Abstract
The purpose of this study was to evaluate postoperative changes of the frontal facial soft and hard tissues and to clarify the limit of treatment in patients with facial asymmetry who had undergone only sagittal splitting ramus osteotomy.
Method: The subjects were 21 adult jaw deformity patients with facial asymmetry, and a pair of pretreatment and postoperative (more than 6 months after operation) standardized frontal facial photos and postero-anterior cephalograms were used to evaluate the improvement of facial symmetry. For quantitative evaluation of the facial photos, the patient's FH plane and the plane of the floor were set up in parallel, and the head was fixed firmly by a ear rod. We measured the soft tissue Menton deviation angle and distance, the lip tilt angle and the facial mandibular plane tilt angle on the standardized frontal facial photos. Next, we measured the hard tissue Menton deviation angle, the occlusal plane tilt angle and the mandibular plane tilt angle on the postero-anterior cephalograms. Hard and soft tissue changes were statistically evaluated.
Result: The soft tissue Menton deviation angle (4.4 ± 1.2°) and distance (9.1 ± 2.8mm) significantly decreased (2.0 ± 1.7° and 4.2 ± 3.4mm) after operation. The lip tilt angle (3.8 ± 2.3°) and the facial mandibular plane tilt angle (2.7 ± 3.1°) also significantly decreased (1.9 ± 1.9° and 1.4 ± 2.9°) after operation. Hard tissue Menton deviation angle (4.5 ± 1.8°) significantly decreased (2.6 ± 1.3°) after operation. The occlusal plane tilt angle (2.1 ± 3.3°) and the mandibular plane tilt angle (2.4 ± 3.3°) slightly decreased (2.0 ± 2.9° and 1.4 ± 3.4°) but were not statistically significant. According to regression analysis of the cases whose angle between the soft tissue facial midline and the soft tissue Menton was less than 4.0°, and also whose angle between the hard tissue facial midline and the Menton was less than 3.2°, the soft tissue Menton deviation was improved to a normal range. However, in those cases whose angle exceeded 4.0° and 3.2°, the soft tissue Menton could not be corrected within the normal range. Therefore, in such cases, after thorough examination of maxillary deflection against the skull and the mandibular deformation itself, which cannot be detected by cephalogram, two-jaw surgery, genioplasty and mandibular angle plastic surgery will be necessary.
