Endurance of jaw elevator muscles during cementation of a single molar crown.

Muscle activity of four jaw-closing muscles was monitored in 19 healthy subjects by EMG, under conditions associated with cementation of a crown restoration. Each subject performed two maximum voluntary contractions (MVC), each of two minutes duration, separated by a thirty-minute time interval. There was no visual feedback of muscle activity. Local analgesia, psychologic reinforcement and actual cementation were other conditions tested. All muscles fatigued as a function of time. For this experimental procedure the ipselateral muscles demonstrated less endurance than contralateral muscles. Psychologic reinforcement did not alter muscle activity. The effect of local analgesia was inconclusive and requires further investigation.