Comparison of fractal analysis in panoramic radiography and panoramic reconstructions obtained by cone beam computed...

The aim of this study was to compare the use of panoramic radiography (PAN) and panoramic reconstructions obtained from cone beam computed tomography (CBCT) for the evaluation of trabecular bone structure using fractal dimension (FD).

This cross-sectional study evaluated PAN and CBCT images of 20 patients. In each tomographic volume, panoramic reconstructions were obtained with the following thicknesses: 160 µm; 480 µm; 800 µm; 1.1 mm; 2.1 mm; 3.0 mm; 4.0 mm; 5.0 mm; 10.1 mm; 14.9 mm; 20.0 mm; 29.9 mm; 40.2 mm, and 50.1 mm. For each image acquired, the FD value of the regions of interest (ROI) was calculated by the White and Rudolph technique. Six ROIs of 40 × 40 pixels were manually selected 2 mm superior, 2 mm anterior and 2 mm inferior to the mental foramen.

The results were statistically significant for the FD values obtained from the different exams evaluated (p < 0.001) and for the ROIs analyzed (p = 0.021). However, when the type of imaging exam and the ROIs were compared, no significant difference was observed between the groups (p = 0.993). Regarding the different panoramic reconstruction thicknesses, a difference was observed between the thinner reconstructions (160 µm and 480 µm) and the thicker reconstructions (29.9 mm; 40.2 mm and 50.1 mm) (p < 0.001).

There are differences between the FD values obtained from PAN and panoramic reconstructions from CBCT, and differences between ROIs within the same imaging exam.