采用锥形束CT测量牙体长度的准确性研究

Investigation of accuracy of premolar length measured by cone beam CT in vivo

目的探索锥形束CT（CBCT）对牙体长度各参数测量的可行性及准确性。方法通过InVivoDental软件对40例患者109颗活体牙的CBCT扫描数据进行组织分割以及重建，得到目标牙长轴的颊舌向断层图像，测量根长、冠长和牙体全长。相同活体牙经外科拔除后，进行相应参数测量。比较实体测量值和CBCT测量值的差异，检验CBCT测量牙体长度的精确性。结果实验牙根长、冠长及牙体全长的CBCT测量值与实体测量值的差异无统计学意义（P值分别为0．790、0．621、0．657），两种测量方法差值的95％可信区间分别为（-1．10～1．13）、（-1．00～0．96）、（-1．00～1．05）mm。结论CBCT对活体牙的根长、冠长及牙体全长的无创测量与实体测量的一致性较好，可在临床推广应用。

Objective To investigate the feasibility and accuracy of length measurement of in vivo teeth by using cone beam CT （CBCT）. Methods Before orthodontic extraction, 109 vital premolars from 40 participants were scanned by using CBCT and reconstructed by using InVivoDental software. Buccal-lingual sectional images along the long axis of teeth were then acquired, and the crown, root, and tooth length were measured separately. After careful extraction and fixation, the cor- responding length of the same tooth was measured by using a digital caliper. CBCT measurement accuracy was then verified by using physical measurements as reference. Results CBCT and the physical method did not obtain significantly different measurements of the root, crown, and tooth length of experimental teeth （P=0.790, P=-0.621, P=0.657, respectively）, and the measurements were found to be consistent. The 95% limits of agreement of root, crown, and tooth length were -1.10 mm to 1.13 mm, -1.00 mm to 0.96 ram, and -1.00 mm to 1.05 mm, respectively. Conclusion The difference between CBCT and the physical method was not significant, and good consistency was shown. CBCT could be applied in noninvasive measure- ment of in vivo teeth.