Controlling maxillary vertical repositioning with virtual surgical planning to eliminate the triangulation effect

Accurate control of maxillary vertical repositioning remains challenging in splint-based orthognathic surgery when large anteroposterior movements introduce a triangulation-related measurement effect. This technical note describes a virtual surgical planning (VSP)-based method to calculate the triangulation-adjusted change in the medial canthus-incisor distance and transfer it to the operating room. The distance is measured in VSP before and after the planned movements using identical landmarks, and the difference is used as the intraoperative caliper adjustment target during maxillary repositioning. This workflow provides a practical way to reduce measurement bias and improve fidelity between planning and execution.