Electromyographic assessment of non-functional masseter muscle in an awake animal model

Non-functional activities, such as bruxism, have been implicated in the development of temporomandibular disorders (TMD). It would be of value to have an animal model in which to investigate the processes underlying such disorders. The aim of this study was to determine the electromyographic (EMG) characteristics of experimentally induced, non-functional activity in the jaw-closing muscles of awake, behaving rats and how the EMG characteristics differed from those found under normal conditions. In the same animals, chronic EMG recordings were made prior to and following the insertion of an occlusal cap, which induced non-functional activity. A characteristic EMG pattern was found only during non-functional activity. The durations and amplitudes of the EMG bursts during this activity were significantly different statistically from those found in the same animals under normal conditions.