Recent studies of Bimaxillary Orthognathic Surgery (BMOS) with Le Fort I osteotomy have attempted to obtain precise results consistent with preoperative virtual surgical simulation by using computer-aided design/computer-aided manufacturing (CAD/CAM)-generated wafers. In these studies, intermediate CAD/CAM wafers for maxillary repositioning were designed using preoperative simulation software for orthognathic surgery and prepared using rapid prototyping technology. However, these studies could not provide clear evidence that the novel method of maxillary repositioning using CAD/CAM wafers was more accurate than those using conventional methods. In the double-splint method of BMOS, intraoperative maxillary repositioning is affected by movements of the temporomandibular joint, because intermediates of the maxilla segments are anchored to the mandible. Since the movements of the temporomandibular joint are unstable under general anesthesia, the repositioning of the maxilla depending on movements of the mandible may cause inaccuracies. Thus, precise repositioning consistent with the preoperative simulation of the maxilla to the designed position may be difficult to achieve, even if CAD/CAM wafers are used. To solve this issue in Le Fort I osteotomy, we have previously suggested a novel methodology that consisted of maxillary repositioning using a CAD/CAM wafer and intraoperative real-time confirmation of the three-dimensional (3-D) positional information with a navigation system. However, whether the accuracy can be maintained when maxillary repositioning using a CAD/CAM wafer and an intraoperative navigation system is performed in more complicated surgery such as segmental Le Fort I is unclear. In this pilot study involving patients who underwent bimaxillary orthognathic surgery with segmental Le Fort I osteotomy, the precision of maxillary repositioning was evaluated on the basis of the hypothesis that maxillary repositioning reflecting preoperative virtual surgical simulation can be achieved using a CAD/CAM splint and an intraoperative navigation system. Six participants with jaw deformities who required BMOS incorporating segmental Le Fort I osteotomy were included. The preoperative simulation was performed using a three-dimensional skull model on the simulation software, and a wafer for maxillary repositioning was prepared by CAD/CAM. Using the CAD/CAM-generated wafer and intraoperative navigation system, the maxillary segments were repositioned to agree with virtual surgical planning. The ideal movements of the preoperative simulation were compared with the actual movements after the surgery, and the errors of the ideal movements with reference to the actual movements were evaluated three-dimensionally at seven evaluation points. The largest and smallest median errors calculated from the differences between the ideal and actual 3-D movements were, respectively, 0.65 mm at anterior nasal spine, 0.02 mm at posterior nasal spine. There is no significant difference was observed between ideal and actual movements in either 2-D and 3-D. The clinical accuracy of maxillary repositioning with the CAD/CAM wafer and an intraoperative navigation system in segmental Le Fort I osteotomy was revealed in the present study.

Regards,
Catherine
Journal Co-Ordinator
Journal of Orthodontics and Endodontics