外科的矯正治療前後における前歯部開こう症例の口唇，頬，舌圧の変化

Abstract

Many anterior openbite cases show the abnormal functions of perioral soft tissues, and these can cause abnormal occlusion and relapse after surgery.The purpose of this study was to investigate the role of perioral soft tissues in the construction of occlusion and dental arches.Female adult Class M anterior open bite cases that had received orthognathic surgery (surgery group), and female adults with normal occlusion, were selected for this study. Materials of the surgery group were corrected at the period of pre-orthognathic surgery (pre-surgery), six months after debonding (short span), and later (middle span).Soft tissuepressures were measured with subminiature pressure sensors at 8 points on teeth and the hard palate. Tongue size, the length and width of the lower dental arch and the lower basal arch, were also measured.The results obtained were as follows. 1) The pressures of the pre-surgery group were lower than those of the middle span group. In the short span group, soft tissue pressures increased at thefrontal area, and decreased at the posterior area. 2) Thepressures of the normalocclusion were higher than the pre-surgery group, and the short span group was equal to or lower than the middle span group. 3) Contact ratios of the short spangroup were higher than those of the pre-surgery group. But, in the middle span group, contact ratios decreased at the frontal area and increased at the posterior area. Otherwise, the contact ratio of the normal group was higher than that ofthe pre-surgery group, and equal to that of middle span group. 4) No differenceswere found regarding measurements of the tongue and the dental arches among the groups. But the length of the tongue at normal occlusion was longer than in the pre-surgery group. The width of the tongue in the short span group was greater than that of the normal occlusion.These results demonstrate that orthognathic surgery would change the pressures and contact ratio of the soft tissues. And it suggests that perioral soft tissues might be adapted functionally to new environments following surgical treatment.