Journal of Dental Medicine

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 Statement of Problem:The choung osteotomy (Intraoral Vertico- Sagittal Ramus Osteotomy) has developed since 1992 in the treatment of mandibular prognathism. In IVSRO, osteotomy plane is theoretically parallel to the original sagittal plane and thereby attempting to decrease the incidence of condylar dispacement. This osteotomy designed additionally to decrease neurosensory disturbances.
Purpose: The aim of this study was to evaluate the incidence of neurosensory deficit and condylar displacement with IVSRO and Sagittal Split Ramus Osteotomy (SSRO).
Materials and Methods: In this study, mandibular set back surgery was accomplished upon 7 patients by choung osteotomy. In addition to choung osteotomy, in 2 patients Lefort 1 osteomy was performed for maxillary protrusion and for 2 other patients, chain surgery was performed. Variables such as the neurosensory disturbances of inferior alveolar nerve and condylar displacement following choung osteotomy were investigated. All the patients were followed up one year after osteotomy. OPG, Lateral Cephalogram and Submentovertex radiographies were take pre and postoperatively for all patients.
Results: No statistically significant differences were found in condylar displacement (P>0.5). However, Mc Nemar analysis showed significant difference of neurosensory deficit between IVSRO and SSRO (P=0.001).
Conclusion: It is suggested that choung osteotomy is a safe procedure for mandibular surgery.

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Background and Aim: Proximal segment movements following different methods of ramus osteotomy is one of the undesired consequences of orthognathic surgery. Theoretically, it seems that intraoral verticosagittal ramus osteotomy can minimize the movement of proximal segment. In this study, changes in intergonial distance and ramus flaring angles were evaluated and compared in transverse plane after mandibular set back by two osteotomy techniques.

Materials and Methods: In this randomized clinical trial 20 patients with mandibular prognathism without any asymmetry were selected and divided into two groups of 10 each.One group was treated by bilateral sagittal split ramus osteotomy and the other by intraoral verticosagittal ramus osteotomy technique. Intergonial width and inner ramal angle in transverse plane were measured on radiographs before and 1 and 12 weeks post surgery . Data were analyzed using covariance test with P<0.05 as the level of significance.

Results: Changes of intergonial distance and interramal angle in each group were significant after 1 and 12 weeks after surgery. No statistically significant difference was observed between the two studied groups.

Conclusion: According to the results of this study, there is no difference between bilateral sagittal split and intraoral verticosagittal ramus osteotomy techniques regarding mandibular width and ramus flaring changes.