Severe skeletal Class III malocclusion often requires orthognathic surgery to achieve both functional stability and improved quality of life. This study aims to quantitatively evaluate the long-term (>3 years) three-dimensional skeletal stability and patient-reported quality of life (OQLQ) outcomes of a surgery-first approach (SFA) combining anterior segmental osteotomy with bilateral sagittal split osteotomy (SFA-ASO-BSSO) compared to conventional monobloc SFA-BSSO in patients with severe skeletal Class III malocclusion. This retrospective cohort study included 47 adult patients treated with SFA, divided into SFA‑ASO‑BSSO (n=22) and SFA‑Monobloc (n=25). Skeletal displacement and stability were assessed using CBCT scans at four time points (T0–T3), and functional/psychosocial outcomes were evaluated with the 22‑item OQLQ at T0, T2, and T3. Postoperatively, spatial displacements of mandibular basal landmarks (B-point, Pogonion, Menton) demonstrated equivalent setbacks in both groups (p > 0.05), but the SFA‑ASO‑BSSO group achieved significantly greater incisor retraction (‑11.64 ± 2.85 mm vs ‑8.12 ± 2.25 mm, p < 0.001), reduced surgical compensation (ΔL1‑MP: ‑11.85 ± 2.55° vs ‑1.50 ± 1.15°, p < 0.001), and lower need for genioplasty (18.18% vs 56.00%, p = 0.007). Long‑term evaluation confirmed strong skeletal stability in both groups (p > 0.05), with the SFA‑ASO‑BSSO group showing superior esthetic improvement and OQLQ scores at final evaluation (p ≤ 0.001). Integrating an anterior segmental osteotomy into a surgery-first mandibular setback does not compromise long-term skeletal stability. Furthermore, it yields superior immediate surgical decompensation, aesthetic soft-tissue adaptation, and patient-reported outcomes compared to the conventional monobloc technique in severe Class III cases.
