The Evaluation of the Positional Change of the Mandibular Condyle after Bilateral Sagittal Split Ramus Osteotomy using Three Dimensional Computed Tomography in Skeletal Class Iii Patients

ABSTRACT

PURPOSE: This study was performed to evaluate three-dimensional positional change of the condyle using 3D CT after bilateral sagittal split ramus osteotomy (BSSRO) in skeletal class III patients. PATIENTS AND METHODS: Nine patients who underwent BSSRO for mandibular set-back in skeletal class III malocclusion without facial asymmetry were examined. Miniplates were used for the fixation after BSSRO. 3-D CT was taken before, immediately after, and 6 months after undergoing BSSRO. After creating 3D-CT images using V-works 4.0(TM) program, axial plane, coronal plane, < sagittal plane were configured. Three dimensional positional change, from each plane to the condyle, of the nine patients was measured before, immediately after, and 6 months after undergoing BSSRO. RESULTS: 1. The mean value of mandibular set-back for nine mandibular prognathism patients was 7.36 mm (+/- 2.42 mm). 2. In the axial view, condyle is rotated inward immediately after BSSRO (p < 0.05), comparing with preoperative but outward 6 months after BSSRO comparing with postoperative (p < 0.05). 3. In the axial view, condyle is moved laterally immediately after BSSRO (p < 0.05), comparing with preoperative but regressed 6 months after BSSRO comparing with preoperative (p < 0.05). 4. In the frontal < coronal view, there is changed immediately after and 6 months after BSSRO, comparing with preoperative but no statistical difference. CONCLUSION: These results indicate that three-dimensional positional change of the condyle in skeletal class III patients is observed lateral displacement < inward rotation immediate after BSSRO, but the condyle in 6 months after BSSRO tends to regress to preoperative position.