Changes Of Oropharyngeal Airway After Orthodontic Extraction Treatment In Adolescents

Objective:To evaluate the changes of oropharyngeal airway after orthodontic extraction treatment and explore the effect of extraction on upper airway,and to provide references for orthodontic treatment in adolescents.Contents:1.Changes of oropharyngeal airway after orthodontic extraction treatment in adolescents: A Meta-analysis.2.Three-dimensional changes of oropharyngeal airway after orthodontic extraction treatment in skeletal class Ⅰ adolescents.Methods:1.Quantitative system review: all literatures about volumetric and minimum cross-sectional area changes in oropharyngeal airway after orthodontic extraction treatment in adolescents were retrieved from the database: Pub Med,Embase,Web of Science,Cochrane library,CBM,CNKI,VIP and Wan Fang.The search ended in February2019.Included studies were evaluated using the methodological index for non-randomized studies(MINORS)and were analyzed by Rev Man 5.3.2.Retrospective cohort study: 30 adolescent patients CBCT data before and after orthodontic extraction treatments were studied retrospectively.Dolphin 11.8 software was used to segment the upper airway,and the relevant indexes of oropharyngeal airway volume and cross-sectional area were measured,then cephalograms was generated to measure teeth-jaw indexes and hyoid positions.T test and correlation analysis were used to analyze the data by SPSS 26.0.Results:1.Finally,5 articles were obtained,including 6 groups of studies and 124 subjects.The results of meta-analysis showed that the change of palatopharyngeal volume after tooth extraction was +1.21 cm~3(p=0.02),the change of glossapharyngeal volume was+2.05 cm~3(p=0.0006),the change of oropharyngeal volume was +2.03 cm~3(p=0.008),and the change of oropharyngeal minimum cross-sectional area was +36.31mm(p=0.0008).The changes of the four indexes were statistically significant(P<0.05).2.After extraction treatment,palatopharyngeal volume,glossopharyngeal volume,oropharyngeal total volume and minimum cross-sectional area increased,and the difference was highly statistically significant(P<0.01);Meanwhile,minimum cross-sectional area of oropharynx is mostly located in the glossopharynx;The cross-sectional area at the uvula apex,its maximum antero-posterior diameter,and the ratio of the maximum antero-posterior diameter to the maximum lateral diameter all decreased,and the difference was statistically significant(P<0.05),indicating that its shape tended to become more elliptical after treatment.In addition,the decrease of the cross-sectional area at the uvula apex was correlated with the decrease of the lip inclination of the mandibular central incisors and the retraction of the maxillary and mandibular central incisors(P<0.05).Conclusions:1.Systematic review based on available clinical evidence: According to the existing clinical evidence,the total volume of palatopharynx,glossopharynx,oropharynx and the minimum cross-sectional area of oropharynx all increased after orthodontic extraction treatment by non-maximum anchorage.2.By the non-maximum anchorage,the impact of orthodontic extraction treatment on oropharyngeal airway is generally small in skeletal class Ⅰ adolescents,but it can change the shape of the airway to some extent which was correlated with the retraction of anterior teeth.3.In order to increase airway ventilation or prevent iatrogenic OSAHS,orthodontists need to make a comprehensive and systematic assessment of the morphology and function of the upper airway.4.The orthodontic treatment time is long and there are many confounding factors.Although this conclusion can provide certain reference for designing orthodontic programs,it still needs to be verified by prospective studies with higher quality and larger samples in the future.