SA2 - A 3D CBCT Study of Regional Airway Adaptations After Le Fort I Advancement in Patients With Maxillary Deficiency

Abstract: Orthognathic surgery, particularly Le Fort I advancement, is a key intervention for correcting maxillary hypoplasia and associated dentofacial deformities. This procedure can alter upper airway dimensions with potential implications for breathing and sleep function. Patients with maxillary deficiency often exhibit a constricted posterior airway space, particularly in the oropharynx, which can impair airflow and lead to obstructive sleep apnea. Le Fort I advancement is thought to enlarge this space by repositioning the maxilla anteriorly, resulting in a wider and less collapsed airway. While there have been previous studies demonstrating 3D volumetric changes after orthognathic surgery, none have analyzed if the airway shape changes to become less collapsed after surgery. This study aims to evaluate the impact of Le Fort I advancement on posterior airway space using both 2D and 3D measurements.

Pre- and postoperative cone-beam computed tomography (CBCT) scans were compared in patients undergoing Le Fort I advancement at a single institution between 2020 and 2024. Volume and minimum cross-sectional area (MCA) measurements were assessed separately in the nasopharyngeal, retropalatal, and retroglossal regions. Lateral (L) and anteroposterior (AP) dimensions of the MCA were taken and the ratio (L:AP) was calculated, with a number closer to 1 signifying more shape change from collapsed to circular. Standardized segmentation protocols and reproducible anatomical landmarks were used for all measurements. Descriptive statistics and t-tests were used to analyze data, with a P < .05 was considered significant.

A total of 17 patients were included, of which 8 (47.1%) were male. The average age at which orthognathic surgery was performed was 17.9 years. In the nasopharynx, there were no significant changes in the L:AP ratio or MCA, but the mean airway volume increased significantly postoperatively (5697.2 ± 1262.1 vs 6422.4 ± 2106.3 mm³, P = .04). The MCA (123.5 ± 87.1 vs 196.4 ± 115.1 mm², P = .01) in the retropalatal region increased after surgery and L:AP ratio (2.1 ± 0.7 vs 1.9 ± 0.6, P = .049) decreased, with 11 (64.7%) patients exhibiting increased AP dimensions. No statistically significant changes were observed in the L:AP ratio, MCA, or airway volume in the retroglossal region.

Le Fort I advancement is associated with increased posterior airway volume in the nasopharynx and increased MCA in the retropalatal region, as measured by CBCT. The change in L:AP ratio in the retropalatal region, the area most commonly compromised in patients with sleep apnea, highlights the change from a collapsed to a more patent airway after surgery. While the clinical impact on functional outcomes such as sleep-disordered breathing requires further investigation, these anatomical improvements provide a strong rationale for considering airway effects in orthognathic surgical decision-making.