The effects of orthognathic surgery on pharyngeal airway and quality of sleep

The Effects of Orthognathic Surgery on Pharyngeal Airway and Quality of Sleep Aim: The aim of this study was to determine changes in respiratory function during sleep and pharyngeal airway dimensions following bimaxillary orthognathic surgery. Material and Method: The subjects were 28 patients (17 female and 11 male) in whom Class III skeletal relationship was corrected by Le Fort I advancement and bilateral sagittal split ramus setback surgeries simultaneously. Pharyngeal volume, minimum axial area, linear measurements and position of the hyoid were studied using cone beam computed tomography (CBCT) immediately before surgery (T1) and during a period of 6-12 months postoperatively (T2). All the CBCT scans were assessed and analyzed using Dolphin 11.8 software. Apnoea–hypopnoea index (AHI) and other respiratory parameters were measured with a full polysomnography system. Correlations between the parameters were also analysed. Results: Differences of surgical skeletal, pharyngeal dimensional and polisomographic changes between T1 and T2, did not show significant difference between gender groups (p>0,05). But in within-group level, retrolingual volume decreased significantly in women and whole sample and nazofaringeal volume increased significantly in men and whole sample. Retropalatal volume decreased significanly in only men. Orofaringeal volume decreased significantly in all of the groups and total faringeal volume decreased significantly in only whole sample group (p<0,05). All the minimum axial area parameters restricted significantly in all of the groups (p<0,05). Hyoid bone positioned infero-posteriorly significantly in women and whole sample groups (p<0,05). Antero-posterior linear measurements (AP) of PNS level increased significantly in all of the groups, and the rest of the AP measurements decreased significantly in women and whole sample groups (p<0,05). Lateral linear measurements (LAT) of PNS level increased significantly in men and whole sample groups, LAT of base of tongue level decreased significantly in women and whole sample groups, and LAT of uvula tip level decreased only in whole sample group (p<0,05). Oxygen desaturation index (ODI) of 3% is incresed significantyl only in men group, and ODI of 4% is increased significantly only in whole sample group (p<0,05). Skeletal changes correlated well with pharyngeal airway changes but airway changes did not correlate with polysomographic parameters. Conclusion: Bimaxillary surgery significantly affected pharyngeal airway dimensions but did not cause increase of AHİ which is a critical determinant parameter for obstructive sleep apnea syndrome. Only the ODI of 3% in males and %4 of total samples groups were affected by decreased airway dimensions. Gender differences should be considered when considering changes in pharyngeal airway.