Comparison of the neurosensory disturbances after Bilateral sagittal split osteotomy and modified oblique subcondylar osteotomy in set back of mandible

Abstract

Comparison of the neurosensory disturbances after Bilateral Sagittal Split Osteotomy and Modified Oblique Subcondylar Osteotomy in set back of mandibul. Introduction: Modified Oblique SubCondylar Osteotomy (MOSCO) , a modification of IntraOral vertical Ramus Osteotomy (IVRO), is a surgical procedure for set back of mandibule. There has been no comprehensive study on this prosedure. In this study we compared inferior alveolar nerve (IAN) neurosensory disturbances (NSD) after Bilateral Sagittal Split Osteotomy (BSSO) and MOSCO. Method: In the clinical trial, 34 patients with mandibular prognathism selected and listed randomly in two groups that underwent two surgical procedures separately ,BSSO and MOSCO .Sensation quality assessed subjectively and objectively (two-point discrimination) in the lower lips before and after surgery . Data were analyzed by discrementional statistical methods chi-square test and T-test. Results were considered to be statistically significant at 5% critical level .(P<0.05). Results: NSDs following BSSO at first week , first month ,third month and sixth month were subsequently 100% , 76.5% , 64.7% and 29.4% on the right sides ; 100% , 100% , 88.2% and 74.4% on the left sides .Incidence of NSDs following BSSO on the right sides were less than on the left sides and it seems dependent on surgeon's dominant hand. None of patients who underwent MOSCO experienced NSD. Before the surgeries women were more sensitive than men in two-point discrimination test. But after MOSCO there were no difference with before surgery. Conclusion: NSD following MOSCO was zero whereas BSSO cause significant incidence of NSD. Incidence of NSD after BSSO depends on the side of surgery, and sexuality.