Effect On Upper Airway And Its Surrounding Tissues Of Class ? Malocclusion Patients After Extraction Treatment

Objective:This thesis is to analyze whether the upper airway and its surrounding tissues of class ?average-angle malocclusion patients are effected after extraction treatment of the four first premolars,and if effected,the correlations between the variation of craniofacial and dental items and the change of upper airway and its surrounding tissues by observing the change of indexes of craniofacial,upper airway dimensions and hyoid location before and after the extraction treatment.Methods:This thesis chosed 40 class I(ANB 0.7?4.7)facial type patients with MP-FH between 21.2°?33.4°and a congestion degree below 11° as well as NSL-CVT<5°.The patients were equally divided into two groups.Members of group I were conducted first premolar extraction treatment with front teeth pulled back by medium strength.8 upper airway indexes,4 hyoid location indexes and 2 tongue indexes were collected to conduct statistical analysis by applying comparative t-test,independent t-test and Pearson correlation test.Results:1.The variation of indexes of the two groups before and after the extraction treatmentAs for group I,the indexes of ?SNA??SNB??U1-SN??L1-MP?U1-AP?L1-AP?U1-Y?L1-Y decreased and of statistical significance.Other indexes have no significant variation.As for group ?,the increase of L1-MP indexes was the only to have statistical significance.The indexes of upper airway of both groups were of no significant variation,nor was the hyoid location indexes.As for group I,average H-NP and H-FH increased to show a trend of posteroinferior movement after extraction.The length and width of tongue before and after extraction treatment were not statistically varied.While TGH value statistically increased in group ?.2.The correlation analysis of the variation of craniofacial and dental items and the change of upper airway and its surrounding tissues in group ?The SPAS of nasopharynx has the highest correlation with U1-Y and L1-Y,but of no obvious variation.The MAS of pharynx oralis has a positive correlation with L1-AP and L1-Y.CoGn,L1-Y and H-FH posed a positive effect on the V-LPW of laryngo-pharynx airway dimensionConclusions1.There would not be constrictive effect of upper airway dimensions after conducting extraction treatment of four first premolars with front teeth pulled back by medium strength to class ? average-angle malocclusion patients.2.There would be a limited tongue movement of posteroinferior dimension after extraction treatment.3.The extraction treatment would impose certain effect on the volume of inherent tongue tissue.