Surgery-first segmental orthognathic surgery for treatment of hemimandibular elongation: a novel modified modality.

BACKGROUND: The application of a surgery-first approach in patients with hemimandibular elongation (HE) remains poorly defined. In this pilot study, we introduce a modified surgery-first segmental orthognathic surgery (OGS) technique that integrates novel osteotomy design and structural precision to address HE.

METHODS: Nine patients with HE underwent segmental Le Fort I osteotomy, bilateral sagittal split ramus osteotomy (BSSRO), and unilateral mandibular body osteotomy, using both virtual surgical planning (VSP) and individualized cutting guides. Surgical accuracy was evaluated by comparing three-dimensional (3D) models obtained at 1 week postoperatively (T1) with VSP. Mid-term skeletal stability was assessed by comparing 3D models at T1 with those at 6-12 months postoperatively (T2). Symmetry-related parameters (chin deviation, chin rotation, bilateral mandibular body length discrepancy, and asymmetry index) were measured and compared.

RESULTS: All patients healed uneventfully without major complications. Surgical accuracy analysis showed a mean 3D deviation of 1.58 ± 0.39 mm between VSP and T1. Significant improvements were observed in all symmetry parameters at T1 (p < 0.05). At mid-term follow-up (mean 8.2 months, range 6-12 months), chin deviation, chin rotation, bilateral mandibular body length discrepancy, and asymmetry index showed no significant changes from T1 to T2.

CONCLUSIONS: This pilot study demonstrates that the modified surgery-first segmental OGS technique achieves good surgical accuracy, immediate improvement in facial symmetry, and acceptable mid-term skeletal stability. This approach, integrating a unique osteotomy design, VSP, and 3D-printed cutting guides, offers a promising preliminary solution for complex facial asymmetry.