Nocturnal Masseter EMG Activity of Healthy Subjects in a Natural Environment

Abstract

Facial pain of patients with craniomandibular disorders might be caused by muscle overload. However, the activity of masticatory muscles of healthy individuals is still unknown. The aim of this study was therefore a first attempt to clarify this question by recording the masseter muscle activity of healthy subjects during sleep by means of portable recorders. The study was performed on 21 healthy subjects selected after telephone and questionnaire screenings and clinical examination from among randomly selected inhabitants of Zürich. The masseter EMG was recorded during seven nights in each subject's natural environment with the electrodes in reproducible position. The signal was analyzed for number, amplitude, and duration of contraction periods defined as signal portions above a threshold which could contain sub-threshold signal portions shorter than the standby time of 5 sec. The signal amplitude was expressed in percent of the amplitude recorded during maximum voluntary clenches (%MVC). An average of 71.9 +/- 28.7 contraction episodes per night (men, 74.7 +/- 30.1; women, 65.0 +/- 23.8; p = 0.043), i.e., of 10.5 +/- 3.8 per hour (men, 11.0 +/- 4.0; women, 9.3 +/- 3.0; p = 0.005), was found. The average mean amplitude was 26.2 +/- 6.4% MVC (men, 27.0 +/- 6.8; women, 24.4 +/- 4.5; p = 0.009). The duration of the episodes had a mode of 0.5 sec, and the group mean of the integral of the amplitude over time was 123.7 +/- 157.9% MVC (men, 138.9 +/- 184.0; women, 85.9 +/- 28.2; p = 0.005). Healthy subjects showed intermittent periods of masseter activity during sleep which, on average, were of rather low intensity and short duration.

A pilot study of nocturnal temporalis muscle activity in TMD diagnostic groups of women

“…5, 19-22 The numbers of clenches per night in each diagnostic group were similar to previous reports for bruxer and non-bruxer groups. 20 Mean durations of clenching behavior in the current study was similar to some previously reported data 8 but shorter compared to other reports.…”

“…20 Mean durations of clenching behavior in the current study was similar to some previously reported data 8 but shorter compared to other reports. 19, 21, 22 The latter differences may be attributed to different EMG amplitude threshold criteria used to define onset and duration of clenching. The results suggested that all subjects generally activated their temporalis muscles at low magnitudes at night, but average duration of activation was longer in +DD+P than -DD-P subjects.…”

Clenching TMJs-Loads Increases in Partial Edentates: A 3D Finite Element Study

“…Weaver and Co., Nucla Way, Au, CO, USA) and rubbed with grinding paper to reduce impedance, surface EMG signals were obtained using 10-mm bipolar gold surface electrodes (Nicolet Biomedical, Madison, WI, USA) with a 2-cm electrode distance. 12 Conductive paste (Ten20 TM , D.O. Weaver and Co.) was applied and the electrodes were attached and secured by adhesive pads (Omnifix Ò , Unitex-Hartmann S.A., Mataro´, Barcelona, Spain).…”

Bioelectrical Activity Changes of Selected Muscles of the Face and Neck in Patients with Unilateral Cancer of the Oral Cavity Before and After Surgery

“…Limitations of this method include being less accurate than tests using intramuscular needle electrodes, and sensitivity to external factors such as incorrect preparation of skin surface, salivary fistula in the chin area, excessive sweating, nonhealing wounds, or uncontrolled saliva dribbling from the mouth. The advantage of surface electromyography is the ability to compare ratings of bioelectrical activity in balance, and during intensive muscle work [34][35][36][37][38][39][40].…”