The crown morphology of Norway spruce (Picea abies Karst) was studied from 617 sample trees. In order to model branch and crown descriptors the linear and nonlinear regression methods were extensively used. Results sh...The crown morphology of Norway spruce (Picea abies Karst) was studied from 617 sample trees. In order to model branch and crown descriptors the linear and nonlinear regression methods were extensively used. Results show that the branch length can be fairly well predicted from the distance to the apex of the tree and that the branch spread has a high correlation with the branch length and the insertion angle. Models have been set up to predict the crown ratio, height to the base of the living crown, height to the first living branch and the height to the first dead branch from the usual whole-tree measurements, namely diameter at breast height total height and total age.展开更多
目的:采用锥形束CT测量对不同垂直骨面型成人骨性Ⅱ类错[牙合]患者上颌尖牙冠根角及其周围骨结构进行分析。方法:采用KaVo 3D eXam CBCT机拍摄获得60名成人骨性Ⅱ类错[牙合]患者(年龄18~30岁)的颅颌面三维影像,根据头颅侧位片中FMA、SN...目的:采用锥形束CT测量对不同垂直骨面型成人骨性Ⅱ类错[牙合]患者上颌尖牙冠根角及其周围骨结构进行分析。方法:采用KaVo 3D eXam CBCT机拍摄获得60名成人骨性Ⅱ类错[牙合]患者(年龄18~30岁)的颅颌面三维影像,根据头颅侧位片中FMA、SN-MP角的大小分为低角组(n=16)、均角组(n=25)、高角组(n=19),对上颌双侧尖牙冠根角、牙槽骨附着高度、牙槽骨厚度等进行测量。结果:3组患者上颌尖牙唇、腭侧牙槽骨附着高度以及唇侧牙槽嵴顶水平牙槽骨厚度差异无统计学意义(P均>0.05)。上颌尖牙根尖水平唇、腭侧及总牙槽骨厚度高角组<均角组<低角组(P均<0.05)。上颌尖牙唇、腭侧旋转移动距离和最大旋转距离高角组<均角组<低角组(P均<0.05)。上颌尖牙冠根角高角组>均角组>低角组(P<0.05)。结论:不同垂直骨面型成人骨性Ⅱ类错[牙合]患者上颌尖牙冠根角及周围骨结构存在差异,正畸矫治过程中进行牙体移动设计时应多加注意。展开更多
文摘The crown morphology of Norway spruce (Picea abies Karst) was studied from 617 sample trees. In order to model branch and crown descriptors the linear and nonlinear regression methods were extensively used. Results show that the branch length can be fairly well predicted from the distance to the apex of the tree and that the branch spread has a high correlation with the branch length and the insertion angle. Models have been set up to predict the crown ratio, height to the base of the living crown, height to the first living branch and the height to the first dead branch from the usual whole-tree measurements, namely diameter at breast height total height and total age.
文摘目的:采用锥形束CT测量对不同垂直骨面型成人骨性Ⅱ类错[牙合]患者上颌尖牙冠根角及其周围骨结构进行分析。方法:采用KaVo 3D eXam CBCT机拍摄获得60名成人骨性Ⅱ类错[牙合]患者(年龄18~30岁)的颅颌面三维影像,根据头颅侧位片中FMA、SN-MP角的大小分为低角组(n=16)、均角组(n=25)、高角组(n=19),对上颌双侧尖牙冠根角、牙槽骨附着高度、牙槽骨厚度等进行测量。结果:3组患者上颌尖牙唇、腭侧牙槽骨附着高度以及唇侧牙槽嵴顶水平牙槽骨厚度差异无统计学意义(P均>0.05)。上颌尖牙根尖水平唇、腭侧及总牙槽骨厚度高角组<均角组<低角组(P均<0.05)。上颌尖牙唇、腭侧旋转移动距离和最大旋转距离高角组<均角组<低角组(P均<0.05)。上颌尖牙冠根角高角组>均角组>低角组(P<0.05)。结论:不同垂直骨面型成人骨性Ⅱ类错[牙合]患者上颌尖牙冠根角及周围骨结构存在差异,正畸矫治过程中进行牙体移动设计时应多加注意。
