Detection of horizontal root fracture using four different protocols of cone-beam computed tomography

The purpose of this study was to analyze four different cone-beam computed tomography (CBCT) protocols to identify horizontal root fractures (HRF) in endodontically treated teeth, with or without the presence of a metallic post. Thirty extracted single-rooted human premolars were treated endodontically. Afterwards, an observer induced a horizontal fracture in 15 teeth. Each tooth was inserted in an empty mandibular socket and submitted to a computed tomography scan taken with and without the metallic post. The acquisition followed four different protocols, with different fields of view (FOV) and voxel sizes, as follows: FOV 6X16 cm/0.2 mm voxel; FOV 6X16 cm/0.25 mm voxel; FOV 8X8 cm/0.2 mm voxel; FOV 8X8 cm/0.25 mm voxel. Two observers checked all the acquisitions within a two-week interval, and the values of sensitivity, specificity, accuracy and kappa were calculated. The sensitivity, specificity and accuracy values were better for the 8X8 cm/0.2 mm and 16X6 cm/0.25 mm protocols, ranging from 0.60 to 0.86 and 0.53 to 0.80, respectively. The intra- and interobserver concordance ranged from 0.65 to 0.72. The protocols where FOV and voxel were proportional showed better results. The 8x8 cm/0.2 mm protocol had the least interference from the metallic artifact. All four protocols showed a decline in values in the presence of the metallic artifact.

本研究旨在分析四种不同的锥形束计算机断层扫描（cone-beam computed tomography，CBCT）方案，以识别经牙髓治疗的患牙（无论是否存在金属桩）的水平根折（horizontal root fractures，HRF）。本研究共纳入30颗拔除的人类单根前磨牙并完成牙髓治疗。随后，一名操作者对其中15颗牙齿制备人工水平根折。将每颗牙齿植入离体下颌牙槽窝内，分别在有无金属桩的条件下进行计算机断层扫描。扫描采用四种不同方案，配置不同的视野（field of view，FOV）与体素（voxel）尺寸，具体如下：6×16 cm视野/0.2 mm体素、6×16 cm视野/0.25 mm体素、8×8 cm视野/0.2 mm体素、8×8 cm视野/0.25 mm体素。两名观察者在两周间隔内对所有扫描图像进行阅片，并计算灵敏度、特异度、准确率及Kappa值。结果显示，8×8 cm/0.2 mm与6×16 cm/0.25 mm方案的灵敏度、特异度与准确率表现更优，其数值范围分别为0.60~0.86与0.53~0.80。观察者内部与观察者间的一致性系数介于0.65~0.72。视野与体素尺寸匹配的扫描方案整体效果更佳。其中8×8 cm/0.2 mm方案受金属伪影的干扰最小。四种扫描方案在存在金属伪影时，各项评估指标均出现不同程度的下降。