The predictability of maxillary repositioning in LeFort I orthognathic surgery.

Our ability to predict the outcome of any orthognathic procedure relies on the surgeon's ability to accurately reproduce the desired skeletal movements and on our understanding of the soft tissue changes associated with those movements. The purpose of this retrospective study was to evaluate the surgical accuracy of maxillary repositioning by comparing the objectives obtained from cephalometric prediction tracings with the actual skeletal changes achieved during maxillary and maxillomandibular procedures. The sample consisted of 46 patients from the files of 1 orthodontist. Presurgical and immediately postsurgical cephalometric radiographs were digitized, and the original surgical prediction was reproduced with Dentofacial Planner (Dentofacial Software, Toronto, Ontario, Canada) software. Vertical and horizontal measurements to several skeletal landmarks were used to assess the differences between the predicted maxillary position and the actual maxillary postsurgical position. Statistical differences were found for some measurements, particularly those related to the vertical placement of the posterior maxilla. Three variables were evaluated for their effect on the surgical discrepancies. The 2 surgeons with the most patients were evaluated and found to have differences in the direction of discrepancies but not the amount (absolute values). Significant differences were also found when evaluating surgical complexity (single-jaw vs bimaxillary procedures) and the direction of movement (impaction vs advancement) in direction only. To assess the overall fit of individual predictions, we calculated an average discrepancy for each patient; 80% of the actual results fell within 2 mm of the prediction, and 43% fell within 1 mm of the prediction.