Augmented Reality to Assist in the Diagnosis of Temporomandibular Joint Alterations

Augmented Reality (AR) is an increasingly prominent technology with diverse applications across various surgical disciplines. This study aims to develop and assess the feasibility of a novel AR application intended to aid surgeons in the clinical assessment of temporomandibular joint (TMJ) alterations necessitating surgical intervention. The application employs a multi-modality tracking approach, combining both marker-less and marker-based tracking techniques to concurrently track the fixed portion of the joint and the movable mandible involved in TMJ. For the marker-based tracking both a planar marker with a binary QR-code pattern and a cuboid marker that contains a unique QR-code pattern on each face were tested and compared. The AR application was implemented for the HoloLens 2 head-mounted display and validated on a healthy volunteer performing the TMJ task, i.e. the opening and closing of the mouth. During the task, video recordings from the HoloLens cameras captured the horizontal and vertical excursions of the jaw movements (TMJ movements) using virtual markers anchored to the AR-displayed virtual anatomies. For validation, the video-recorded TMJ movements during AR viewing were compared with standard kinesiographic acquisitions. The findings demonstrated the consistency between the AR-derived trajectories and the kinesiography curves, especially when using the cubic Multi Target tracker to follow the moving mandible. Finally, the AR application was experienced on a patient and it was extremely useful for the surgeon to diagnose alterations in the normal kinematics of the TMJ. Future efforts should be addressed to minimize the bulkiness of the tracker and provide additional visual cues for surgeons.