Displacement of Proximal Segment after Sagittal Split Osteotomy--From 3D Image Analysis, Predictors to the Influence on Skeletal Stability and Outcome

Background and Purpose: Bilateral sagittal split osteotomy (BSSO) is the most favored surgical procedure for the treatment of mandibular prognathism. Despite of its popularity, improper positional change in the proximal segment from surgery may lead to malocclusion associated with the risk of early relapse and the development of temporomandibular disorders. We therefore aim to (1) identify the displacement of the proximal segment after BSSO asymmetric setback and its predictors, and (2) evaluate if the skeletal stability, skeletal outcome or temporomandibular joint symptoms is associated with the displacement. Methods: This is a cohort study using a new method of 3D image analysis through cone-beam computed tomography (CBCT). We plan to recruit 80 patients (age 18 years) with asymmetric Class III deformity who are scheduled for bimaxillary orthognathic surgery: monocortical screw fixation (MS group, n = 40) and bicortical screw fixation (BS group, n = 40). All subjects undergo CBCT before surgery, one week and 12 months after surgery. Images are analyzed to obtain position and displacement (6 degrees of freedom) of the maxilla and mandible (proximal and distal segments) after surgery. Data Analysis: Univariate and multivariate analyses will be performed. Statistical significance is assumed for a p value of less than 0.05.

Project ID:PC10408-1727
External Project ID:MOST104-2314-B182-045