Changes in Condylar Position Within 12 Months After Bilateral Sagittal Split Ramus Osteotomy With and Without Le Fort I Osteotomy by Using Cone-Beam Computed Tomography

Abstract

This study aimed to evaluate the condylar position changes in 12 months after bilateral sagittal split ramus osteotomy (BSSO) with and without a Le Fort I osteotomy in patients with Class III malocclusion and the influence of the 2 surgical approaches on the condylar position.In this prospective cohort study, patients with skeletal Class III malocclusion who underwent orthognathic surgery between 2017 and 2019 were included. The main predictive variable is the effect of increasing Le Fort I osteotomy on condyle position, which is divided into BSSO-only group and BSSO + Le Fort I osteotomy group. The main outcome variables were the displacement of the condylar head and the rotation/inclination of the condylar long axis before and after surgery. Other study variables were according to the degree of asymmetry of the left and right side of the mandible, the measured values of both sides were divided into mandibular deviation and nondeviation. The cone-beam volumetric imaging images were obtained before surgery (T1) and immediately after surgery (T2), 3 months (T3), 6 months (T4), and 12 months (T5) after surgery by computerized tomography (CT). One-way ANOVA and Tukey test was used for correlation analysis. The p-value is set to 0.05.Twenty-four adult patients diagnosed with skeletal Class III malocclusion were included in this study, 12 patients (male/female = 6:6, mean age 21.8 years) who underwent BSSO + Le Fort I osteotomy and 12 patients (male/female = 6:6, mean age 19.8 years) who underwent BSSO-only. The position of the bilateral condylar head in both surgery groups was adjusted continuously during the 12 months after the operation. Immediately and 12 months after surgery, both sides of the condylar long axis in the BSSO with Le Fort I osteotomy group and the BSSO-only surgery group rotated inward, tilted forward, and tilted inward. In the BSSO with Le Fort I osteotomy group, the rotation and tilt angle changes of the condylar long axis on both sides were stable 6 months after surgery.The addition of Le Fort I osteotomy did not significantly change the rotation and tilt direction of the condylar long axis and could accelerate the stability of the condylar long axis after BSSO surgery.