Comparison of the Accuracy of Maxillary Positioning With Interim Splints Versus Patient-Specific Guides and Plates in Executing a Virtual Bimaxillary Surgical Plan

An extension of digital technology is to provide patient-specific hardware to reposition the first jaw in a bimaxillary case without the use of an intermediate splint. The purpose of our study was to determine if there were significant differences in maxillary repositioning using interim splints versus patient-specific guides and implants (PSIs) in executing a bimaxillary virtual surgical plan (VSP).This is a retrospective cohort study of patients who underwent bimaxillary orthognathic surgery with interim splints or PSIs planned with VSP at our institution. The difference in maxillary positions from the VSP to the postoperative cone-beam computed tomography (CBCT) was evaluated in both groups. The primary predictor variable was the method by which the maxilla was repositioned (interim splint vs PSI). The primary outcome variable was the postoperative 3D position of the maxillary incisors and right and left first molars in the anteroposterior, transverse, and vertical dimensions. Differences in the planned and postoperative positions of the above landmarks in all three planes of space between the two groups were statistically analyzed.A total of 82 patients were included. 13 patients had their maxillae repositioned with an interim splint between the unoperated mandible and the mobile maxilla, and 69 patients had their maxilla repositioned using custom drill/cutting guides and a PSI. The mean difference between the planned and actual position of the maxilla in the PSI group was smaller than in the splint group. In the PSI group alone, vertical changes were accurate whether the maxilla was being superiorly or inferiorly repositioned.The use of a PSI provides more accurate maxillary repositioning during bimaxillary surgery than the use of an interim splint.