Half the Morbidity: Unilateral Sagittal Split Osteotomy

Abstract

The Bilateral Sagittal Split Osteotomy (BSSO), first described by Trauner and Obwegeser in 1957, has undergone several modifications over the years, including those proposed by Dal Pont in 1961 and Obwegeser in 1964. The Unilateral Sagittal Split Osteotomy (USSO), which involves surgery on one side of the mandible, offers a less invasive alternative that carries half the risk of BSSO. Aim(s): This retrospective case series aims to evaluate the outcomes of 18 patients undergoing USSO for the correction of dentofacial malocclusions and mandibular asymmetry. Method(s): The cohort included patients who underwent USSO advancement or setback with either a Le Fort I maxillary advancement or genioplasty from 2018 to 2024 at The Royal London Hospital and Whipps Cross Hospital. These patients presented with maxillary hypoplasia, mandibular prognathism, reverse overjet, increased vertical dimensions, Class I and III malocclusions, and mandibular asymmetry. The post-operative outcomes measured were occlusion, evidence of temporomandibular joint dysfunction (TMJD), paraesthesia, mouth opening, and relapse. Results and Conclusion(s): At follow-ups conducted at one, two, three, four, and five years, 14 patients had achieved a stable occlusion, 15 patients had no paraesthesia, no patients showed evidence of TMJD resulting from the procedure, nor any evidence of relapse. Inter-incisal distances measured between 34 mm and 40 mm. In conclusion, USSO offers a conservative and effective alternative to BSSO, with a reduced risk profile and favorable clinical outcomes. By minimizing surgical trauma and reducing the likelihood of complications such as TMJD and paraesthesia, USSO may represent a favorable approach for managing dentofacial malocclusions and mandibular asymmetry.Copyright © 2025