Maxillofacial skeletal deformities affect the functional activity of the masticatory muscles. The combination of orthodontic treatment and orthognathic surgery is recommended as an effective way to correct dentofacial deformities beyond the capabilities of orthodontic treatment. This systematic review aims to assess the effect of orthognathic surgery on the changes in the electromyography of the masticatory muscles. A comprehensive electronic search was carried out in compliance with Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. An electronic search was conducted using the following terms: (masticatory muscle activity) AND (electromyographic activity) AND (orthognathic surgery). After an initial search, 2070 scientific records were found, 5 studies that met the eligibility criteria were included in the final analysis. The Joanna Briggs Institute (JBI) tool was utilized to assess the methodological quality of the studies. An average improvement in masticatory muscle activity was observed six months post-orthognathic surgery, according to the analyzed studies. Longer post-surgical follow-up and additional interventions are needed to ensure that the masticatory muscles adapt better to the occlusion and skeletal morphology.
