OBJECTIVES: The development of 3D computer-assisted technologies over the past years has led to vast improvements in orthognathic surgery. The aim of the present study was to evaluate differences in maxillary position between 3D virtual surgical planning (VSP) and surgical results. MATERIALS AND METHODS: We assessed data from 25 patients who underwent bimaxillary non-segmented orthognathic surgery with 3D VSP. Each patient underwent a postoperative CT scan within 40 days after surgery. We compared the STL (Standard Triangulation Language) file from the VSP with that obtained from the postoperative CT. RESULTS: According to our comparative analysis, the postoperative and VSP 3D models did not statistically differ. The Lin concordance correlation coefficient was always >
0.95 for each landmark, but in 21 patients (84 % of the sample) we identified at least one point with a difference of more than 1.5 mm between the postoperative and VSP 3D model on at least one axis. The most frequently observed differences corresponded to sagittal translation and pitch rotation. CONCLUSIONS: An intraoperative clinical and aesthetic evaluation of the consequences of bone movements on patient face is strongly recommended, also when we use VSP because we may have clinically significant differences from the planning.