Long-term upper airway changes following mandibular advancement with or without maxillary setback in skeletal class...

This study assessed 2-year oropharyngeal airway changes in skeletal Class II patients following isolated mandibular advancement by bilateral sagittal split osteotomy (BSSO) with or without maxillary setback by Le Fort I osteotomy (Le fort I).

Cone-beam computed tomography (CBCT) data from 25 isolated BSSO and 57 BSSO + Le fort I patients were retrospectively analyzed at three stages: preoperatively (T0), 3 months (T1), and 2 years postoperatively (T2). The total upper airway volume (V), minimum cross-sectional area (CSA_min), and volumes of the nasopharynx (V_NA), velopharynx (V_VE), and glossopharynx (V_GL) were measured via Dolphin Imaging.

Isolated BSSO significantly increased V, CSA_min, V_NA, V_VE, and V_GL by 38.86%, 69.49%, 22.31%, 46.05%, and 46.94%, respectively, at T1 (P < 0.01) and 21.85%, 43.11%, 13.85%, 19.73%, and 25.38%, respectively, at T2 (P < 0.05). From T1 to T2, V, CSA_min, V_VE, and V_GL decreased by 12.24%, 15.56%, 18.02%, and 14.67%, respectively (P < 0.05). Multivariate regression revealed that each 1 mm advancement of the PNS and B points increased V by 1038 mm³ and V_VE by 519 mm³; PNS advancement increased V_NA by 708 mm³ (P < 0.05). Compared with BSSO + Le fort I, isolated BSSO yielded greater short-term improvements (V: +11175 vs. +3638 mm³; P < 0.001) and superior long-term stability in V and V_NA (P < 0.05). Notably, the combined advancement of PNS and B point may be a robust predictor for postoperative changes of the upper airway volume.

Isolated BSSO induces sustained upper airway expansion for 2 years, which is driven primarily by hard tissue advancements. Compared with BSSO + Le fort I, this technique has superior short- and long-term efficacy, providing guidance for the optimized management of skeletal Class II patients.

This study was approved by the Ethics Committee of Peking University Stomatological Hospital (Approval No. PKUSSIRB-202167121).