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.

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The purpose of this study was to investigate adaptation of the masticatory muscles to the altered jaw relationship that had been brought by orthognathic surgeryin patients with jaw deformities.
The subjects were 5 patients with jaw deformities, and the control group was 19 people with normal occlusion. The masseter and the anterior temporal muscle activities at the maximum clenching were measured at the initial examination, 6 months, and 1 year after operation by electromyography. The activity index of relating masseter muscle to temporal muscle was calculated.
The results were as follows:
1. The activity index increased 1 year after orthognathic surgery. This result showed that the masetter muscles had beengetting work more active than temporal muscles like the control group.
2. The patterns of the increase in the activity index of jaw deformity cases varied individually.

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An orthognathic surgical simulation system that integrates morphological data onteeth, jaws, and faces into a coordinate system with a computer, was developed.
Morphological data on the upper teeth and the facial surfaces were obtained from laser scanners. All the data were integrated in the reference coordinate system of frontal and lateral cephalograms.
A technique used for this integration was to match the data of teeth and faces to a pair of cephalograms on a computer. This method (projection matching technique) is especially useful for the integration of objects that have a difficulty to pick up anatomical landmarks because of their spherish shape, like facial surfaces.
The patient's mandibular shape was simulated in the computer by transforming a generic model to match the patient's cephalograms. Thus, various designs of mandibular osteotomies can be simulated on the computer without using CT data. The movement of bone and collisions between segments that might be caused with each operation method can be analyzed. This system will be useful for selection of an operative method, especiallyone aimed at considering facial soft tissue shape changes.

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The aim of this article is to discuss the effectiveness of clockwise rotation of the occlusal plane for skeletal class III deformities with the use of two-jaw surgery.
The most popular orthognathic surgical management for class III malocclusion is mandibular setback using a bilateral sagittal splitting ramus osteotomy (SSRO). However, it has been suggested that, with the aid of an operative method using SSRO alone, complete elimination of the protruded appearance in the mental region is hardly attainable, in some cases. To obtain better functional and esthetic results for patients with class M deformities, clockwise rotation of the occlusal plane, using two-jaw surgery, appears to be considerably useful surgical management. The changes provided by an increased occlusal plane angle include 1) advancement of the midface; 2) rotation of the chin posteriorly; 3) a decreased maxillary incisor angle; 4) an increased mandibular plane angle; 5) decreased posterior facial height. We emphasize that, by appropriate usage of clockwiserotation of the occlusal plane, more favorable functional and esthetic results for the correction of skeletal class deformity will be enabled in some cases.

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