Fractal analysis of fibrous dysplasia and ossifying fibroma in 2D and 3D CBCT images

Objective: To assess the complexity of fibrous dysplasia and ossifying fibroma lesions by fractal dimension (FD) in 2D and 3D cone-beam computed tomography (CBCT) images.Methods: Six cases of fibrous dysplasia were compared with six cases of ossifying fibroma in different images, thicknesses and regions of interest (ROI) of 2D and 3D images. FD was determined separately in hypondense and hyperdense areas using the box-counting method. The Student t-test was applied to determine the difference in FD between lesion groups.Results: FD of hypodense areas in 2D images ranged from 1.2566 to 1.4532 in fibrous dysplasia and from 1.1540 to 1.3601 in ossifying fibroma, while FD of hyperdense lesion areas ranged from 1.1755 to 1.4132 for fibrous dysplasia and from 1.0480 to 1.2769 for ossifying fibroma images. Panoramic reconstruction and axial images of 0.25 mm thickness revealed significant differences between lesion groups in all ROI shapes (p < 0.05). FD of 3D images was higher in fibrous dysplasia (2.4999-2.7417) than in ossifying fibroma (1.9283-2.4144) in both hyperdense and hypodense areas, with statistical difference in almost all ROIs (p < 0.05).Conclusions: FD data suggest higher complexity of structures of fibrous dysplasia lesions than of structures of ossifying fibroma.