Analysis Of Upper Airway For Skeletal Class ? And ? Patients On Cone Beam Computerd Tomography In Adolescence

Research background:The upper airway,as a gas inlet channel,is also an important physiological structure of the human skull and maxillofacial region.The upper airway is closely related to the respiratory,vocal and craniofacial growth and development.Rhinitis,gland adenoid,tonsil hypertrophy can lead to upper airway narrowing and obstruction can cause respiratory compensatory changes;these compensatory changes if it lasts for a long time,but also lead to growth and development period in patients with craniofacial structure produces the deformation of different degrees.The main content of examination and measurement of upper airway should be used as orthodontic diagnosis,especially for patients with the growth and development period,accompanied by airway abnormalities in patients with early diagnosis and treatment can be greatly reduced airway in maxillofacial region,normal growth and development of the adverse effects and improve the efficiency of orthodontic treatment.In recent years,more and more attention has been paid to the influence of the upper airway for maxillofacial growth by scholars.Many studies show that the effect of the upper airway may be affected by the skeletal patterns.Scholars through the measurement of different sagittal skeletal patterns in patients with airway size,class ?,class ?,class ? patients becomes smaller,but,some studies suggest that there is no difference between the class I,class II and class III patients.In the past,the study of the upper airway morphology was mainly used to get the two-dimensional information through the lateral X-ray of the skull,which has some limitations in the overall response of the complex three-dimensional structure of the airway.Cone beam Computed Tomography(CBCT)is a relatively new imaging technique,has low radiation,high imaging precision,simple operation,3D reconstruction and measurement of upper airway and become another method in the study of upper airway structure and morphology.Objective:The study was designed to compare the difference of naso/velo-pharyngeal and glossopharyngeal airway of teenagers of skeletal class I with those skeletal class ?,so as to investigate the correlations between the morphology of naso/oro-pharyngeal airway and the maxillofacial structures.Methods:This study selected 80 teenagers(age:10-15,skeletal class I and class II)in first hosptital affiliated to Zhejiang University.The three-dimensional Cone Bean Computed Tomography(CBCT)images of each patients were taken in our hospital under the same condition..All of them were devided into two groups based on their ANB angles.Using the dolphin software for reconstructing the CBCT image of each patient,adusting the middle saggital plane and axial plane in coronal,saggital and axis view,then measuring the distances,volumes and min cross-sectional areas.Results:The volume of nasopharynx,velopharynx and glossopharyx of class ? sagittal facial type group is respectively 5168.352±1695.9989 mm3,8321.45±2823.3025mm3 and 7060.58±2755.3704 mm3.Volumes of class ? are respectively 4827.23±1472.7262mm3,6563.213±1812.642mm3 and 6060.367±2179.8284mm3.Depths of naso/velo/glosso-pharynx of class I are,respectively 14.605±3.4052mm,25.708±4.2976 mm,24.32±5.873mm.Depths of class II are respectively 14.442±34388 mmL,25.082±3.8064mm,24.42±5.409 mm.As to the min-cross sectional areas of airways between the two groups:the cross section area(Class ?:226.163±81.7684mm2?Class? 181.58±56.9521mm2)?segittal diameter(Class I:10.708±3.3997mm?Class II 8.918±2.5793mm)?transverse diameter(Class ?:25.41±5.6086mm?Class ?:23.21±4.0738mm).The difference of volopharyngeal volume?total volume?the min-cross sectional areas?transverse diameter and segittal diameter are significant.Conclusions:Class ? skeletal group of velopharynx volume and total volume compared with skeletal class ? group of upper airway volume significantly reduced.Class ? skeletal pattern group at the min-cross sectional area compared with type ? skeletal group at the min-cross sectional area significantly reduced,reflected in the sagittal diameter and transverse diameter diminish.