Clinical validation of the virtual splint registration workflow for craniomaxillofacial surgery

Accurate registration is vital to transfer the virtual surgical plan during surgery. This study's goal was to present and clinically validate a virtual splint registration workflow. Ten dentate patients requiring revision surgery were included. Specific inclusion criterion for this study was the presence of at least two osteosynthesis screws on the orbital rim from a previous surgery. Dedicated orthognathic surgery software was used to fuse the maxillary dental scan with the computed tomography and generate a dental splint, which was imported into the navigation software and augmented with fiducial markers. Registration points were indicated virtually and the augmented splint was three-dimensionally printed. Intraoperatively, the splint was fitted on the maxillary dentition and the fiducial markers were used for registration. Accuracy of the registration procedure was quantified by calculating the difference between the landmarks acquired by indicating the pre-existing osteosynthesis material with the navigation pointer and in the virtual planning software. After acquisition of the landmarks, the screws were removed and surgery proceeded according to plan. A median target registration error of 1.53 mm was found. The advantages of the virtual splint registration workflow are that it does not require extensive computer-aided design skills or repeated preoperative imaging, and is non-invasive.