THE EFFECT OF 4 JAW RELATIONS ON ELECTROMYOGRAPHIC ACTIVITY IN HUMAN MASTICATORY MUSCLES

Significant differences were found in the electromyographic (EMG) acti vation between the masseter and temporalis muscles for the leaf gauge (LG), manually manipulated (CR) and neuromuscular (NM) bite positions during maximal static clench. The LG position consistently demonstrate d the lowest EMG activity, while the NM position displayed the highest degree of muscle activity. Similarly, the ratio of the masseter/tempo ralis EMG activity during maximal clench was lower for the LG and CR p ositions and highest for the NM position. These data indicate that the NM position produced the greatest total muscle recruitment, with more masseter involvement during maximal clench, and enabled the subjects to generate greater clenching forces in the NM position as compared to the LG and CR positions.