Effects of bimaxillary orthognathic surgery on pharyngeal airway and respiratory function at sleep in patients with class III skeletal relationship.

PURPOSE: The aim of this study was to examine the effects of bimaxillary orthognathic surgery on pharyngeal airway space (PAS) and respiratory function during sleep.

MATERIALS AND METHODS: The subjects were 21 patients with class III skeletal relationship, and all of the patients underwent bimaxillary surgery (Le Fort I advancement and bilateral sagittal split ramus setback osteotomies simultaneously). Pharyngeal volumes of nasopharyngeal (V-NPA), retropalatal (V-RPA), retrolingual (V-RLA), oropharyngeal (V-ORO) and total pharyngeal airways (V-TOT); minimum axial areas of retropalatal (MA-RPA), retrolingual (MA-RLA) and oropharyngeal airways (MA-ORO); and position of the hyoid were studied in order to detect dimensional PAS changes using cone-beam computed tomography (CBCT) with Dolphin 11.8 software immediately before surgery (T1) and during a period of 6-12 months postoperatively (T2) in all of the patients. Apnea-hypopnea index (AHI), respiratory disturbance index (RDI) and apnea in supine position (SupAHI) parameters were measured with a Compumedics E series full polysomnography system.

RESULTS: In volumetric measurements, the V-ORO parameter decreased significantly (p < 0,05) while there was no statistically significant change in the rest of the volumetric parameters (p > 0,05). All of the minimum axial area parameters were decreased significantly (p < 0,01). Hyoid bone moved inferiorly (p < 0,05) and posteriorly (p < 0,05). None of the polysomnographic parameters changed significantly (p > 0,05).

CONCLUSION: Bimaxillary orthognathic surgery significantly narrowed PAS dimensions but did not cause an increase in AHI, which is a critical determinant parameter for obstructive sleep apnea syndrome.