Objective: This study aimed to examine the accuracy of computer-aided intraoperative navigation (Ci-Navi) in bimaxillary orthognathic surgery, by comparing preoperative planning and postoperative outcome. Methods: The study comprised 45 patients with congenital dentomaxillofacial deformities who were scheduled to undergo bimaxillary orthognathic surgery. Virtual bimaxillary orthognathic surgery was simulated using Mimics software. During the surgery, a Le Fort I osteotomy of the maxilla was performed using osteotomy guide plates. After the LeFort I osteotomy and bilateral sagittal split ramus osteotomy of the mandible, the mobilized maxilla and the distal mandibular segment were fixed using an occlusal splint, forming the maxillomandibular complex (MMC). Real-time Ci-Navi was used to lead the MMC in the designated direction. Osteoplasty of the inferior border of the mandible was performed using Ci-Navi when facial symmetry and skeletal harmony were of concern. Linear and angular distinctions between preoperative planning and postoperative outcome were calculated. Results: The mean linear difference was 0.79 mm (0.62 mm for the maxilla and 0.88 mm for the mandible); the overall mean angular difference was 1.20°. The observed difference of the upper incisor point to the Frankfort horizontal plane, midfacial sagittal plane, and coronal plane was <1 mm in 40 cases. Conclusions: This study demonstrated the role of Ci-Navi in the accurate positioning of bone segments during bimaxillary orthognathic surgery. Ci-Navi was found to be a reliable method to transfer the surgical plan during operation.

Keywords: Orthognathic surgery, Virtual surgery planning, Computer-assisted surgery, Intraoperative navigation