CBCT Analysis of the Hyoid and Pharyngeal Airway Changes in Class III Patients With Orthognathic Surgery

This study was designed to investigate the response of the respiratory structures to orthognathic surgery in patients with Class III malocclusion, with a specific emphasis on the vertical placement of the hyoid bone. The correlations of these changes were also analysed, followed by further subgroup analyses based on preoperative conditions.

Dolphin software was used to obtain cephalometric landmarks, airway and hyoid bone measurements from pre- and postoperative CBCT scans of 31 patients. Statistical analyses included paired t-tests and Pearson's correlation analysis.

Stomatological mandibular values and the nasopharynx height showed significant changes. Pearson's correlation identified significant correlations between changes in B and H horizontal coordinates (p < 0.05), as well as between changes in H longitudinal coordinates and specific airway dynamics (p < 0.05). Patients with a lower preoperative hyoid position experienced a more pronounced decrease in hypopharyngeal airway volume after surgery compared to those with a higher preoperative hyoid position, as evidenced by the significant mean differences and p values (p < 0.01).

Class III patients experienced airway constriction following orthognathic surgery, particularly those with a lower preoperative hyoid bone position, who showed a more significant decrease in hypopharyngeal airway volume postsurgery compared to those with a higher preoperative hyoid position. These findings underscored the importance of individualised surgical planning and highlighted the need for further research with dynamic assessments to optimise respiratory outcomes.