An Electromyographic Study of Masseter and Anterior Temporalis Muscles in Extra-Articular Myogenous TMJ Pain Patients Compared to an Asymptomatic and Normal Population

Abstract

The purpose of this study was to evaluate the effectiveness of the therapy with a centric relation stabilization appliance (CRSA) in patients with temporomandibular disorders of myogenous origin by electromyography and compare the results with two asymptomatic control groups. Three groups of 20 patients each were selected for the study. Electromyography (EMG) of masseter and anterior temporalis muscles was performed during mandibular rest position. In the treated group, the occlusal appliance reduced the electrical activity of the analyzed muscles at right and left sides (p<0.0001), and equilibrated muscular activity between right and left sides (p<0.0001), reaching values close to the control groups. Although there was not a statistically significant difference, the normal control group presented lower EMG values than control group II and presented the lowest asymmetry index of all subjects. More than 85% of all subjects, including the controls, demonstrated a statistically significant temporal anterior activity prevalence (p<0.0001). Treatment with the CRSA reduced the activity index, although the prevalence of the temporal muscle over the masseter was maintained. The significant laterodeviating (torque) effect found in the temporomandibular disorder patients was reduced after treatment. No side prevalence was found in the control groups.

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Notes on contributors

Valdecir Scopel

Dr. Valdecir Scopel is a graduate of the Department of Orthodontics of the Center for Professional Development, Brazilian Association of Dentistry, Curitiba, Brazil. He is currently in private practice in Curitiba, Brazil.

Gilce S. Alves da Costa

Dr. Gilce S. Alves da Costa received her D.D.S. degree from the Ponta Grossa State University, Paraná, Brazil in 1983. She has a specialty degree in pediatric dentistry from the Federal University of Rio de Janeiro and a specialty degree in orthodontics from the Federal University of Paraná. She is currently a professor of orthodontics at the Center for Professional Development, Brazilian Association of Dentistry, Curitiba, Brazil. Dr. Alves da Costa has been in private practice for 19 years.

Dayse Urias

Dr. Dayse Urias received her D.D.S. degree from the Federal University of Paraná in 1981 and her M.S.D. in orthodontics from Case Western Reserve University, USA in 1985. Formerly a clinical professor at the Federal University of Paran, Dr. Urias is currently professor and chair of the Center for Professional Development, Brazilian Association of Dentistry, Curitiba, Brazil. Dr. Urias has been in private practice for 20 years and has lectured extensively throughout Brazil.