Assessment for occlusal vertical dimension based on the subjective and objective

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Sensory-motor alteration in response to the changes of occulusal vertical dimension (OVD) was investigated in dentate and edentulous subjects. In dentate subjects, the change in OVD was associated with the changes in masticatory muscle activity during clenching and in lip-seal force. During wakefulness, functional and non-functional masticatory muscle activities occurred in association with a possible fluctuation of mandibular position. In edentulous subjects, occlusal conditions were associated with their oral functions. When two dentures with different occlusal heights were used for a monthm, chewing performance was improved for the denture, OVD of which were determined by comfortable zone of OVD compared to the denture with OVD referred to the denture previously used. However, proprioceptive evaluation did not differ for the two dentures. The results of these studies suggest that sensory-motor adaptation to occlusal height requires a certain period after a new OVD was established. T … More he underlying biological basis were investigated in animal models. Jaw muscle activity fluctuates during sleep-wake cycle as well as mandibular positions. In bite-raised guinea pigs, OVD decreased to the normal level. During chewing at a bite-raised period, masticatory muscle activity increased but maximum opened position of the jaw and masticatory rhythm did not altered. When jaw opening range was experimentally limited, lower OVD was established compared to those of non-treated animals. Using neuroanatomical techniques, specific neural connections were found between the cortical masticatory areas and thalamus. These suggest that OVD is strictly controlled for performing adequate oral functions but the change in OVD induces adaptive oral behaviors under central nervous system functions. Taken together, subjective assessment of proprioceptive perception and oromotor functions, in addition to the objective assessment of them, are needed to determine adequate occlusal height for each patient and to evaluate sensory-motor adaptation to the clinically established occlusal vertical dimension. Less