Volumetric Three-Dimensional Evaluation of the Pharyngeal Airway After Orthognathic Surgery in Patients with Skeletal Class III Malocclusion

Background: Orthognathic surgery significantly alters the dimensions of the pharyngeal airway. This study's objective was to assess alterations in the pharyngeal airway volume via cone-beam computed tomography (CBCT) after orthognathic surgery in patients with skeletal Class III malocclusion. Methods: This retrospective study analyzed CBCT images from 23 patients with skeletal Class III malocclusion (13 females, 10 males), who were categorized into two groups based on the surgical approach: double-jaw and single-jaw surgery. The double-jaw group included 13 patients who underwent bilateral sagittal split osteotomy (BSSO) and Le Fort I osteotomy, whereas the single-jaw group included of 10 patients who had underwent BSSO only. CBCT images were evaluated both before surgery and at a minimum of three months after surgery. The oropharyngeal volume (OP), nasopharyngeal volume (NP), total airway volume, posterior airway space (PAS), and the most constricted area at the base of the tongue (minAx) were measured. Statistical analyses were performed using either paired t-tests or Wilcoxon signed-rank tests depending on data normality, with a significance level set at p < 0.01. Results: In the double-jaw group, a significant volumetric increase was observed in the nasopharynx (5316 +/- 1948 mm(3) to 6064 +/- 1899 mm(3); p = 0.010) and oropharyngeal volume decreased from 17,097 +/- 5675 mm(3) to 14,290 +/- 5835 mm(3); however, this reduction was not statistically significant (p = 0.017). In contrast, the single-jaw group showed a significant reduction in oropharyngeal volume from 15,620 +/- 5040 mm(3) to 12,444 +/- 4701 mm(3) (p = 0.010), with no significant change in nasopharyngeal volume (p = 0.551). Total airway volume significantly decreased only in the single-jaw group (from 20,452 +/- 7754 mm(3) to 16,846 +/- 6529 mm(3), p = 0.010). Additionally, both groups exhibited marked decreases in PAS and minimum axial area values (all p < 0.01). Conclusions: Orthognathic surgery led to a significant volumetric increase in the nasopharynx in the double-jaw group, whereas the oropharynx volume significantly decreased only in the single-jaw group. Additionally, both surgical approaches resulted in a marked reduction in PAS and minimum axial area values, highlighting a notable impact on posterior airway dimensions.