3D volumetric analysis of upper airway changes following orthognathic surgery

Orthognathic surgery is frequently performed to correct dentofacial deformities and is known to alter the upper airway morphology. This study aimed to analyze volumetric changes in the upper airway following mono- and bimaxillary surgery using virtual surgical planning, with a specific focus on the minimal cross-sectional area (mCSA) and total upper airway volume (TUAV).

In this retrospective study, 81 patients with Angle Class II or III malocclusions underwent either mandibular advancement (MA), maxillomandibular advancement (MMA), mandibular setback, or a combination of mandibular setback with maxillary advancement. Surgical planning was performed using IPS CaseDesigner® software. Pre- and postoperative CBCT scans were analyzed to assess changes in mCSA and TUAV. Displacement distances were measured for both jaws, and statistical analysis was performed using paired t-tests and Pearson correlation.

MA and MMA in Class II patients resulted in significant increases in mCSA (p = 0.0048 and p = 0.0005, respectively) and TUAV (p = 0.0346 and p = 0.01, respectively). In contrast, mandibular setback in Class III patients showed non-significant decreases in airway parameters, while bimaxillary surgery produced slight, non-significant increases. A mandibular setback of less than 4.05 mm was not associated with a relevant reduction in airway volume.

MA and MMA significantly increase upper airway dimensions and are effective treatment strategies for oropharyngeal airway deficiencies in Class II patients. Minor mandibular setbacks (< 4.05 mm), especially when combined with maxillary advancement, appear to preserve airway volume in Class III patients. These findings highlight the importance of individualized virtual planning to optimize both functional and aesthetic outcomes, while recognizing the limitations of using static CBCT imaging to assess dynamic airway function.