Serrant Paul S, McIntyre Grant T, Thomson Donald J
G. McIntyre, Department of Orthodontics, NHS Tayside, 2 Park Place, Dundee DD1 4HR, UK
J Orthod. 2014 Mar;41(1):13-8. doi: 10.1179/1465313313Y.0000000076.
To compare the accuracy of cone-beam CT (CBCT) with conventional horizontal and vertical parallax for the localization of ectopic maxillary canines.
Observational study.
A typodont was constructed using human teeth embedded in radio-dense impression material, containing a simulated ectopic canine. Image sets (vertical/horizontal parallax and CBCT scans) were obtained for nine positions. A photograph confirmed the true position of the canine. Six observers used horizontal (HP) and vertical (VP) parallax techniques with conventional radiographs and the axial, coronal and sagittal CBCT views to locate the canine tip. Images were manipulated as required using proprietary software (http://www.carestream.com and http://www.i-cat.com). Intra-observer reproducibility was calculated by one observer re-evaluating the image sets after 2 months. Individual observer validity was calculated in relation to the photographic position of the canine using weighted Kappa. Differences in the proportion of correct locations between CBCT and vertical/horizontal parallax were tested using McNemar tests (P<0·05).
Intra- and inter-observer agreements were excellent (0·8985) and substantial (0·7528), respectively. Individual observer validity was substantial-excellent (0·7368-0·900). The canine position was correctly identified in 94% of cases located using CBCT, 83% using HP and 65% using VP. The differences between CBCT and vertical and horizontal parallax were highly statistically significant (P<0·01).
CBCT is more accurate than either horizontal or vertical parallax for the localization of ectopic maxillary canine teeth.
比较锥形束CT（CBCT）与传统水平和垂直视差法在上颌异位尖牙定位中的准确性。
观察性研究。
使用嵌入放射致密印模材料中的人类牙齿构建一个牙模型，其中包含一颗模拟的异位尖牙。针对九个位置获取图像集（垂直/水平视差和CBCT扫描）。一张照片确定了尖牙的真实位置。六名观察者使用传统X线片的水平（HP）和垂直（VP）视差技术以及CBCT的轴向、冠状和矢状视图来定位尖牙尖端。根据需要使用专有软件（http://www.carestream.com和http://www.i-cat.com）对图像进行处理。由一名观察者在2个月后重新评估图像集来计算观察者内的可重复性。使用加权Kappa计算各个观察者相对于尖牙照片位置的有效性。使用McNemar检验（P<0.05）测试CBCT与垂直/水平视差之间正确定位比例的差异。
观察者内和观察者间的一致性分别为优秀（0.8985）和显著（0.7528）。各个观察者的有效性为显著-优秀（0.7368 - 0.900）。使用CBCT定位的病例中，94%正确识别了尖牙位置，使用HP为83%，使用VP为65%。CBCT与垂直和水平视差之间的差异具有高度统计学意义（P<0.01）。
在定位上颌异位尖牙方面，CBCT比水平或垂直视差法更准确。
