| Upper airway is an important organ within human body,which is the only muscular channel for air exchange during breathing when air going from outside into lung.Upper airway connects to nasal cavity,oral cavity,and lower esophagus,It has been defined into three parts which are nasopharynx,Oropharynx,and Hypo pharyngeal.Furthermore Oropharynx could be divided into velopharyngeal and glossopharyngeal.Velopharyngeal is the part between the hard palate and the tip of the uvula,and glossopharyngeal is the part between the tip of the uvula and the top of the epiglottis.Due to the anatomic structure of upper airway is very special,while breathing,perhaps caused by some reason,the air could be blocked when it flows through upper airway.Therefore,in order to adapt relevant neuromuscular tissue,this phenomenon will cause a series of changes for craniofacial structure.Finally will lead to related complications[1].For example: cause the position changes of the hyoid bone and mandible.If this issue happens during growing period such as childhood and juvenile era,it will cause hypo-genesis for the relevant organs.On the other hand,the hypo-genesis and abnormity of craniofacial bone’s structure will increase the airway blocking situation.The two factors and phenomenon affect each other,and caused by each other.The development of craniofacial bone includes sagittal and vertical development.So far,the researches about craniofacial bone sagittal abnormal development will lead to the upper airway structural and functional changes have already been concluded.However,different researches give varied conclusion for the impact on airway with same condition of sagittal bone structure but with different condition of vertical bone structure,and there is no final validation yet.For example,it has been well recognized that the classⅡskeletal retrognathia will cause airway stenosis,and leads to blocking air flowing through upper airway,and then trigger the OSAHS.However,with the different conditions of class Ⅱ skeletal vertical bone construction,upper and lower airway structure,form,and function abnormal changes is normally reported within the researches that study with the sample cases of osah.There is rarely research about non-asah population,and there is different perception for the conclusion as well.The construction of upper airway is a three-dimension(3-D)cone-shaped tube,due to varies of limits,most of the researches about the construction are based on two-dimension(2-D)X-ray film,it is not precise to use 2-D film to describe 3-D cone-shaped construction.However,according to many researchers’ studies,it has been proved that the upper airway becoming narrow most happens in the oropharynx section of the airway,due to the abnormal growth of craniofacial bone,and it is not obviously showing the link while nasopharynx and hypo pharyngeal have abnormity.This research does not use the previous researching method,but using the 3-D Cone-Beam CT(CBCT),focusing on the adults who have different classⅡskeletal vertical bone 3-D construction,to re-build the oropharyngeal section and hyoid bone position,in order to reveal the relationship between the upper airway volume abnormal changes with diverse classⅡskeletal vertical bone construction,and also the relationship between the hyoid bone position abnormal changes with class Ⅱ skeletal vertical bone construction.In order to provide the clinical reference for orthodontic clinical diagnosis and reference for researching the pathogenic factors of OSAHS.Objective: By using CBCT to rebuild 3-D construction,to analyze the relativity between different classⅡskeletal vertical bone and the changes of airway volume and hyoid bone position for adult patient,thereby to provide scientific basis for defining treatment plan of orthodontic clinical treatment.Methodology: experiment subjects are with classⅡskeletal(SNA>5°),age between18 to 25 years old,of average age 28.5 adults.Sample selecting from year 2014 to 2016,90 patients with class Ⅱ skeletal who received treatment in Shenyang Stomatology Hospital,and measured by different groups by male and female.Based on patients’ CBCT lateral cephalogram SN.plate as base level,according to male and female patients’ Go Gn-SN angle divide into three groups,which are average angle group(22°<Go Gn-sn<32°),low angle group(Go Gn-SN≤22°),and high angle group(Go Gn-SN≥32°).Before CBCT scanned,adjust patient’s head,to ensure that patient’s Frankfort horizontal plane is in the direction parallel to the ground plane,occlusal position is at the intercuspal position,holding the breath at end of breath,using Ka Vo3 D e Xam machine to scan,and at the mean while all the scans are done by the same person in the radiology department of the hospital.Then,import these illness cases into Ka Vo cone beam 3D imaging e Xam Vision 1.9 system,for all kinds of data measurement and rebuild 3D construction,at the same time to measure the volume of velopharyngeal,all section of glossopharyngeaus,whole upper and lower airway,and the position of hyoid bone,comparing the difference between each group,and then to analyze the relativity between diverse class Ⅱ skeletal vertical facial type with the change of airway volume and with the change of hyoid bone position.Conclusion: 1.class Ⅱ skeletal adult patients when vertical facial type changes,the volume of upper airway oropharyngeal section also changed,meaning that from low angle group to average angle group to high angle group,the volume reduced as the sequence,and there is obvious gap between low angle group,average angle group and high angle group,the gap has statistical significance.2.ClassⅡskeletal adult patients who have different vertical facial type,their hyoid bone position have obvious difference,consider Frankfort horizontal plane as datum plane,following the sequence from low angle group to average group to high angle group,the position of hyoid bone gradually moving to low and back direction.3.Hyoid bone position statistical analysis of Male group comparing with female group,showing that the vertical and horizontal gap between anterior basal plane is obviously increased for high angle group and average angle group,meaning that male’s high angle group and low angle group is closer to front and bottom direction comparing with female’s group.But the difference between low angle groups has no statistical significance. |
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