减数矫治影响口咽气道结构变化相关颅颌面特征因素和治疗设计因素的探讨

Narrow upper airway is a major cause of Obstructive Sleep Apnea Syndromes. Previous researches have found that the oropharyngeal airway is the most vulnerable part of obstruction, surrounding with soft tissues which changes are closely related to the craniofacial hard tissue. The incidence of craniofacial malocclusion shows an increasing tendency as the human chewing dysfunction throughout the human evolution. Most people with malocclusion requires orthodontic treatment, while domestic statistical data shows that over 50% of patients with malocclusion are in need of treatment with extraction. After extraction treatment, the decreasing in the sagittal diameter of the oropharyngeal airway was observed clinically, especially in those cases of en-mass retraction of anterior teeth by strong anchorage. However,scant reports in this area was found both in and abroad, several researches of three-demensional Cone-beam CT (CBCT) have been reported these two years. In addition, the role of crniofacial character and extraction mode,different anchorage design in treatment planning in the decreasing of the oropharyngeal airway is not clarified. And the mechanism whether the changes of oropharyngeal airway correlated to some craniofacial structure altering are still unknown. Moreover, there is no sreies report focus on this point using three-dimensional method. .In this study, Adolescent patients with Angle class I and class II1 malocclusion treated with symmetrically extraction will be randomly choosed as study sample. Accompanied age and sex-matched Angle class I patients with non-extraction as control sample. CBCT image data will be obtained before and after conventional orthodontics treatment. And the craniofacial hard and soft tissues and oropharyngeal airway will be established after three-dimensional reconstruction using professional dental software. The character of the oropharyngeal airway changes will be analyzed, to find the closely correlative factors of craniofacial structure as well as the treatment planning impact on the changes of oropharyngeal airway. Clarifing the mechanism of the morphological changes of the upper airway during extraction treatment will provide clinical guidance for extraction treatment plan.

上气道狭窄是阻塞型睡眠呼吸暂停综合征的主要病因，最易发生阻塞的口咽气道变化与颅颌面软硬组织结构紧密相关。错合畸形发生率随人类咀嚼功能减退呈现增高趋势，目前超过50%的就诊错合畸形患者需要进行减数矫治。临床观察发现减数矫治后（尤其强支抗下）口咽气道矢状径呈现减小趋势。关于减数矫治对上气道的影响，国内外文献报道较少，近年出现了将三维锥体束CT(CBCT)用于研究上气道结构变化的相关报道，但减数矫治中颅颌面软硬组织结构特征及其变化和减数模式、支抗设计等治疗设计因素对口咽气道变化的影响机制未予阐明。本研究纳入安氏I类和II1类生长发育期患者，获取常规减数矫治前后的CBCT数据，使用三维测量软件对颅颌面软硬组织和口咽气道进行重建及测量，明确减数矫治后口咽气道的特征变化，探讨颅颌面结构特征及治疗设计因素对口咽气道变化的影响，明确减数矫治对口咽气道形态变化的作用机制，指导正畸临床减数矫治方案的制定。

临床入组的69例年龄介于11-30岁的正畸患者, 采用CBCT三维成像系统和三维头影测量分析，配合三维模型测量分析方法，测量分析了口咽气道容积与结构指标9项、颅颌面硬组织指标22项、气道周围软组织指标6项和上下颌模型指标14项。对照研究发现年龄、性别严格配比的骨性I类和骨性II类错颌畸形患者矫治前口咽气道容积、长度和最小横截面积均无显著性差异，身高对生长发育期患者的口咽气道容积和结构有明显的影响。运用逐步后退法建立多重线性回归方程，筛选出与口咽气道容易密切相关的颅颌面软硬组织结构指标包括合平面、L1-NB角度和线距、Wits值、下磨牙区牙弓宽度、舌体长度、Y-Axis、U1-NA线距、L1-MP、NA-PA、SNA等。CBCT拍照时的头位对口咽气道结构并无明显的影响。经年龄和性别配比的不同减数模式和支抗强度组患者在治疗中，减数矫治引起口咽气道容积和结构变化的评价，以及在治疗中影响口咽气道变化的减数模式、支抗强度和相关软硬组织特征性指标需要治疗完成的数据分析得出结论。. 在此前期研究基础上，我们将进一步探讨软腭和舌体容积的测量评价方法，发现减数矫治后牙弓内容积改变对软腭和舌体的作用，或者说判断软腭和舌体如何适应性改变的问题；增加横径/矢状径等指标更明确气道结构和形态的改变，以判断减数矫治对与口咽气道变化影响的作用机制；将患者BMI指数和颈围纳入对气道容积和三维结构影响的研究。