A study on establishment of the normal range in clinical examination of the masticatory system

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The purpose of this study was established the normal range on several clinical examinations in patients with temporomandibular disorders (TMD).The results obtained were as follows :1. Evoked electromyography and muscle fiber conduction velocity (MFCV)The influence of muscle fatigue and occlusal vertical dimension in the muscle fiber conduction velocity (MFCV) was studied in the healty human masseter and temporal muscle. MFCV was decreased with muscle fatigue and increment of the occlusal vertical dimension.2. EMG profiles of the masticatory musclesEMG profiles of the healthy human masseter (Mm), anterior temporal (Ta) and anterior belly of the digastric muscles (Da) during deliberate unilateral gum chewing showed stable patterns Each peak of EMG profiles of Mm and Ta was observed about 30% of one chewing stroke, but Da was observed about 80% of one chewing stroke.3. T-Scan system for occlusal examinationNormal ranges of the time and force analyzes were obtained from 100 healthy human.4.Pressure pain threshhold (PPT) in masticatory musclesThe daily change of PPT was observed in 10 normal subjects and 4 TMD patients with muscle palpation during splint therapy. No difference of PPT between sides was observed in normal subjects. However, PPT of the painful side was significantly lower than that of the other side before the splint therapy.5. Occlusal contacts in the intercuspal positionOcclusal contacts of the TMD patient were unbalanced in comparison with the normal subject.6. Deep temperature of masticatory musclesNo difference was identified in the deep temperature between the right and left masseter muscles in normal subjects. However, the difference between sides was identified in TMD patients.