[A clinical and physiological evaluation of masticatory center in shortened arch]

The aim of this study was to evaluate the influence of occlusal deficit by loss of bilateral posterior molars in masticatory habituation and how to improve by RPD, investigating the location center of occlusal load (by Prescale Fuji Film Co.) and in its amount, in connection with masticatory muscle activities by analyzing EMG. EMG measurements of masticatory masculature at maximal clenching with pressure indicator, were induced at intercuspal position, confirming by MKG. As controls, seven complete dentate adults were referred, the five mandibular and maxillary bilateral molar-edentate cases each of five were investigated. The results were as follows: i) The location of the center of the occlusal load in dentate mouth was about the midline of the maxillar first molar. ii) In the loss of bilateral molars, the center of the occlusal load was in the first premolar area. iii) By prosthodontic treatments the center of the occlusal load was changed to the second premolar area. iv) These results indicated that the prosthodontic treatment was estimated in physiological imperfection of recovery as yet dentate mouth.