The Masticatory Cycle in Patients with Temporomandibular Disorders: An Integrated Electromyographic and Kinematic Analysis—A Correlation Study

The masticatory cycle is a coordinated sequence of mandibular movements closely associated with masticatory muscle activity. However, the chewing pattern may be altered in temporomandibular disorders (TMDs). The aim of this study was to evaluate the masticatory cycle in patients with TMD through an integrated electromyographic and kinematic analysis, comparing the results with the correlations previously reported in the literature for healthy subjects. In this cross-sectional study, twenty-four adults diagnosed with TMD (mean age: 26 ± 6.7 years; 16 females and 8 males) were recruited at the Department of Dentistry at San Raffaele Hospital, Milan. The jaw tracking system Modjaw® (version 3.6.4; MODJAW SAS, Villeurbanne, France) made it possible to record three-dimensional mandibular movements, including opening and closing, protrusion, lateral movements and the masticatory cycle. As for surface electromyography, the Myowise® device (software version 1.4; Cometa S.r.l., Bareggio, Italy) was used to assess the electrical activity of the masticatory muscles during chewing. Subsequently, descriptive statistics were performed, and possible correlations between selected kinematic and electromyographic parameters were investigated. No statistically significant correlations were identified, except for a moderate negative correlation between right masticatory cycle height and right masseter muscle impact. Mandibular kinematics showed limited associations with electromyographic parameters in patients with temporomandibular disorders, differing from the correlations previously reported in healthy subjects.