[Control ability to coordination pattern of masticatory muscle activities during maximal clenching in centric occlusal position].

The control ability which changes the coordination pattern of masticatory muscles in the Maximal voluntary clenching was investigated in the correlativity, using the electromyogram and the Dental-Prescale system on ten normal subjects. Even the insignificant correlative Activity index to the balancing point of occlusal force was shown, though the anteroposterior control index (CA/P) marked slightly correlative to the deviation of balancing point, when the coordination pattern of the masticatory muscles was controlled in conscious. Asymmetry index also marked insignificant correlation to the balancing point of occlusal force, but lateral control index (CLat) was significantly correlated under conscious deviation of balancing point. Conclusions were as follows: 1. The balancing point of occlusal force was located at maxillo first molar anteroposteriorly and near the median line laterally. 2. The coordination pattern consisted of nearly equal electromyographic activities during maximal clenching in the masseter and tempolaris anterior muscles in present subjects without the third molar. 3. The diagnosing in coordination pattern of masticatory muscles only using prescale system is difficult. But this system is reliable to estimate the control ability of the muscle coordination pattern. From these result, one of the suggestion in central mechanism of masticatory muscles were undertaken in program of the central nerve system.