[Diagnostic accuracy of cone beam computed tomography and eight-slice computed tomography for evaluation of external...

To evaluate the diagnostic accuracy of cone beam computed tomography (CBCT) and high resolution multi-slice computed tomography (MSCT) with eight-detector-rows in detecting the simulated external root resorption defects.

External root resorption defects of different sizes and in different locations were simulated in 40 human single rooted teeth. Cavities simulating root resorption defects of 1 mm in diameter and 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm in depth were drilled in the cervical, middle and apical thirds of lingual surfaces of the teeth. The specimens were scanned with both CBCT (Accuitomo 3DX, Morita Co., Japan) and high resolution 8-slice CT (BrightSpeed Edge, GE Co., USA). The CBCT and MSCT images were read by two experienced observers. The data were analyzed with receiver operating characteristics (ROC) analysis. ROC curves were generated and the area under ROC curve (Az) was employed to express the diagnostic accuracy.

The diagnostic accuracy (Az value) in detecting the simulated defects of all the locations and sizes were 0.921 for CBCT and 0.770 for MSCT. The Az values for CBCT in detecting defects located in the cervical, middle and apical thirds were 0.885, 0.991 and 0.873, while those for MSCT were 0.752, 0.844 and 0.709, respectively. The Az values for CBCT in detecting the defects of 0.1 mm, 0.2 mm, 0.3 mm and 0.4 mm in depth were 0.794, 0.934, 0.992 and 0.992, and those for MSCT were 0.592, 0.719, 0.920 and 0.990, respectively.

The diagnostic ability for external root resorption of CBCT is better than that of MSCT. Smaller defects are better delineated with CBCT than with MSCT. The defects in the middle thirds of the roots are easier to be detected than those in the cervical and apical ones using both CBCT and MSCT.