Kinematic Modeling of Jaw-closing Movement during Food Breakage

Abstract

It has been demonstrated that the vertical jaw movement trajectories during gum-chewing can be explained by jerk-cost minimization. However, it is uncertain whether the masticatory jaw movement in space can be predicted by the minimum-jerk model. The aims of the present study were to develop minimum-jerk models that would explain 3D masticatory jaw movements with different hardnesses of foods, and to evaluate if the models can predict the movements accurately. The 3D masticatory jaw movement during food breakage was formulated for two types of test foods. The coefficients of determination (R2) between the measured and model-based values ranged from 0.846 to 0.882. Differences were found in the kinematic parameters between the test foods. The results suggest that the models predict the 3D jaw movements during food breakage and are effective in differentiating among the kinematic features of masticatory jaw movements that are peculiar to the mechanical properties of foodstuffs.

Orthodontic Treatment of Malocclusion Improves Impaired Skillfulness of Masticatory Jaw Movements

“…The factual masticatory jaw-movement trajectories were found to be highly correlated with the model-based trajectories, 13,14 which were computed on the basis of a modeling technique 10 reported previously. In addition, jerkcost has been shown to be highly sensitive and proportional to the degree of occlusal interferences that have been experimentally induced by inserting acrylic fillings with varying vertical dimensions.…”

“…A detailed description of the mathematical data processing methods has been reported previously. 13,14 The minimum-jerk model 10,20,21 was applied to the factual jaw displacement trajectory data of the jaw-closing phase for each chewing cycle. The accuracy of the model prediction was measured by using Spearman's correlation coefficient (r) between the actual and predicted velocity profiles.…”

“…In addition, jerkcost has been shown to be highly sensitive and proportional to the degree of occlusal interferences that have been experimentally induced by inserting acrylic fillings with varying vertical dimensions. 15 A previous report 14 has argued that skillfulness of the jaw motion can be diagnosed objectively and sensitively by such kinematic parameters as the normalized jerk-cost and the velocity profile.…”

Restoration of occlusal and proximal contacts by a single molar crown improves the smoothness of the masticatory movement

“…A normalization technique was applied to the jerk-cost data analysis. The normalization technique generates a measure of jerk-cost which is independent of duration and amplitude of the movement (normalized jerk-cost, NJC 22,27 ). The jerk-cost was analyzed at the jaw closing phase because the high NJC during jaw closing in chewing closely relates to a skewed velocity profile with a prolonged period of deceleration.…”

“…The jerk-cost has demonstrated its usefulness as a parameter in the evaluation of masticatory movement. 21,22 One jerk analysis of jaw movement demonstrated that artificial occlusal interferences significantly decreased the smoothness of masticatory jaw movement during gum chewing. 23 Another study used jerk-cost analysis to effectively detect a significant increase of the smoothness of jaw movement after correction of the malocclusions.…”