Abstract
The active isometric jaw function was studied on 15 stomatognathically healthy subjects. The isometric lateral jaw movement (push laterally) was actively applied for about one minute at the centric and approximately 3mm and 6mm prot-lateral eccentric positions.
The results obtained were as follows:
1) The maximum lateral jaw force was 8.7kgf. This value was decreased with the time (P<0.0001) and was supposed to be nearly equivalent to the force of the ipsi-lateral lateralpterygoid muscle.
2) At the early phase of the excercise, EMG power volue of the ipsi. Tp (67.7 arbit. units) when the maximum lateral jaw force was applied, was larger (P<0.0001) than those of the another muscles tested (ipsi. Mm: 9.2 arbit. units, cont. Mm: 12.6 arbit. units, cont. Tp: 10.7 arbit units).
3) The highest frequency of complaints regard with the fatigue and pain evoked by the excercise was found in the contralateral zygomatic and masseter region (76.9%). These suffering were strongly suspected to be arise from the ipsi-lateral lateral-pterygoid muscle.
