Study On Changes In Upper Airway And Surrounding Tissues After Surgery-First Approach Of Patients With Skeletal Class Ⅲ Malocclusion

Objective: To evaluate changes of the upper airway and the surrounding tissues before and after Surgery-First Approach(SFA)in patients with skeletal class Ⅲ,through the comparison with traditional Ortho-First Approach(OFA)Method: 30 patients with skeletal class Ⅲ underwent orthodontic-orthognathic treatment were selected from recent five years in the Affiliated Hospital of Qingdao University.15 patients treated with SFA and 15 patients treated with OFA.The operation was Lefort I and BSSRO without genioplasty.Lateral cephalometric radiographs were taken for each patient one month before surgery(T0),one month after surgery(T1)and after treatment(T2).The FH plane,MP plane,and SV plane were used as the reference plane for cephalometric measurement.The following items were measured: airway items:Nph,Oph,Hph;hyoid bone items: SV-Hy,FH-Hy,Mn-Hy and the vertical distance from Pog to SV plane.The changes of these measurement items in the T0-T2 period of the SFA group and the OFA group were measured respectively,and the changes of the upper airway and surrounding tissues before and after treatment were analyzed by paired t-test.The changes of these measurement items in the T2-T1 period of the SFA group and the OFA group were measured respectively.The changes of the upper airway and surrounding tissues after the operation were analyzed by paired t-test.Independent sample T test was used to compare the difference of upper airway changes between the SFA group and the OFA group during the T0-T2 period and the T2-T1 period.Results:1.SFA group:During the T0-T2 period,the airway items: Oph reduced by 1.52 mm(P<0.05),indicating that the oropharyngeal airway space significantly reduced after treatment,and the change was statistically significant.Nph reduced by 0.32 mm and Hph reduced by0.88 mm(P>0.05),indicating that the changes in the nasopharyngeal and laryngopharyngeal airways were small after treatment,and there was no statistical significance.The hyoid bone items: SV-Pog reduced by 3.36mm(P<0.05),indicating that the mandibular level in horizontal direction significantly after treatment,and it’s statistically significant.For the remaining measurement values,there were no obvious difference(P> 0.05).During the T2-T1 period,the airway items: Oph increased by 1.12 mm,Hph increased by 1.76 mm,Nph increased by 1.48 mm(P<0.05),indicating that the he upper airway space showed certain recovery,and the change was statistically significant.The hyoid bone items: SV-Hy increased by 2.76 mm,FH-Hy increased by 4.60 mm,SV-Pog increased by 3.36 mm,(P<0.05),indicating that the hyoid position recovered in the horizontal and vertical directions was significant statistically..2.OFA group:During the T0-T2 period,the airway items: Oph reduced by 1.33 mm(P<0.05),indicating that the oropharyngeal airway space significantly reduced after treatment,and the change was statistically significant;Nph reduced by 1.25 mm and Hph reduced by0.91 mm(P>0.05).The changes of airway in the nasopharynx and throat were not statistically significant before and after treatment.The hyoid bone items: SV-pog reduced by 2.00 mm(P<0.05),indicating that the mandibular level in horizontal direction changed significantly.During the T2-T1 period,the airway items: Oph increased by 1.16 mm,Hph increased by 2.00 mm,and Nph increased by 2.75 mm(P<0.05),indicating that the upper airway space was restored after surgery,and the change was statistically significant.The hyoid bone items: SV-pog increased by 1.25mm(P<0.05),indicating that the mandibular changes in the horizontal direction were significant;FH-Hy increased by 4.33 mm,(P<0.05),indicating that the position change of the hyoid bone recovered in the vertical directions was statistically significant.3.Comparison between SFA group and OFA group:During the T0-T2 period,the changes of upper airway were compared between the two groups.Oph value indicated that the oropharyngeal airway space recovered slowly in the SFA group compared with the OFA group(P<0.05).The difference in the remaining measurement items was not statistically significant(P> 0.05).During the T2-T1 period,the changes in upper airway were compared between the two groups.Nph,Oph,Hph,SV-Hy,FH-Hy,Mn-Hy,and SV-Pog showed no significant difference in postoperative recovery of the upper airway and hyoid bone between the two groups(P >0.05).Conclusion: SFA could reduce the upper airway space and change the position of the hyoid bone of patients with skeletal class Ⅲ.Compared with OFA treatment,the oropharyngeal airway space recovered slower after SFA treatment.After the treatment,except for the oropharyngeal airway space,the remaining measurement items basically restored to the pre-treatment levels.