[Changes of upper airway morphology induced by mandibular advancement in patients with obstructive sleep apnea syndrome].

OBJECTIVE

To determine the changes of upper airway morphology induced by mandible position from central relation to advancement position in patients with obstructive sleep apnea syndrome.

METHODS

Nineteen patients (17 males and 2 females) suffering from obstructive sleep apnea syndrome were confirmed with polysomnography. Occlusal wax record was made with mandible in advancement position. Helical computed tomography was performed on each patient in central relation and mandibular advancement position with wax record in situ respectively. On each slice, anteroposterior and transverse diameters were obtained. Airway shape was expressed as the anteroposterior/transverse (AP/T) diameter ratio. Paired-samples t test was employed to compare the measurements.

RESULTS

With mandibular advancement, average and minimal diameters of glossopharynx and hypopharynx were increased significantly. Compared with it, the change of transverse diameter was more prominent. All segments of upper airway were increased significantly except hypopharynx laterally. Moreover, the change of velopharynx shape was observed on axial planes. Ellipse with transversal long axis became more compressed.

CONCLUSION

Upper airway morphology of all segments was influenced by mandibular advancement whether in the sagittal or transverse plane of space, or airway shape. Not only anatomic connection but also regulation of the nerve system and other still unknown mechanism make contribution to the changes of upper airway morphology in patients with obstructive sleep apnea syndrome. The changes of upper airway morphology above mentioned constitute the rationale of treatment of obstructive sleep apnea syndrome with oral appliances.