CBCT研究阻生尖牙与正常尖牙根尖位置的差异

目的 本研究利用正常萌出尖牙的根尖位置确定牙弓形态, 确定阻生尖牙与正常萌出尖牙根尖位置的差异, 并试图确定唇腭侧阻生尖牙的根尖位置是否存在差异。方法 21例正常未萌出的尖牙、19例腭侧阻生尖牙、16例牙槽窝阻生尖牙、25例唇侧阻生尖牙。采用锥形束计算机断层扫描获得图像, 利用Planmeca Romexis 3D软件确定根尖的X、Y、Z坐标。通过在腭平面上投影, 将获得的三维坐标转换为二维坐标, 对转换后的二维坐标进行处理, 一元二次项函数拟合绘制根尖弓形图。结果 4组根尖弓形图分布不同。腭侧组的阻生尖牙与对侧非阻生尖牙的位置有明显差异(P＜0.05);牙槽窝组的阻生尖牙与对侧非阻生尖牙的位置无差异(P＞0.05);腭侧组与牙槽窝组、唇侧组的阻生尖牙位置存在显著差异, 有统计学意义(P＜0.05);唇侧组与牙槽窝组的阻生尖牙位置无统计学差异(P＞0.05)。阻生尖牙根尖距离弓形的平均距离最远5.60 mm, 阻生尖牙根尖分布更倾向于第一前磨牙根尖的位置。结论 未完全钙化的未萌出牙齿在随后正常萌出中呈现出正常的根尖弓形。阻生尖牙根尖距离弓形的距离远于非阻生尖牙, 腭侧组的阻生尖牙根尖分布与其他阻生尖牙组不同。

The study of the difference between the apical position of impacted canines and normal erupted canines by CBCT

Objective In this study, the shape of the dental arch was determined by using the root apices of normal erupted canines, so as to determine the difference between the root apices of impacted canines and those of normal erupted canines.In addition, we attempted to determine whether the labio-palatal position of the impacted canines have difference.Methods The study included 21 normal unerupted canines (normally erupted canines of the permanent teeth), 19 palatal impacted canines, 16 midalveolus impacted canines, and 25 labial impacted canines.Images were obtained by conical beam computed tomography (CBCT), and the X, Y, and Z coordinates of root apices were determined by Planmeca Romexis 3D software.By projecting on the palatal plane, the obtained three-dimensional coordinates were converted into two-dimensional coordinates, and the converted two-dimensional coordinates were processed, univariate quadratic function to fit apical arch.Results Four groups of root apex arch have different distributions, there were significant differences between the impacted canines in the palatal group and the contralateral normal canines(P＜0.05).There was no difference between the impacted canines in the midalveolus group and the contralateral normal canines(P＞0.05).There were significant differences in the position palatal of the impacted canines between the midalveolusand labial groups(P＜0.05).There was no significant difference in the position of the impacted canines between the labial and midalveolus groups(P＞0.05).The average distance from the apex of the impacted canine was 5.60 mm, the apex of the impacted canine tends to be located at the apex of the first premolar.Conclusion Incompletely calcified, unerupted teeth with a subsequent normal eruption showed a normal arch form of the root apices.The root apices of impacted canines were farther from the arch forms than were the nonimpacted canines.Also, the root apices of impacted canines in the palatal area showed distributions different from those of the other impacted canine groups.