Study On The Stability Of Upper Airway After Different Functional Treatments Combined With Fixed Orthodontic

Objective: Applying Herbst and Twin-block combined with fixed orthodontics to treat classⅡmalocclusion separately,to evaluate the stability of the upper airway after function with fixed orthodontic treatment.Methods: 42 adolescents with classⅡmalocclusion were selected,21 patients with Herbst combined with fixed appliances for the study group(Group H)and 21 patients with Twin-block combined with fixed appliances for the control group(Group T).Celphalometric analysis of the dentofacial structure,upper airway sagittal diameter and hyoid bone position were performed before functional treatment(originally diagnosed),after function orthodontics and after fixed orthodontics.The measurement data was analyzed by independent sample t test.Results:1 After functional treatment,SNA angle decreased,SNB angle increased and ANB angle significantly decreased in both Group H and Group T(P<0.01).The angle of the lower incisors in the Group H was increased,and the angle of the upper incisors in the Group T treatment group was reduced,and the difference was statistically significant(P<0.01).Changes between the two groups were statistically significant(P<0.05)except for SNA angle.About sagittal diameter of the upper airway,differences in nasopharynx(PNS-Ba,PNS-UPW)and hypopharynx(V-LPW)had no statistical significance(P>0.05),the velopharynx(SPP-SPPW,U-MPW,Mc1-Mc2 in Group H were increased respectively by 1.84±0.78 mm,1.81±1.67 mm,1.78±0.90mm;in Group T were increased respectively by 1.23±1.20 mm,1.09±0.93 mm,1.66± 1.28mm)and glossopharyngeum(PAS in Group H increased by 3.02±0.73 mm,in the Group T increased by 2.36±0.86mm)significantly increased(P<0.05),glossopharyngeum changes more significantly(P<0.01).Comparison changes between the two groups were significantly significant in velopharynx and glossopharyngeum,especially in glossopharyngeum.Hyoid bone forward within two groups(AH-Or,AH-RGn,AH-NP in Group H were decreased respectively by 2.90±1.12 mm,3.01±1.95 mm,3.09±1.86 mm,in Group T were decreased respectively by 2.69±1.65 mm,2.73±1.30 mm,2.66±1.40 mm,AHCVP in Group H increased by 2.52±1.63 mm,in Group T increased by 2.43±1.17 mm,P<0.01),vertical items were not statistically different except for AH-MP(Group H decreased by 5.19±0.87 mm,Group T decreased by 5.81±0.98 mm,P<0.01).Of all the hyoid items,changes between the two groups had no statistical significance(P>0.05)except for AH-MP(P<0.05).2 After fixed orthodontics,dentofacial structure within two groups were not statistically different(P>0.05).The angle of the lower incisors in the Group H was reduced,and the angle of the upper incisors in the Group T was increased,and the differences were statistically significant(P<0.05),so as changes between the two groups(P<0.01).About upper airway,although the sections were slightly increased,but only the PAS increased by 1.57±1.21 mm in Group H,which was statistically significant(P<0.05).Comparison of glossopharyngeal between groups was increased 0.71±1.31 mm in Group T,Group H>T,the difference was statistically significant(P<0.05).The hori-zontal position of the hyoid bone without significant change(AH-Or,AH-RGn,AH-CVP,AH-NP,P>0.05)and vertical items in addition to the AH-MP(P>0.05),AH-FH,AH-SN,AH-PP,AH-PNS significantly increased,and the changes between the two groups had no statistical significance(P>0.05).Conclusions:1 While treating classⅡmalocclusion,Herbst appliance can increase velo-pharyngeal and glossopharyngeal sagittal diameter,especially the glossoph-aryngeum and the effect is better than Twin-block appliance.2 Herbst and twin-block combined with fixed orthodontics treating classⅡmalocclusion,the changes of upper airway can still keep stable state,especially the glossopharyngeum changes after Herbst combined with fixed orthodontics.