CBCT Study Of Upper Airway Morphology And Hyoid Position In Skeletal Class ? And Class ? Children

Objective:There is an interaction between the craniofacial structure and the upper airway.Craniofacial abnormalities will cause abnormal development of the upper airway,as well as the change of hyoid position.The paper takes the three-dimensional individual reconstruction of CBCT data as the basis to analyze the actual upper airway morphology and the position of hyoid bone in children patients of skeletal class III and class I,to provide important theoretical basis for the establishment of orthodontic treatment plan and evaluation of treatment effect in children patients with skeletal class III.Materials and Methods:20 patients who were diagnosed as skeletal class III in orthodontic Department of Stomatology Hospital of Shandong province from July 2012 to July 2016 were randomly selected as research group.The age range of research group was 8-12 years old,and the average age was(10.2 ± 1.3)years old.20 patients with skeletal class I were selected as control group.The age range of control group was 8-13 years old,and the average age was(10.8 ±1.5)years old.The two groups of patients were paired according to actual age and sex.All subjects were treated with CBCT by the Radiology Department before treatment.3D reconstruction of the upper airway and hyoid bone were performed with MIMICS 17.0.T-test was used to compare the upper airway morphology and hyoid position between two groups.The relationship between hyoid position and pharyngeal morphological variables(cross-sectional area,cross-sectional shape and volume)correlation coefficient.Results:Compared with bone patients,the cross-sectional area and other parameters of patients with orthopedic class III increased significantly,while the cross-sectional shape was more elliptical.The most significant difference in cross-sectional shape,cross-sectional area,and volume is the glossopharynx.The height of each pharyngeal segment,the nasopharyngeal related indexes,and the anteroposterior diameter of velopharynx and glossopharynx showed no statistic differences between two groups.The horizontal and vertical direction of hyoid bone were larger in skeletal class III patients than that in skeletal class I patients,indicating that the hyoid bone in skeletal class III patients was in a more anterior and inferior position.The horizontal direction of the hyoid bone was positive correlated with the cross-sectional shape,cross-sectional area and volume of velopharynx and glossopharynx.The vertical direction of the hyoid bone was only positive correlated with the morphological indexes of glossopharynx.No significant correlation was observed between the hyoid bone position and the morphological indexes of velopharynx.Correlation:Children patients with skeletal class III malocclusion had better airway openness than those with skeletal class I,and the hyoid bone position was in a more anterior and inferior position.For the treatment of skeletal class III malocclusion,a certain range of mandibular retrogression was allowed.However,in order to achieve the purpose of both aesthetic and functional,we should pay attention to the change of hyoid bone position and upper airway morphology when mandibular retrogression in clinical practice.