Buchgreitz J, Buchgreitz M, Mortensen D, Bjørndal L
Private practice, Allerød, Denmark.
Section of Cariology & Endodontics, Department of Odontology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
Int Endod J. 2016 Aug;49(8):790-5. doi: 10.1111/iej.12516. Epub 2015 Aug 22.
To evaluate ex vivo, the accuracy of a preparation procedure planned for teeth with pulp canal obliteration (PCO) using a guide rail concept based on a cone-beam computed tomography (CBCT) scan merged with an optical surface scan.
A total of 48 teeth were mounted in acrylic blocks. An apical canal preparation was created to simulate remnants of an apical root canal that acted as the target for a drill path. The test blocks were surface scanned, and merged with a CBCT scan, and a guide rail was made. A pathway for the bur was created through a metal sleeve within the guide rail into dentine. The distance was measured between the centres of the performed drill path and the apical target by two examiners. A maximum distance of 0.7 mm was defined based on the radius of the bur (0.6 mm) and the radius of a root canal just visible on a radiograph (0.1 mm). The t-test was used for evaluation, and intra- and inter-examiner reproducibility was expressed by intraclass correlation coefficients.
The mean distance between the drill path and the target was significantly lower than 0.7 mm, and null hypothesis H0 : μ = 0.7 was rejected (CI 95%: 0.31;0.49, P < 0.001). Intra- and inter-examiner agreements reached excellent levels.
The combined use of CBCT and optical scans for the precise construction of a guide rail led to a drill path with a precision below a risk threshold. The present technique may be a valuable tool for the negotiation of partial or complete pulp canal obliteration.
在体外评估一种针对牙髓腔闭锁（PCO）牙齿设计的预备程序的准确性，该程序采用基于锥形束计算机断层扫描（CBCT）与光学表面扫描融合的导轨概念。
将48颗牙齿固定在丙烯酸块中。制备根尖根管预备以模拟根尖根管的残余部分，作为钻孔路径的目标。对测试块进行表面扫描，并与CBCT扫描融合，制作导轨。通过导轨内的金属套管在牙本质中为车针创建一条路径。由两名检查者测量所执行的钻孔路径中心与根尖目标之间的距离。根据车针半径（0.6mm）和X线片上刚可见的根管半径（0.1mm）定义最大距离为0.7mm。采用t检验进行评估，组内相关系数表示检查者内和检查者间的可重复性。
钻孔路径与目标之间的平均距离显著低于0.7mm，原假设H0：μ = 0.7被拒绝（95%置信区间：0.31；0.49，P < 0.001）。检查者内和检查者间的一致性达到了优秀水平。
联合使用CBCT和光学扫描精确构建导轨可使钻孔路径精度低于风险阈值。本技术可能是处理部分或完全牙髓腔闭锁的一种有价值的工具。
