ELECTROMYOGRAPHIC ASSESSMENT OF NONFUNCTIONAL MASSETER MUSCLE IN AN AWAKE ANIMAL-MODEL

Non-functional activities, such as bruxism, have been implicated in th e development of temporomandibular disorders (TMD). It would be of val ue to have an animal model in which to investigate the processes under lying such disorders. The aim of this study was to determine the elect romyographic (EMG) characteristics of experimentally induced, non-func tional activity in the jaw-closing muscles of awake, behaving rats and how the EMG characteristics differed from those found under normal co nditions. In the same animals, chronic EMG recordings were made prior to and following the insertion of an occlusal cap, which induced non-f unctional activity. A characteristic EMG pattern was found only during non-functional activity. The durations and amplitudes of the EMG burs ts during this activity were significantly different statistically fro m those found in the same animals under normal conditions.