Comparison of the Change in Pharyngeal Airway Space, Tongue and Hyoid Bone Positions According to the Orthognathic Surgical Methods of Mandibular Prognathism
Materials and Methods : The subjects included 30 patients(16 male, 14 female) with skeletal Class III malocclusion. Group 1(10 patients) underwent BSSRO only, Group 2(10 patients) underwent BSSRO with genioplasty, Group 3(10 patients) underwent BSSRO, Lefort I osteotomy. we measured the lines between selected upper air way, hyoid bone, tongue landmarks on lateral cephalometric x-ray films of skeletal class III 30 persons who had not been operated yet, were within 1 week after operation, were 3-6 months after operation, were 1 year after operation. And we compared them and analyzed them with Matched paired t-test, Independent samples t-test.
Results : There were no postoperative changes nasopharyngeal airway space in Group 3. Also during follow-up period increased than preoperative. In group 1, 2, 3 immediative postoperative oropharyngeal and hypopharyngeal airway space was decresed. During following period the hypopharyngeal airway space returned to the preoperative positions but the oropharyngeal airway space were not significantly changed. The upper and lower tongue was posteriorly repositioned immediately after surgery. During follow-up period, lower tongue posture returned to the preoperative positions, and upper tongue posture were not significantly changed. Immediately after surgery, the B point was moved to posterior position but slightly anterior advancement was found during follow-up period.
Conslusions : Patients who received mandibular setback surgery showed decrease in the PAS, and those who underwent maxillary advancement showed a significant increase of the nasopharyngeal airway space and that remained stable during the evaluation period. Change of airway space, position of the hyoid bone and tongue did not differ according to the presence or absence of the genioplasty.
Reference : 1.Marsan G, Cura N, Emekli U: Changes in pharyngeal (airway) morphology in class III Turkish female patients after mandibular setback surgery. J Craniomaxillofac Surg 36:34, 2008
2. Chen F, Terada K, Hua Y, et al: Effects of bimaxillary surgery and mandibular setback surgery on pharyngeal airway measurements in patients with class III skeletal deformities. Am J Orthod Dentofac Orthop 131:372, 2007