I would like to congratulate Dr Kumar et al for their effort in the preparation of their manuscript, “Comparison between cone-beam computed tomography and intraoral digital radiography for assessment of tooth root lesions” (Kumar V, Gossett L, Blattner A, Iwasaki LR, Williams K, Nickel JC.Am J Orthod Dentofacial Orthop 2011;139:e533-e541). The development of CBCT dedicated to dental and maxillofacial imaging has made it possible to obtain a 3-dimensional image of 1 tooth with reduced effective radiation doses, shorter acquisition scan times, easier imaging, and lower costs than medical CT systems.
CBCT outperformed 2-dimensional techniques in most diagnostic tasks such as assessment of periapical lesions, root fractures, periodontal defects, and root resorption. However, the authors of this study did not show any difference between conventional intraoral radiography and CBCT. This conclusion can be misleading and is most likely related to study design.
First, only 10 teeth were used, and the same teeth were used as the controls and the diseased examples; this could cause recall of the images. Second, statistical analysis by using the chi-square test and giving only percentages for accuracy was inappropriate. In addition, all images obtained from the 2 modalities were assessed in the same session; this complicated the comparison. Another important factor was the selection of lesion size. Large lesions are easily detectable by all radiographic techniques. In this study, the selected round burs were relatively large, and that did not allow an objective comparison.
Finally, large fields of view do not allow reconstructions with small voxel sizes. Newer CBCT systems offer smaller voxel sizes with decreased fields of view that facilitate better observer performance and lower patient doses. For assessing dental lesions, which require detailed images for root resorption, limited fields of view with small voxels would be beneficial. Since most orthodontic patients are children and a large field of view is necessary for orthodontic purposes, clinicians must use caution when prescribing CBCT for orthodontic patients.