Surface electromyography and magnetic resonance imaging of the masticatory muscles in patients with arthrogenous temporomandibular disorders

The purpose of this study was to verify the characteristics of surface electromyography (sEMG) of masticatory muscles in different temporomandibular disorder (TMD) patients. Twenty-four TMD patients were categorized according to the RDC/TMD; Magnetic Resonance Images (MRI) classified patients with disk displacement (DD, mean age 22 years, SD 5; M/F: 3/6), and osteoarthrosis and/or disk displacement (OA, mean age 37 years, SD 10; M/F: 4/11); sEMG was performed according to a standardized protocol. The MRI score was significantly correlated to torque coefficient (r=0.57), temporalis (r=0.85) and masseter (r=0.46) muscle standardized symmetry. The discriminating ability of subject age and EMG scores in separating the two groups was assessed by ROC analysis. Each of the EMG scores showed a significant ability in discriminating between osteoarthrosis and disc displacement. The recording of the masticatory muscle function through sEMG can be a first diagnostic approach to TMD patients, reserving MRI assessment to selected cases.