Evaluation of Mandibular Border Movements and Mastication in Patients with Temporomandibular Disorders: A Pilot Study with 3D Electromagnetic Articulography and Surface Electromyography

Temporomandibular disorders (TMD) are characterized by pain and restricted functionality of the temporomandibular joint (TMJ). The objective of this study was to characterize the kinematic and electromyographic patterns of mandibular border movements and mastication in patients with different forms of TMD compared with healthy controls, through a simultaneous three-dimensional electromagnetic articulography (EMA-3D) and surface electromyography (sEMG) recording protocol. Sixteen participants were included and divided into three groups according to the TMD diagnosis (articular, muscular and mixed) and one healthy control group. Kinematic data were recorded using EMA-3D, and electromyographic activity of the masticatory muscles was assessed using sEMG. Variables analyzed included trajectories, areas, ranges, and electrical activity during mandibular border movements and mastication. Patients with TMD exhibited reduced movement trajectories but larger areas within the mandibular polygons, particularly in the frontal and sagittal planes. During mastication, the number of cycles was higher in the muscular group and lower in the healthy controls. Patients with TMD showed greater mean electromyographic activity, which could suggest compensatory muscle strain. The EMA-3D system provided an accurate threedimensional analysis, while sEMG captured detailed patterns of muscle activation and strain, that help better understand the neuromuscular alterations associated with TMD. Differentiation between TMD types (articular, muscular and mixed) for the study of its kinematic and electromyographic characteristics, is essential to improve diagnosis and treatment strategies. This study highlights the relevance of advanced tools such as EMA-3D and sEMG in the evaluation of TMD using a simultaneous recording protocol such as the one proposed in this study.