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Electromyographic Changes in the Masseter and Temporalis Muscles Before and After Orthognathic Surgery in Patients With Mandibular Prognathism

González Olivares, Hilda MD*,†; García Pérez, Alvaro PhD; López Saucedo, Francisco MD§; Ángeles Medina, Fernando MD||

doi: 10.1097/SCS.0000000000005395
Clinical Study: PDF Only

Objective: Evaluate the electromyographic changes in the Masseter (MM) and Temporalis (TM) muscles during voluntary clenching of the teeth both before and after orthognathic surgery in patients aged 18 years and older and diagnosed with mandibular prognathism.

Methods: Eleven patients with prognathism were included in the study, in all of whom the initial phase of orthodontic treatment had been completed. The orthognathic procedure to reduce prognathism comprised intraoral oblique sliding (or subsigmoid) osteotomy, after which intermaxillary fixation with ligaments in the maxilla and mandible was undertaken in all patients for 6 weeks post-surgery. Electromyographic activity was recorded during the baseline maximum voluntary contraction of the teeth, with the same measurement taken 3 and then 6 months after orthognathic surgery.

Results: Significant differences were found in the mean amplitude (17.0 vs 14.7, P = 0.020) and peak-to-peak amplitude (left [761.6 vs 457.0, P = 0.003] and right [676.9 vs 357.4, P = 0.007]) for the MM between the baseline score and 6 months after surgery. Likewise, significant differences were found in the mean amplitude (18.2 vs 25.6, P = 0.009) and peak-to-peak amplitude (left [856.4 vs 1594.2, P = 0.004] and right [804.4 vs 1813.4, P = 0.004]) for the TM between the baseline score and that taken 6 months post-surgery. Only 18.2% (2/11) presented orthodontic appliances problem in the 3 months post-surgery.

Conclusion: Electromyographic activity was restored 6 months after the orthognathic surgery. From a clinical perspective, the results obtained confirm that orthognathic surgery has not only an esthetic but also a functional objective in terms of achieving equilibrium and occlusal harmony.

*Maxillofacial Surgery Department, Pediatric Hospital, National Medical Center Century XXI (CMN-SXXI) Mexican Social Security Institute (IMSS)

Postgraduate Dental Program, School of Dentistry, National Autonomous University of Mexico, Mexico City

Pediatric Stomatology Specialties, Faculty of Higher Studies (FES) Iztacala. National Autonomous University of Mexico (UNAM), State of Mexico

§Specialties Hospital of the La Raza National Medical Center of the Mexican Social Security Institute (IMSS)

||Physiology Laboratory at the School of Dentistry of the National Autonomous University of Mexico, Mexico City, Mexico.

Address correspondence and reprint requests to Hilda González Olivares, Maxillofacial Surgery Department, Pediatric Hospital National Medical Center (XXI) Mexican Institute of Social Security (IMSS) Mexico City, Mexico. Avenida Cuauhtémoc 330, colonia Doctores, Delegación Cuauhtémoc, C.P.06720 México, Mexico; E-mail:

Received 24 August, 2018

Accepted 27 December, 2018

The authors report no conflicts of interest.

© 2019 by Mutaz B. Habal, MD.