Current status of researches on jaw movement and occlusion for clinical application

Although many dentists agree that occlusion is one of the most important factors for dental clinics, evidence for this conclusion among contemporary clinical dental procedures is very limited. The lack of appropriate measurement and recording methods for dental occlusion may be responsible for this inconsistency. If transitional occlusal contact points on dentition during functional jaw movement can be observed graphically, it will dramatically improve the realization and evaluation of dental occlusion for both research and clinics. This technology is now available by computing the distance between the maxillary and mandibular occlusal surfaces during jaw movement. This visualization of occlusion requires a three-dimensional configuration record of the maxillary and mandibular dentitions and six-degree-of-freedom jaw movement data with a 10-μm accuracy level. We recently developed a new jaw-tracking device consisting of a pair of three-axis coils to satisfy these quality requirements. Improvement of three-dimensional digitizers with a laser beam system will be necessary for precise acquisition of the occlusal configuration. For analyses of occlusion and six-degree-of-freedom jaw movement, we propose two different mathematical ideas to represent jaw movement. The first is mandibular movement, i.e. mandibular motion against the maxilla, and the second is complementary mandibular movement, i.e. maxillary motion against the mandible. Eighteen-degree-of-freedom movement involving maxillary and mandibular teeth movements will be required for research in the near future.