Accuracy of β-tricalcium phosphate gap patient-specific implants in chin osteotomies: a pilot validation study

The objective was to evaluate the accuracy of patient-specific surgical cutting chin guides, patient-specific implant (PSI) chin plates, and β-tricalcium phosphate (β-TCP) gap patient-specific implants used in chin osteotomy by comparing their planned and postoperative positions. In addition, the reproducibility of the measurement method was assessed using intraclass correlation coefficients. Orthognathic patients requiring a chin osteotomy were included in the study. Preoperative virtual surgical planning was fused with postoperative cone-beam computed tomography imaging obtained 4 weeks after surgery. The planned and postoperative positions of the bony chin, PSI chin plate, and β-TCP gap-PSI were compared in terms of translational and rotational deviations. Reproducibility was assessed by two observers who repeated all measurements in two separate sessions. Ten patients were included in this pilot validation study. The mean deviation of the repositioned bony chin segment, the PSI chin plate, and β-TCP gap-PSI was <0.5 mm in the anteroposterior, vertical, and left-right directions. Rotational discrepancies were <1° for pitch, yaw, and roll, except for the pitch deviation of the β-TCP gap-PSI, which was 1.7°. Reliability ranged from moderate to excellent. The combination of patient-specific cutting guides, PSI chin plates, and β-TCP gap-PSIs allowed transfer of the virtual genioplasty plan with limited positional deviation in this pilot study. Further studies with larger samples and longer follow-up are required to assess β-TCP graft integration and clinical outcomes.