Enhancing the accuracy of genioplasty using mixed reality and computer-aided design/manufacturing: a randomized controlled trial.

[BACKGROUND] Genioplasty is performed as part of orthognathic surgery to correct jaw deformities. This procedure presents challenges in terms of osteosynthesis accuracy. This study aimed to evaluate the precision of preoperative planning in genioplasty using computer-aided design/computer-aided manufacturing (CAD/CAM) with three-dimensional (3D) printable biomaterials and mixed reality (MR) technology with a head-mounted display (Microsoft HoloLens 2) and a registration marker.

[METHODS] Twenty-six patients underwent genioplasty using either only CAD/CAM devices (control group, n=10) or CAD/CAM with additional MR technology (experimental group, n=16). CAD/CAM devices were created based on virtual surgical planning (VSP), and MR holograms created based on VSP data were projected onto the surgical area using Microsoft HoloLens 2. After surgery, the planned model was compared with the postoperative computed tomography (CT) image, measuring the 3D surface and the differences in position and rotation using the root mean square deviation (RMSD) and Bland-Altman's method. Both analyses are blinded.

[RESULTS] The average 3D surface analysis errors within 2 mm ranged between 62.20-100.00% (control group) and 99.30-100.00% (experimental group), with mean errors of 92.12% and 99.81%, respectively. Errors within 1 mm ranged between 28.50-98.90% (control group) and 55.10-99.6% (experimental group) with mean errors of 67.36% and 85.60%, respectively. The largest RMSDs were 1.20 mm in the anteroposterior direction and 6.78° in pitch orientation for the experimental group and 1.78 mm in the anteroposterior direction and 6.04° in pitch orientation for the control group. A statistically significant difference between the two groups was observed for errors measured within 1 mm (P=0.047) and for yaw (P=0.003). No postoperative complications were observed in either group.

[CONCLUSIONS] Using CAD/CAM with additional MR technology in genioplasty improved the repositioning accuracy of the chin bone fragment and plate placement, with statistically significant improvements in specific spatial directions. This combination of CAD/CAM and MR technology allows for intraoperative spatial verification of fragment movement according to preoperative VSP, which significantly contributes surgical precision.