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.