The Influence About Premolar Extraction Of The Effects On Upper Airway Morphology And Hyoid Position In Angle Class Ⅰ With Premature Permanent Occlusion

Objective This research was designed to observe the effects of premolar extraction or non-premolar extraction treatments on upper airway morphology and hyoid position in the Angle Class Ⅰ with premature permanent occlusion by cephalometrics comparing the pretreatment and postreatment upper airway morphology and hyoid position.Discussing Angle ClassⅠ with premature permanent occlusion and tooth extraction or not on the correlation between airway morphology and hyoid position,In order to offer a more reliable theoretical basis for making the clinical orthodontic treatment plan.Methods Choosing from 2015 to 2018 the sufferings of Ningxia People’s Hospital of orthodontics division of early selection of orthodontic patients 60 Angle Class Ⅰ with premature permanent occlusion abnormalities,collect and analyze all good course record for the treatment of patients.According to the orthodontic program design,the patients were divided into two groups: the first group included 30 patients(13 males and 17 females)whose orthodontic program design did not premolar extraction treatment;The second group of30 patients with four first premolar extraction treatment(14 males and 16 females),all the participants aged from 10 to 13 years old(average age 11.2?±?0.7 years old).To measure the shape of upper airway morphology and the position of hyoid bone were by cephalometrics before and after treatment orthodontic and measurement,compareAngle Class Ⅰ with premature permanent occlusion or not before and after orthodontic treatment of upper airway morphology and hyoid position.Result1.The measurement items of upper airway morphology in non-extraction group were compared before and after treatment:The increase of PNS-UPW in palatopharyngeal segment and the decrease of U-MPW in oropharyngeal segment showed significant difference before and after treatment(p<0.05),while there was no significant difference in upper airway morphology before and after treatment in other non-extraction groups(p> 0.05).2.The hyoid position measurement items in non-extraction group were compared before and after treatment:The increase of H-FH and the decrease of H-VL in the sagittal direction showed significant difference before and after treatment(p<0.05),while there was no significant difference in the other indicators of hyoid position before and after treatment in the non-extraction group(p>0.05).3.The measurement items of upper airway morphology in extraction group were compared before and after treatment:the index PNS-UPW of the palatopharyngeal segment increased,the index U-MPW of the palatopharyngeal segment decreased after SPP-SPPW treatment,and the index U-MPW of the oropharyngeal segment decreased.There was significant difference before and after treatment(p<0.05).There was no significant difference in the index of upper airway morphology between the other groups before and after treatment(p> 0.05).4.The hyoid position measurement items in extraction group were compared before and after treatment:indicators reflecting hyoid vertical orientation only H-MP increased after treatment,with statistical significance(p< 0.05);the other indicators reflecting hyoid position in the extraction group had no significant difference before and after treatment(p> 0.05).5.The upper airway morphology measurement items before and after treatment in the non-extraction group and the extraction group were compared before treatment:there was significant difference in TB-TPPW between the two groups(p< 0.05),while there was no significant difference in other indexes of nasopharyngeal,palatopharyngeal andlaryngopharyngeal segments(p > 0.05).The difference of PNS-UPW was significant only in the palatopharyngeal segment(p < 0.05),but there was no significant difference in the other indexes in the nasopharyngeal,palatopharyngeal and laryngopharyngeal segments(p > 0.05).6.The hyoid position was measured before and after treatment in the non-extraction group and the extraction group:there was no significant difference in the hyoid vertical and sagittal indexes between the two groups before and after treatment(p > 0.05).Conclusion1.For the early permanent occlusion with Angle class I malocclusion,the orthodontic treatment of the first premolar with the reduction of four teeth will not change the sagittal diameter of upper airway in a short time,but will affect it.2.The orthodontic treatment of the first premolar with the reduction of four teeth had no significant effect on hyoid position of early permanent occlusion with Angle class I malocclusion.