Changes of pharyngeal airway structure and function in patients with skeletal class III malocclusion one year after orthognathic surgery.

Purpose: This study aimed to analyze changes in the pharyngeal airway structure and function in patients with skeletal Class III malocclusion one year after orthognathic surgery.

Materials/methods: In this research, cone-beam computed tomography (CBCT) images of 30 patients (14 men and 16 women; mean age 20-30 years) with skeletal Class III malocclusion who underwent Lefort I osteotomy and bilateral sagittal split osteotomy were obtained before and one year after the surgery. Changes in pharyngeal airway structure were achieved by comparing CBCT data, and changes in function were achieved by comparing fluid dynamics models. The pharyngeal airway was analyzed by Element 3D (E3D) and the nasal airway 3D model was reconstructed. The meshing was implemented in ICEM-CFD (ANSYS, Canonsburg, PA, USA), and improved the mesh quality. The meshes were imported into Fluent (ANSYS, Canonsburg, PA, USA) to stimulate a fluid analysis.

Results: The minimal anteroposterior diameter, minimal cross-sectional area and volume of pharyngeal airway were significantly reduced after surgery. There was no significant difference in the nasopharyngeal cross-sectional area. Pharyngeal airway resistance increased significantly after surgery, wall shear stress changed little before and after surgery. The anatomic structure of pharyngeal airway changed after surgery, but the morphological change of pharyngeal airway was not significant.

Conclusions: One year after surgery, the anatomical structure and function changed compared with those before surgery, and the changes of minimal cross-sectional area of pharyngeal airway should be considered when designing the treatment plan for the patients.