Anterior Temporalis and Suprahyoid EMG Activity During Jaw Clenching and Tooth Grinding

Abstract

The aim of this study was to evaluate the anterior temporalis and suprahyoid electromyographic (EMG) activity during jaw clenching and tooth grinding at different jaw posture tasks. The study included 30 healthy subjects with natural dentition and bilateral molar support, incisive protrusive guidance and bilateral laterotrusive canine guidance. Bipolar surface electrodes were located on the right anterior temporalis and suprahyoid muscles. Three EMG recordings in the standing position were performed in the following tasks: C. clenching in the intercuspal position (IP); P1. eccentric grinding from IP to protrusive edge-to-edge contact position; P2. clenching in protrusive edge-to-edge contact position; P3. concentric grinding from protrusive edge-to-edge contact position to IP; L1. eccentric grinding from IP to laterotrusive edge-to-edge contact position; L2. clenching in laterotrusive edge-to-edge contact position; L3. concentric grinding from laterotrusive edge-to-edge contact position to IP. EMG activity during protrusive and laterotrusive tasks was lower than intercuspal position in the anterior temporalis, whereas an opposite EMG pattern was observed in the suprahyoid muscles activity, excepting recorded activity in L2 (mixed model with unstructured covariance matrix). Anterior temporalis activity was higher during P3 than P1 and P2 tasks and during L3 than L1 and L2 tasks, whereas in the suprahyoid muscles, activity was higher during P1 than P2 tasks and during L1 than L2 and L3 tasks. These results could support the idea of a differential modulation of the motor neuron pools of anterior temporalis and suprahyoid muscles of peripheral and/or central origin.

Additional information

Notes on contributors

Karina Aldana

Dr. Karina Aldana received her D.D.S. degree in 2008 from the University of Chile. Dr. Aldana is currently a staff member of the Oral Physiology Laboratory, Biomedical Sciences Institute, Faculty of Medicine, University of Chile. She devotes her professional time to work in oral rehabilitation in several private health institutions and in private practice.

Rodolfo Miralles

Dr. Rodolfo Miralles received his D.D.S. degree in 1975 from the University of Chile. He is a full professor and chief of the Oral Physiology Laboratory, Biomedical Sciences Institute, Faculty of Medicine, University of Chile. Dr. Miralles is a member of the International Association for Dental Research. He is also an associate editor of the Chilean Odontology Journal.

Aler Fuentes

Dr. Aler Fuentes received his D.D.S. degree in 2006 from the University of Talca, Chile. He is an academic of the Faculty of Odontology, University of Chile. Dr. Fuentes is currently a staff member of the Oral Physiology Laboratory, Biomedical Sciences Institute, Faculty of Medicine, University of Chile. He is in training to obtain a Master of Dental Sciences at the University of Chile.

Saúl Valenzuela

Dr. Saúl Valenzuela received his D.D.S. degree in 1990 from the University of Chile. He is an assistant professor of the Prosthetics Department, Faculty of Odontology, University of Chile. Dr. Valenzuela is currently a staff member of the Oral Physiology Laboratory, Biomedical Sciences Institute, Faculty of Medicine, University of Chile. He devotes his professional time to work in oral rehabilitation in several private health institutions and in private practice.

María Javiera Fresno

Dr. Maria Javiera Fresno received her D.D.S. degree in 1988 from the University of Chile and a Master of Oral Rehabilitation in 2006 from the Andrés Bello University, Chile. She is a member of Oral Rehabilitation Department of Andrés Bello University, Chile. She is an assistant professor of Prosthetics Department, Faculty of Odontology, University of Chile. She is currently a staff member of the Oral Physiology Laboratory, Biomedical Sciences Institute, Faculty of Medicine, University of Chile. She devotes her professional time to work in oral rehabilitation in private practice.

Hugo Santander

Dr. Hugo Santander received his D.D.S. degree in 1981 from the University of Chile. He is currently a staff member of the Oral Physiology Laboratory, Biomedical Sciences Institute, Faculty of Medicine, University of Chile. Since 1982, Dr. Santander has dedicated his time and energies to diagnosis and treatment of cranio-cervicalmandibular (CCD) disorders in several private health institutions.

Mario Felipe Gutiérrez

Dr. Mario F. Gutiérrez received his D.D.S. degree in 2007 from the University of Chile. He is an ad-honorem academic of the Restorative Department and of the Oral Physiology Course of the Faculty of Odontology, University of Chile. Dr. Gutiérrez is currently a staff member of the Oral Physiology Laboratory, Biomedical Sciences Institute, Faculty of Medicine, University of Chile. He devotes his professional time to work in oral rehabilitation in several private health institutions and in private practice.