Three-Dimensional Assessment of Maxillary Stability Using Customized Plates in Orthognathic Surgery: A Retrospective Cohort Study

Patient-specific implants (PSIs) in orthognathic surgery offer optimal intraoperative accuracy. However, evidence regarding their postoperative skeletal stability, specifically comparing distinct fixation designs and segmentation patterns, remains limited. We present a retrospective cohort study that evaluated 64 adult patients undergoing customized maxillary orthognathic surgery between January 2020 and June 2025. The primary predictor variables were fixation design (conventional customized plates vs. minimally invasive plates) and maxillary segmentation (monoblock vs. multisegmental). The outcome variable was 3D skeletal stability, measured as linear displacement between preoperative planning and 6-month postoperative imaging. Non-parametric tests compared displacements and clinical instability rates (defined as ≥2.0 mm). Mann–Whitney tests compared landmark displacements, Fisher’s exact tests compared proportions with ≥2.0 mm displacement, and ORs with 95% CIs were computed (α = 0.05). Analysis of 64 patients revealed that median displacement across landmarks ranged from 0.7 to 4.28 mm and 28.1% exhibited displacement ≥ 2.0 mm, primarily in molar and canine regions. While overall instability rates did not differ significantly between single-segment and multisegmental osteotomies (p = 0.28), multisegmental cases showed significantly higher displacement at the left canine (p = 0.027). Plate design was not associated with skeletal instability (p = 0.88), suggesting that minimally invasive plates provide comparable stability to conventional designs. Customized maxillary plates provide reliable postoperative stability with median displacements within clinically acceptable limits (<2 mm). Minimally invasive PSI designs offer stability comparable to conventional extended designs. However, localized instability in multisegmental cases suggests a need for careful biomechanical management regardless of the fixation method used.