Comparison of Simultaneously Recorded Computerized Occlusal Analysis and Surface Electromyographic Activity of Masticatory Muscles Between Patients with Unilateral TMD.

Abstract

To investigate the relationships among occlusion time, disclusion time, occlusal load distributions, and simultaneous electromyographic (EMG) recordings of the anterior temporalis (TA) and masseter (MM) muscles during centric and lateral movements in patients with unilateral temporomandibular disorder (TMD) pain and in asymptomatic control subjects. Twelve healthy and 13 unilateral TMD subjects participated in the present study. The diagnosis of unilateral TMD was verified with vibrational analysis of the temporomandibular joints (TMJs) using the BioJVA (BioResearch Associates). Simultaneous computerized digital occlusal analysis using T-Scan III (Tekscan) and EMG activity of the MM and TA muscles using BioEMG III (BioResearch Associates) were performed in the intercuspal position and in right and left excursive movements. In intercuspal and lateral movement records, EMG activity of the masticatory muscles, occlusion time, disclusion time, and bite force distribution ratios were evaluated. No statistically significant differences were observed in occlusion time, disclusion time, or EMG activity of the MM and TA muscles between controls and patients with unilateral TMD in the intercuspal position. In unilateral TMD patients, disclusion time of the painful side was significantly higher than in the control group and compared to the nonpainful side (P < .05). Bite force distribution of the balancing side in TMD patients was shown to be statistically significantly higher values than in control subjects. EMG activity of the working-side TA muscle was higher than the nonworking side TA in controls and in the nonpainful side of TMD patients (P < .05). However, EMG activity of both the MM and TA muscles did not show a difference between the working side and nonworking side in unilateral TMD patients. In the intercuspal position, there was no difference in occlusion time, distribution of force, or EMG activity of the masticatory muscles observed between the control group and unilateral TMD pain patients. However, in lateral movements, the painful side of the unilateral TMD patients revealed increased balancing side TA activity, with higher disclusion time and balancing side force distribution.