Markerless Augmented Reality Guidance System for Maxillofacial Surgery: An Omnidirectional Tracking Method.

Background and Aims: Surgeons still face challenges in transposing preoperatively planned osteotomies to the operating room for accurate navigation. Current cutting guide methods in maxillofacial surgery are costly, time-consuming, and invasive. Methods: This study introduces a novel markerless AR guidance system to replace physical cutting guides with digital holographic guides. Microsoft HoloLens 2 was used to track the patient's mandible in real-time without markers, providing automatic alignment. This approach allowed detection from any angle and remained reliable even when parts of the mandible were obstructed. Accuracy was assessed by measuring hologram registration errors, and usability was compared with the clinical gold standard, calculated using an EM sensor in an in-vitro study with eight surgeons. Results: The system achieved an average registration error of under 1.40 mm and a precision of 1.15 mm when measured against the clinical gold standard. Conclusion: The AR system provides a promising, less invasive, cost-effective alternative to traditional cutting guides in maxillofacial surgery, enhancing precision and efficiency.