| Objective: This study aimed to investigate and compare morphologic changes after mandibular setback sagittal split ramus osteotomy(SSRO)on the position of hyoid bone and pharyngeal airway space(PAS)in men and women,in order to assess the risk of obstructive sleep apnea syndrome(OSAS)and provide a reference for clinical orthognathic treatment.Methods:According to the inclusive criteria,60 patients(30 female,30 male)who had undergone bilateral mandibular setback sagittal split ramus osteotomywere selected as case group.Lateral cephalograms were taken preoperatively,postoperatively within 1-2weeks,and follow-up after 6-12 months.The control group included 60 adult patients(30female,30 male)with normal sagittal facial type,whose lateral cephalograms were taken before orthodontic treatment as measurement data.The measurements are listed as follows: the vertical position of hyoid bone(H-X,H-MP);the horizontal position of hyoid bone(H-C3,H-Ge);the PAS sagittal distance(PNS-UPW,U-MPW,MT-MTP,EPA-EPP);the PAS sagittal area(NSP,UOP,LOP,LGP)were measured with Auto CAD 2014 on the lateral cephalograms.Evaluated and compared the position of hyoid bone and pharyngeal airway space between genders.The data were statistically analyzed by SPSS 19.0.Results:1.H-X and H-C3 of men were significantly greater than that of women in each group(P<0.05).H-MP revealed statistically significant difference between genders in the case group at 1-2weeks postoperatively and in the control group(P<0.05).The above results indicate the male had a forward and inferior position of the hyoid bone than that of the female.2.The PAS measurements(U-MPW,MT-MTP,EPA-EPP,UOP,LOP,LGP)of men were significantly greater than that of women preoperatively and at 6-12 months after surgery(P<0.05).The PAS measurements(MT-MTP,EPA-EPP,UOP)of men were greater than that of women at 1-2weeks after surgery(P<0.05),as well as MT-MTP and EPA-EPP of the control group(P<0.05).These results show that the PAS of the male is larger than that of the female in patients with class III sagittal facial type and the normal ones.3.Compared with the control group,H-X and H-MP of the case group preoperatively were smaller while H-C3 was larger for both genders(P<0.05).The PAS measurements(U-MPW,MT-MTP,EPA-EPP,UOP,LOP)preoperatively were significantly larger than that of the control group(P<0.05),These results show that the patients with class III sagittal facial type had a forward and superior position of the hyoid bone and a larger PAS than the normal ones.4.Compared with preoperative values,H-X、H-MP significantly increased and H-C3、the PAS measurements(U-MPW、MT-MTP、EPA-EPP 、 UOP 、 LOP 、 LGP)significantly decreased at 1-2 weeks after surgery.Compared with the values of 1-2 weeks after sugery,H-X significantly decreased while H-C3 and the PAS measurements(U-MPW、MT-MTP)significantly increased at 6-12 months after surgery.There was no statistically significant change in the hyoid bone position and the PAS between the case group at 6-12 months after surgery and the control group(P>0.05),indicating that the hyoid bone moved backward and inferior immediately after surgery,the PAS decreased at the same time,while a period of time later,the hyoid bone showed a tendency to move forward and upward,the PAS increased gradually and basically close to the normal range.Conclusions:1.The male had a forward and inferior position of the hyoid bone and a larger PAS than that of the femalein thepatients with skeletal mandibular prognathism.2.The patients with skeletal mandibular prognathism had a forward and superior position of the hyoid bone and a larger PAS than the normal ones.3.The hyoid bone of patients with skeletal mandibular prognathism of different genders moved backward and inferior immediately after surgery,and the PAS decreased,while the hyoid bone had a tendency to move forward and upward,and the PAS returned to normal 6-12 months postoperatively,indicated there is no increased risk of OSAS and no difference in genders after surgery. |
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