Purpose: The purpose of this study was to compare the morphologic changes of the upper airway space in Class III patients underwent mandibuler set back or bimaxillary surgery (maxillary advancement and mandibular setback) by computed tomography at 2 levels: soft palate and base of tongue Materials and Methods:The sample is consisted of 47 patients in 2 groups who had been diagnosed with Class III skeletal deformities and had been treated by mandibular setback or bimaxillary surgery (maxillary advancement and mandibular setback).Anteroposterior, lateral, cross sectional area dimensions of the airway at the level of soft palate and base of tongue was measured pre-and postoperatively on computed tomography images.Results: However, anteroposterior dimensions of the airway decreased in both groups (p<.0001), the reduction was significantly less in cases treated with bimaxillary surgery (p<.05). In mandibular setback surgery group, the cross sectional area of the airway decreased significantly (p<.001) Although, the cross sectional area of the airway decrease in bimaxillary surgery group, the reduction was not statistically significant (p>.05).Conclusions: This study suggested that bimaxillary surgery could prevent narrowing of the upper airway in the correction of Class III deformities rather than mandibular setback surgery .

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Cephalometric studies have revealed that there were significant sexual differences in the size of the pharyngeal airway space. The purpose of this study was investigate and compare the morphologic changes after mandibular setback or two jaws surgery on pharyngeal airway between females and males with computed tomography. The sample is consisted of 34 female and 13 male patients in 4 groups who had been diagnosed with Class III skeletal deformities

Results. There was no significant difference in reduction in mandibular length between SSRO alone and SSRO with Le Fort I on the axial view of a 3D CT. There were no significant differences between pre-and postoperative horizontal changes in the condylar long axis or in the antero-posterior and medio-lateral displacement of the condylar head, although the length of the proximal segment in SSRO with Le Fort I osteotomy was significantly shorter than in SSRO alone (P<0.05). Conclusion.These results suggest that the use of a bent plate for SSRO does not change preoperative angle or position significantly in setback surgery, regardless of the addition of Le Fort I osteotomy.

2 AbstractPurpose: The purpose of this study was to evaluate the differences in the recovery of maximum mandibular opening (MMO), and the relationship between MMO and the maxillomandibular fixation (MMF) period after sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO), with and without Le Fort I osteotomy. Subjects and Methods:Sixty-eight patients with diagnosed mandibular prognathism with or without asymmetry were divided into four groups (SSRO, IVRO, SSRO with Le Fort I osteotomy, and IVRO with Le Fort I osteotomy). MMO and the MMF period were measured preoperatively and at 1-, 3-, 6-, 12-, and 18-months after surgery. The differences among surgical procedures and the relationship between MMO and the MMF period were examined statistically. Results:In relation to time-dependent changes in MMO, there were no significant differences among the groups. There were significant positive correlations between MMO and the MMF period from 1 month to 6 months after surgery. However, there were no significant correlations at 12-and 18-months after surgery. Conclusion:This study suggests that there were no significant differences between single-jaw surgery and double-jaw surgery in terms of postoperative time-dependent changes in the recovery of MMO. However, the MMF period was associated with the recovery of MMO.3

Purpose: The purpose of this study was to examine the changes in the chewing rhythm before and after mandibular ramus osteotomy for patients with prognathism with and without asymmetry.Patients and Methods: twelve men and 22 women with mandibular prognathism were divided into groups on the basis of symmetry and osteotomy procedure. Preoperative and postoperative duration of chewing cycle were recorded. The duration of chewing cycle and coefficient variation were compared between groups and the differences were analyzed statistically.Results: No significant differences in each of three phases of chewing cycle and total duration were found between groups on the basis of symmetry or osteotomy procedure.However, in the coefficienct of variation, there were significant differences between pre and post operation in the undeviated side in asymmetry group (P=0.0037) and SSRO group (P=0.0166). Conclusion:This study suggests that surgical orthodontic treatment does not significantly change the duration of chewing cycle.

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