Accuracy of Guide-Free, Mixed Reality-Assisted Patient Specific Implant Fixation for Maxillary Repositioning: A Cohort Study.

OBJECTIVE: To develop a mixed reality (MR)-assisted, guide-free workflow for patient-specific implant (PSI)-based maxillary fixation and evaluate its positioning equivalence and procedural efficiency relative to conventional guide-assisted PSI fixation. METHODS: In this non-randomized cohort study, 28 patients undergoing Le Fort I osteotomy independently selected their preferred workflow after receiving detailed information on both approaches and were categorized according to the workflow received. MR navigation guided osteotomy lines and screw-hole positioning in the MR-assisted group, whereas conventional surgical guides were used in the guide-assisted group. Equivalence was assessed using two one-sided tests (TOST), with margins of ±0.5 mm for translational and ±1.0° for rotational outcomes. RESULTS: All 90% confidence intervals (CIs) for between-group differences in translational and rotational positioning errors were entirely within the prespecified equivalence margins, supporting statistical equivalence within these bounds. Small directional offsets were observed for A-X (mean difference, -0.206 mm), UL6-Y (0.168 mm; 90% CI, 0.070-0.267 mm), and yaw (0.159°; 90% CI, 0.017-0.302°), although all remained within the equivalence margins. Preoperative preparation time and mean Le Fort I segment time were reduced in the MR-assisted group, which also required fewer intraoperative adjustments (2.29 ± 1.49 vs. 4.29 ± 1.20; P = 0.0006). CONCLUSION: MR-assisted, guide-free PSI fixation showed positioning outcomes statistically equivalent to guide-assisted fixation within the prespecified margins and was associated with greater procedural efficiency. CLINICAL RELEVANCE: MR-assisted, guide-free PSI fixation may reduce reliance on surgical guides while maintaining between-workflow positioning differences within prespecified equivalence bounds.