Orthodontic Treatment Outcomes in Jaw Motor Function Evaluated by Jerk-costs of Masticatory Jaw Movements

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(1)As regard to chewing jaw movements for adults with mandibular prognathism, impairment of the movement smoothness (higher values of the movement jerk-cost) and lower peak velocity have been determined as compared to those for the adults with acceptably good occlusaion.(2)An arbitrary plane could explain 99% of jaw movement trajectory in each single chewing cycle. The orientations of the planes that represent each chewing cycle performed by the subjects with anterior cross bite were more variable than those observed in subjects with acceptable good occlusion. After correction of the anterior cross bite, however, the variability of the plane orientations for the patients group was reduced. Based on a minimum variance theory, it is suggested that the gum-chewing cycle recorded after correction of the anterior cross bites is characterized as smooth and well patterned.(3)An new measurement algorithm, which is capable of sensitive monitoring of the smoothness of the jaw movement in speech articulation, has been developed.(4)Analytical simulation based on jerk-optimal criterion was developed in order to quantify and diagnose extent to which temporomandibular disorder affect the masticatory jaw motor function.(5)In case reports, it has been demonstrated that optimization of gum-chewing kinematics could occur as a result of orthodontic treatment of patient with prognathism and anterior cross bite. The improvement of the jaw kinematics was indicated by both normalized jerk-cost and prediction accuracy of the simulation by the minimum-jerk model.