Maxillary Stability After Le Fort I Osteotomy With 1.5 mm Microplate Fixation: A Retrospective Study.

Background: Le Fort I osteotomy is commonly performed to correct maxillary deformities, with most surgeons using 4 miniplates (2.0 mm) for fixation. However, limited evidence exists regarding postoperative skeletal stability when using smaller microplates (1.5 mm). This study aimed to evaluate the 3-dimensional skeletal stability of the maxilla following Le Fort I osteotomy fixed with 1.5-mm microplates in orthognathic surgery patients at the Faculty of Dentistry, Mahidol University.

Methods: A retrospective cohort study was conducted on 30 patients (21 women, 9 men; mean age 26.8 ± 5.7 y) who underwent bimaxillary osteotomies by the same surgeon. Postoperative skeletal changes were assessed using 3-dimensional virtual models generated from cone-beam computed tomography scans taken 1 week (T1) and 6 months (T2) after surgery. Superimposition of these models using an iterative closest point algorithm enabled the measurement of maxillary stability. The root mean square of point-to-point distances between models and positional differences at 9 anatomical landmarks were analyzed.

Results: All patients demonstrated satisfactory surgical outcomes. The mean root mean square value between superimposed models was 0.8019 mm (SD 0.413 mm), within clinically acceptable limits (≤2 mm). Differences in bone surface coordinates were within ±0.5 mm, with a mean distance change of -0.182 ± 0.2 mm. No significant surgical relapse was observed at any reference point after 6 months.

Conclusions: This is a retrospective study assessing maxillary stability with 1.5-mm microplates. The results indicate that 4-point microplate fixation offers stable and predictable postoperative outcomes in appropriately selected Le Fort I osteotomy cases.