A Novel Method of Correcting Lower Facial Asymmetry: Computer-Assisted Surgery with Contralateral Mandibular Outer Cortex Sandwich Grafting.

Background: Lower facial asymmetry often results in an esthetically unpleasing appearance. The purpose of this study was to develop a novel method for correcting lower facial asymmetry using mandibular augmentation with sandwich bone grafts from the contralateral mandibular outer cortex (MOC), and to evaluate the efficacy of this method using computer-assisted techniques.

Methods: The medical records of 16 patients with lower facial asymmetry who underwent mandibular augmentation with sandwich bone grafts from the contralateral MOC between January 2016 and December 2019 were retrospectively reviewed. Preoperative computer-aided design (CAD) was performed based on CBCT data, MOC grafts were harvested from the donor side using a 3D printed osteotomy guide template and grafted to the recipient side in sandwich manner to augment the contralateral mandible. Effectiveness was evaluated through pre- and postoperative CBCT data and FACE-Q questionnaire scores. Neurosensory recovery of the inferior alveolar nerve was assessed using the functional sensory recovery (FSR) scale.

Results: All procedure were successfully completed, and the asymmetry was effectively corrected three-dimensionally with no serious complications. The patients' FACE-Q scores for satisfaction with the lower facial area significantly increased from 52.19±7.51 to 86.69±7.50. No significant differences were observed in the pre- and postoperative lengths of mandibular ramus or body on either side. The donor site volume increased by 559.38±335.12 mm at 6 months postoperatively. The recipient site volume increased by 4415.94±1017.21 mm on the 7 day postoperatively and decreased by 202.63±300.85 mm at 6 months, reflecting a bone resorption rate of 5.67 ± 8.12%. The median FSR time for the chin and lower lip was 90 days.

Conclusions: Mandibular augmentation with contralateral MOC sandwich grafts effectively increases mandibular width and volume with a low resorption rate. This method allows for three-dimensional restoration of facial symmetry in cases of mild to moderate lower facial asymmetry, achieving a harmonious and symmetric appearance.

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