Clinical Accuracy and Postoperative Stability of 3D-Printed Surgical Guides in Bimaxillary Orthognathic Surgery: A Prospective Evaluation.

[BACKGROUND] The success of virtual surgical planning (VSP) in bimaxillary orthognathic surgery relies on the precise translation of digital plans into operative outcomes. Although computer-assisted design and 3D-printed surgical guides are increasingly adopted to improve surgical accuracy, clinical data on the performance of systems employing Mimics software-particularly concerning long-term postoperative stability-remain scarce.

[METHODS] Twelve consecutive patients undergoing bimaxillary surgery between July 2023 and September 2024 were prospectively enrolled. Preoperative cone-beam computed tomography (CBCT) and dental models were integrated into Mimics software for multimodal registration, 3D reconstruction, and VSP. Surgical procedures included Le Fort I osteotomy, bilateral sagittal split osteotomy (BSSO), and genioplasty. A fully customized 3D-printed surgical guide system, including osteotomy guides, repositioning guides, and occlusal splints was employed. Postoperative CBCT scans were acquired at 10 days (T1), 1 month (T2), 3 months (T3), and 6 months (T4). CBCT scans from T1 and T4 were analyzed in 3-Matic to quantify 3D deviation. Clinical success was defined as linear deviations ≤ 1.5 mm and angular deviations ≤ 2°. Longitudinal comparisons of CBCT datasets across all postoperative intervals (T1-T4) were performed to assess stability. Statistical analysis was conducted using paired t-tests in SPSS 26.0 (α= 0.05).

[RESULTS] Mean linear deviation was 1.34 ± 0.28 mm at T1 and 1.17 ± 0.22 mm at T4, while angular deviation was 1.95° ± 0.41°and 1.81° ± 0.35°, respectively. All values were within the predefined clinical thresholds. Maxillary landmarks (ANS, A-point, dental cusps) remained stable throughout the observation period (P > 0.05), whereas mandibular landmarks (B-point, pogonion, menton, dental cusps) demonstrated statistically significant progressive stabilization (P < 0.05). Directional analysis revealed the highest accuracy in the horizontal plane (0.58 ± 0.16 mm) and the greatest deviations in the sagittal direction (1.71 ± 0.61 mm at T4).

[CONCLUSIONS] The 3D-printed digital guide system achieved clinically acceptable accuracy and demonstrated favorable postoperative stability. Maxillary skeletal landmarks exhibited superior precision compared to dental references. Notably, mandibular structures showed significant positional improvement over time, suggesting distinct healing dynamics between the jaws. All observed deviations fell within published tolerances, validating the system's reliability for clinical application in orthognathic surgery.

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