1990 Volume 53 Issue 4 Pages 381-391
It is well-known that sagittal splitting of the ramus is effective for improvement of the occlusion and facial esthetics of mandibular prognathism associated with an open bite. We treated two mandibular prognathic cases associated with an open bite by orthognathic surgery. However, these two cases showed different post-operative results. We re-evaluated the initial morphology of these cases by Kamiyamas' analysis to elucidate the cause of this difference.
The first case was morphologically a skeletal open bite, although the maxillary anterior alveolar process compensated for the anterior open bite. In this case, post-oper-ative stability of the anterior segment of the mandible was satisfactory.
The open bite of the second case was due to hypoplasia of the mandibular anterior alveolar process. In this case, the orthognathic surgery brought about excessive stress in the soft tissues and muscles around the mandible resulting from the setback and counterclockwise rotation of this segment. Therefore, the clockwise rotation elongated the mandibular incisors, cuspids and first bicuspids during the intermaxillary fixation.
In order to prevent such relapses we should select surgical procedures which reduce excessive stress in the soft tissues and muscles around the mandible by analysing open bite cases by Kamiyamas' method.
