EMG DIFFERENCES BETWEEN WEAK AND STRONG MYOGENOUS CMD PATIENTS AND HEALTHY CONTROLS

Electromyographic and clinical characteristics of 42 myogenous craniom andibular disorder (CMD) patients were related to 40 healthy control s ubjects. Surface EMG recordings were obtained from the masseter and th e temporal muscles. The clinical examination included active maximum m outh opening, endfeel distance, active laterotrusion and lateral endfe el distance, dental abrasion, the presence of a lateral slide (RCP-ICP ) and the amount of static pain. Orthopantomographic X-rays were avail able from 32 CMD patients for measuring the condylar and ramus asymmet ry. Compared to the control group lower masseter and temporal EMG ampl itudes were found for myogenous CMD patients (P < 0.001). When the act ivity of the temporal muscle was compared with the activity of the mas seter muscle, the CMD patients showed proportionally higher temporal m uscle activities than the controls (P < 0.05, 50% clenching level). CM D patients also showed smaller mandibular excursions, larger endfeel d istances and more dental abrasion than controls. The temporal muscle a symmetries showed significant negative correlations with the ramus asy mmetries. The lower and upper quartile of the distribution of the mean masseter EMG amplitudes were used to distinguish weak and strong musc les in patients and controls. Weak patients showed proportionally high temporal muscle activities, larger masseter and temporal muscle asymm etries, and larger endfeel distances compared to strong CMD patients. These differences were not found between weak and strong controls. In conclusion, it can be said that the electromyographic and clinical fin dings of the myogenous CMD patients suggest a functional difference be tween weak and strong patients and indicate the need for more individu ally designed treatment modalities for functional muscle and joint CMD problems.