Virtual Orthognathic Surgery: A Retrospective 3D Analysis of Surgical Planning vs. Postoperative Outcomes

Abstract

Objective: Orthognathic surgery addresses facial deformities by improving both function and aesthetics, with its success relying heavily on accurate planning. This study aimed to assess the long-term accuracy of virtual surgical planning (VSP) by comparing three-dimensional (3D) preoperative virtual models with actual postoperative outcomes and identifying regions prone to deviation. Methods: A retrospective study was conducted and approved by the Ethics Committee of Bezmialem Vakıf University. Patients who underwent bimaxillary surgery for Class II or III malocclusion and had postoperative computed tomography scans ≥6 months later were included. VSP was performed using NemoFab software. Standardized Le Fort I and bilateral sagittal split ramus osteotomies were conducted. The preoperative virtual planning model and the postoperative surgical model were aligned using surface-based registration in 3-matic and analyzed in Mimics. Linear and directional (sagittal, coronal, axial) deviations were measured at cephalometric landmarks, and 3D color-coded deviation maps were generated with a ±2 mm threshold. Distance differences between 15 cephalometric points on preoperative planning and postoperative models were statistically analyzed using a one-sample t-test. Results: Forty-two patients (aged between 18 and 40) were included. The mean deviation was 2.19±0.82 mm. Significant deviations (>2 mm) were observed at anterior nasal spine (ANS) and posterior nasal spine (PNS) points, and for maxillary mean deviation, while mean deviations in axial, coronal and sagittal planes were significantly below 2 mm. No significant differences were observed based on sex, skeletal class, or surgical sequence. Most discrepancies occurred in the anterior maxilla, chin, and posterior mandible. Preoperative asymmetry and pogonion deviation were not predictive of discrepancies. Intraclass correlation coefficient values >0.90 confirmed measurement reliability. Conclusion: VSP shows high overall accuracy; however, ANS and PNS remain prone to deviation, warranting further investigation in larger studies.