Long-term upper airway changes following mandibular advancement with or without maxillary setback in skeletal class II patients: a 2-year retrospective study.

OBJECTIVE

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).

MATERIALS AND

METHODS

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 (CSAmin), and volumes of the nasopharynx (VNA), velopharynx (VVE), and glossopharynx (VGL) were measured via Dolphin Imaging.

RESULTS

Isolated BSSO significantly increased V, CSAmin, VNA, VVE, and VGL 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, CSAmin, VVE, and VGL 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 VVE by 519 mm³; PNS advancement increased VNA 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 VNA (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.

CONCLUSION

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.

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