Electromyogram Biofeedback Threshold Determination for Clenching Behavior

• Published in: Nihon Hotetsu Shika Gakkai Zasshi Vol. 47; no. 2; pp. 316 - 325
• Main Author: Ogawa, Yu
• Format: Journal Article
• Language: Japanese
• Published: Japan Prosthodontic Society 2003
• Subjects: biofeedback; clenching; electromyogram; pain in masticatory muscles; threshold
• ISSN: 0389-5386; 1883-177X
• DOI: 10.2186/jjps.47.316

Purpose: To establish the electromyogram (EMG) biofeedback threshold for a patient with masticatory muscle pain under a natural environment, various thresholds that differentiate the parafunctional activities from functional ones were determined. Methods: Thirty-four healthy, natural-dentition subjects (18 males, 16 females; mean age, 26.6± 2.7 years old), having no temporomandibular disorder symptoms, were recruited for this study. By means of a newly developed one-channel portable EMG recording device, surface EMG from the unilateral temporal muscle was recorded for 5 hours, under a natural environment. At the beginning and the end of the recording period, EMGs of functional activities (gum chewing and rice cracker consumption), and parafunctional ones (clenching at 10, 30, 50% of maximum bite force; MBF), were recorded. Bite force was regulated by visual feedback from the indicator of a bite force meter. Various combinations of EMG activity (10, 20, 30% of maximum voluntary contraction in RMS value) and EMG duration (1-9s) were determined for recorded EMGs of functional and parafunctional mandibular movements. Results: The thresholds set at the beginning of the recording were applicable even at the end of the recording under clenching at 10, 30 and 50% MBF, to differentiate from the functional activities in 25 (73.5%), 30 (90.9%), and 30 (90.9%) subjects, respectively. Conclusions: The results of this study support the rationale of utilizing EMG activity together with a certain period of duration as a threshold for biofeedback training for the patient having clenching behavior.