1989 Volume 35 Issue 1 Pages 46-62
Two-and three-dimensional postoperative predictions utilizing the computer system were evaluated for exactness from the amount of aberration of the prediction in all measuring points on 36 cases with mandibular deformities operated by sagittal splitting osteotomy of the mandibular ramus. Lateral and frontal head films taken by the method of applying occlusal splints and plaster casts of the mandibular dental arch already explained in the second part were made material in this study. The following result were obtained:
1. About the prediction of hard tissue, computer graphic prediction of the profile (aberration: average 0.3-1.2mm) was superior to prediction by the conventional paper surgery with statistical significance, though it was a little inferior to that by the modified method (referring to the second part). The prediction of soft tissue was made on the basis of the results of the third part and satisfying results (aberration: average 0.5 mm) were obtained.
2. In the three-dimensional computer graphic prediction, a little aberration (average: 0.5-1.6mm) of prediction on frontal hard tissue was observed.
3. The position of point B and Pogonion must be decided also in three-dimensional coordinates about the postoperative prediction of mandibular deformity. It was possible to institute those measuring points on the basis of the results of the first part. In addition, the method of point B plasty on genioectomy was introduced.
4. Superimposing of frontal head films was considered possible indirectly, utilizing the computer system.
5. The method of three-dimensional computer graphic prediction seemed to include some problems from multiple points of view.
