Abstract
In this studies, the author investigated changes in upright posture in 5 healthysubjects while the mandibular position altered for 1 and 5 minutes in a horizontal direction at the distances of 2.5 and 5.0mm. Namely, loci of gravity fluctuation were examined under analysis system in order to reveal what effect were given upon the upright posture. At the same time, electromyograms were obtained from mascles of masticatory system, neck and lower extremity for the observation of the effects on gravitymuscles. The results obtained were as follows:
1. Loci of gravity fluctuation
1) Loci of gravity fluctuation tended to increase beyond the normal range when the mandibular position was horizontally changed for 1 and 5 minutes at the distances of 2.5 and 5.0mm.
2) Changing amounts were less in the anterior direction than in the right and left directions.
2. Activities of antigravity muscles Although muscular activities showed similar tendencies to those of loci of gravity fluctuation they showed individual differences
3. Since these results revealed that horizontal changes in mandibular position influenced both loci of gravity fluctuation and muscular activities, it was suggested that changes in the stomatognatic system are involved the systemic condition, and that the recovery of adequate function of the stomatognatic system is essential to the maintenance of systemic harmony.
