Smartphone-assisted monitoring of masticatory muscle activity in freely moving individuals.

To test a smartphone-assisted wireless device for assessing electromyographic (EMG) activity of the masseter muscle in freely moving individuals undertaking routine activities. EMG activity was detected unilaterally from the masseter muscle in 12 volunteers using surface electrodes connected to both a smartphone-assisted wireless EMG device and a fixed-wired EMG equipment (reference standard). After performing a series of standardized tasks in the laboratory, participants wore the wireless device for 8 h while performing their normal routine. The wireless device reliably detected masseter muscle contraction episodes under both laboratory and natural environment conditions. The intraclass correlation coefficients for the muscle contraction episode amplitude and duration detected by the wireless and the wired equipment ranged from 0.94-1.00 to 0.82-1.00, respectively. Most masseter contraction episodes during normal routine were of low amplitude (< 10% MVC) and short duration (< 10 s), with no significant differences between sexes or facial side. Within the limitations of the study, smartphone-assisted monitoring of the jaw muscles represents a promising tool to investigate oral behavior patterns in free moving individuals. Smartphone-assisted monitoring of masticatory muscle activity may enable possible associations between excessive muscle activity, bruxism, dysfunction, and pain to be investigated, and managed via biofeedback.