the efficiency of mastication is determined not only by the static contact morphology of maxillary and mandibular teeth but also by the dynamic masticatory movement, adjusting to the morphology according to the intercusp relation of teeth. The direction of the adjusted masticatory movement compensated for the position and occlusal morphology of teeth to increase the efficiency as verified by the simulation and clinical data.