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

Objective. The purpose of this study was to verify the characteristics of surface electromyography (sEMG) of masticatory muscles in patients with temporomandibular disorders (TMDs) with differing pathology. Study Design. A total of 24 patients with TMDs were categorized according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD); magnetic resonance imaging (MRI) classified the patients as having disk displacement alone (DD) (mean age, 22 years; SD, 5; 3 men, 6 women) or having osteoarthrosis with or without disk displacement (OA) (mean age, 37 years; SD, 10; 4 men, 11 women); sEMG was performed according to a standardized protocol. Results. The MRI score was significantly correlated to the torque coefficient (r ¼ 0.57) and the temporalis (r ¼ 0.85) and masseter (r ¼ 0.46) muscle standardized symmetry. The discriminating ability of participant age and sEMG scores in separating the 2 groups was assessed by receiver operating characteristic analysis. Each of the sEMG scores showed a significant ability in discriminating between osteoarthrosis and disk displacement. Conclusions. The recording of the masticatory muscle function through sEMG can be a first diagnostic approach to patients with TMDs, reserving MRI assessment to selected cases.