Two-Plate Splintless Repositioning in Bimaxillary Surgery: Accuracy and Influence of Segmental Osteotomies in a Consecutive Single-Centre Cohort.

Background/Objectives: The primary objective of this study was to evaluate the accuracy of maxillary repositioning using a two-plate patient-specific osteosynthesis system. The secondary objective was to determine whether accuracy is influenced by the number of maxillary segments. Methods: A retrospective single-centre cohort study was conducted on patients undergoing bimaxillary orthognathic surgery with a maxilla-first two-plate PSO system. Virtual Surgical Planning was performed based on the Cone-Beam Computed Tomography (CBCT) data of the patient, with patient-specific plates being designed and manufactured accordingly. Postoperative CBCT scans (7-10 days post-op) were registered to the preoperative plan, and deviations in translation and rotation between the plan and results were determined. Sub-group analyses were performed on one-, two- and three-segment maxillary osteotomy patient groups. Results: The inclusion criteria were met by 61 patients, of whom 47 were included for analysis (mean age 27.9 ± 9.4 years). Sub-millimetre median translational accuracies were found: anteroposterior 0.7 mm, transverse 0.4 mm, vertical 0.6 mm. The median rotational deviations were ≤1° for yaw and roll, and 1.6° for pitch. Accuracy was consistent across the one-, two-, and three-segment osteotomy groups. Conclusions: The two-plate PSO system is clinically accurate in bimaxillary surgery. There is no significant difference in accuracy between one-piece and segmental osteotomies of the maxilla when using the two-plate system.