Surgical Accuracy of Maxilla-First Orthognathic Surgery That Tooth Interference OCCURS After Maxillary Movement

This study aimed to compare the accuracy of maxillary repositioning using 2 types of CAD/CAM-fabricated splints (the traditional intermediate wafer and a customized maxillary repositioning guide) with a specific focus on dental interferences between the upper and lower arches during maxilla-first orthognathic surgery. Patients who exhibited dental interferences after maxillary movement during surgical simulation were enrolled. The intermediate wafer was designed to virtually open the patient's mandible, thereby avoiding tooth interference, whereas the guide was created independently of dental contacts. Accuracy was assessed by superimposing postoperative cone-beam computed tomography images onto preoperative virtual simulation data. Eighteen patients were included, with 13 in the guide group and 5 in the wafer group. The absolute error distance was larger in the wafer group for all landmarks. Errors exceeding 2 and 1 mm were more frequent in the wafer group than in the guide group (P=0.01 and 0.43, respectively). However, no significant differences were found between groups for three-dimensional error distances at each reference point, and no consistent error direction was observed. The customized maxillary repositioning guide demonstrated superior accuracy within the 2 mm discrepancy range compared with the intermediate wafer, especially in situations requiring mandibular position modification for intermediate wafer fabrication.