We hypothesized that the motor response of the masticatory system to peripheral inputs varies according to the functional potential of an individual. The specific aim of the present study was to determine whether individually different types of masticatory patterns, especially with respect to the closing movement pattern, would produce different motor responses to an alteration of occlusal guidance. The inclination of the occlusal guidance was steepened by approximately 10 degrees by attaching a metal overlay to the lingual surface of the maxillary working-side canine. The masticatory movements of 20 young adults were measured using a three-dimensional mandibular movement analysis system before and after the alteration of occlusal guidance. The individual masticatory patterns were divided into two groups based on the closing movement pattern before the alteration of occlusal guidance, i.e. vertical and lateral types. The alteration of occlusal guidance significantly influenced the masticatory closing angle, closing time, occlusal time, the stability of the opening angle and the cycle time in the lateral-type group (n = 9, paired t-test; P < 0;05), while no significant changes were found in the vertical-type group (n = 11). These differences in motor response between the two groups were not found in the overall analysis of all the 20 subjects. We concluded that the oral motor response to the alteration of occlusal guidance depends on the individual masticatory movement pattern. Because the present analysis of subgroups of the subjects revealed motor response findings different from those in the overall analysis of all the 20 subjects, such potential subgroupings should be considered as an attempt to identify a specific effect of peripheral inputs on masticatory function in humans.

We hypothesized that the motor response of the masticatory system to peripheral inputs varies according to the functional potential of an individual. The speci®c aim of the present study was to determine whether individually different types of masticatory patterns, especially with respect to the closing movement pattern, would produce different motor responses to an alteration of occlusal guidance. The inclination of the occlusal guidance was steepened by approximately 10 degrees by attaching a metal overlay to the lingual surface of the maxillary working-side canine. The masticatory movements of 20 young adults were measured using a three-dimensional mandibular movement analysis system before and after the alteration of occlusal guidance. The individual masticatory patterns were divided into two groups based on the closing movement pattern before the alteration of occlusal guidance, i.e. vertical and lateral types. The alteration of occlusal guidance signi®cantly in¯uenced the masticatory closing angle, closing time, occlusal time, the stability of the opening angle and the cycle time in the lateral-type group (n = 9, paired t-test; P < 0 á 05), while no signi®cant changes were found in the vertical-type group (n = 11). These differences in motor response between the two groups were not found in the overall analysis of all the 20 subjects. We concluded that the oral motor response to the alteration of occlusal guidance depends on the individual masticatory movement pattern. Because the present analysis of subgroups of the subjects revealed motor response ®ndings different from those in the overall analysis of all the 20 subjects, such potential subgroupings should be considered as an attempt to identify a speci®c effect of peripheral inputs on masticatory function in humans.

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Abstract:The purpose of this study was to determine whether or not there was any correlation between canine guidance and condylar paths during mandibular lateral movement. Lateral movements were measured on 40 normal young adults using the six-degrees of freedom mandibular movement analyzing system, and the movement data were analyzed on 75 sides where no balancing-side contacts were observed.Canine guidance was evaluated as the frontal inclination of the working-side canine path at 2.0mm from the intercuspal position. The variables to analyze condylar movement were the anterior, lateral and inferior components of the working-side and balancing-side condylar paths. The results were as follows:1. There were significant correlations between the canine guidance and the anterior (r=0.59, p< 0.0001) and inferior components (r=0.41, p<0.0005) of the working-side condylar path. This indicates that the subject with a steep canine guidance has a large amount of the anterior and inferior components of the working-side condylar path, and that, the subject with a flat canine guidance has a large amount of the posterior and superior components of the working-side condylar path.2. On the other hand, no significant correlation was found between the canine guidance and any components of the balancing-side condylar path.