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 = 0.57) and the temporalis (r = 0.85) and masseter (r = 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.