不同矢状骨面型错牙合的r角测量

背景：在错牙合畸形的诊断和治疗中,准确地描述颌骨的矢状向关系具有重要的意义。目前的评价方法均存在一定的不足。目的：介绍一种新的头影测量方法r角,以准确反映上下颌骨矢状向关系。方法：对180例13~25岁错牙合畸形青少年患者拍摄头颅侧位片进行头影测量分析,按照4项标准分为3组,确定不同的错     牙合畸形类型,分析男女差异。结果与结论：①骨型Ⅰ类错牙合的r值为(40.84±3.10)°,骨型Ⅱ类错牙合的r值为(48.85±3.09)°,骨型Ⅲ类错牙合的r值为(26.12±4.76)°。②各组r值在性别上差异无显著性意义。提示r角能够反映上下颌骨矢状方向不调,具有较好的可重复性。r值在35°~45°之间为骨型Ⅰ类错牙合,小于35°为骨型Ⅲ类错牙合,大于45°为骨型Ⅱ类错牙合。 

r angle measurement of the different sagittal skeletal pattern

BACKGROUND: An accurate anteroposterior measurement of jaw relationships is critically important in orthodontic diagnosis and treatment planning. There are some disadvantages in current cephalometric methods.OBJECTIVE: To introduce a new cephalometric measurement, named the r angle, in order to express the sagittal relationship between maxilla and mandible with accuracy and reproducibility.METHODS: One hundred and eighty patients aged 13-25 years were selected to take the pre-treatment cephalometric radiographs. They were divided into skeletal Ⅰ, Ⅱ, and Ⅲ groups on the basis of four standards. The different malocclusion types for the r angle were calculated. Finally, the differences between genders were analyzed. RESULTS AND CONCLUSION: ①The r values of skeletal Ⅰ, Ⅱ, and Ⅲ were (40.84±3.10)°, (48.85±3.09)° and (26.12±4.76)° respectively. ②There were no statistically significant differences of r value between genders. It indicates that r angle can express the sagittal relationship with good repeatability. r angle between 35 and 45 degrees can be considered to have a Class Ⅰ skeletal pattern. With an angle less than 35 degrees, patients are considered to have a skeletal Class Ⅲ relationship and with an angle greater than 45 degrees, patients have a skeletal Class Ⅱ relationship.