The Effect of Alteration of the Exposure Parameters of a Cone-beam Computed Tomographic Scan on the Diagnosis of Simulated Horizontal Root Fractures

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The purpose of this study was to determine the effect of alteration of the exposure parameters of a cone-beam computed tomographic (CBCT) scan on the detection of the presence or absence of simulated horizontal root fractures (HRFs).


CBCT scans of the lower incisor region of 5 human, dentate, dry mandibles were performed with 11 different exposure parameters. Ten teeth were extracted, and simulated HRFs were created near the apical thirds of the root. The fragments were reattached and the teeth replanted. The mandibles were rescanned over the same range of exposure parameters. Receiver operator characteristic analysis and kappa analyses were performed to assess diagnostic accuracy and intra- and interexaminer agreement for each scan setting.


The overall Az value (area under receiver operator curve) for the manufacturer's default setting was 0.95. The sensitivity was 0.94 and the specificity 0.96. A reduction in the tube current to 2 mA at 360° or 180° of rotation had no significant impact on the Az value, sensitivity, or specificity of CBCT imaging in the detection simulated HRFs. A reduction in the current to 1 mA at 360° or 180° of rotation significantly reduced the Az value (0.9 and 0.75, respectively) in comparison with the manufacturer's default setting (P < .05).


CBCT scans are an accurate and reliable technique to detect HRFs. Within the limitations of this study, it is possible to reduce the radiation dose by altering the exposure parameters without a significant reduction in the diagnostic quality of the CBCT scan generated for the detection of HRFs.

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