An EMG instrument designed for bruxism detection on masseter muscle

Sleep bruxism (SB) is one of the unsolved problems in dentistry characterized by grinding or clenching of teeth during sleep. Without exact treatment procedure, dentists attempt to alleviate SB symptoms and prevent worsen problem of teeth. Biofeedback method is recently interested because it can change abnormal activity to normal activity for improving quality of life in patients by generating some stimuli feedback back to patients after abnormal activity which is detected by a device. And that normal activity is permanent over time after removal of the device. The aims of this study are to investigate maximum voluntary contraction (MVC) of masseter muscle, and to design a portable particular purposed electromyography (EMG) device for detection of SB activity. 20 participants with average age 21.5 years old were asked to clenching and grinding their teeth for mimicking SB activity and recorded EMG signal for greater analysis. EMG signal of MVC showed maximum value around 870 mV and had powerful frequency of 100 to 400 Hz. An EMG device was designed to be the first part of biofeedback system which amplifies the signal around 5,000 times with frequency selection in boundary of 100 to 500 Hz for selecting clenching and grinding signals.