Análise de imagem de lesões fibro-ósseas

Abstract

Fibro-osseous lesions (FOLs) are characterized by the replacement of normal bone with fibrous connective tissue and mineralized material. The group includes the fibrous dysplasia, ossifying fibroma and cemento-osseous dysplasia (COD). These three lesions show similar histopathological and radiographic features. Clinical, radiographic and histopathological data correlation is necessary for the definitive diagnosis. This study aimed to describe and to evaluate dental imaging exams of individuals diagnosed with FOLs. Three studies with independent methodologies were developed. The first study evaluated the effects of COD on the adjacent anatomical structures by means of cone beam computed tomography (CBCT). Sixty cases of COD were evaluated. The assessment of the 60 cases involved 244 lesion areas and 426 teeth. Most lesions presented nearly 10 millimeters (mm) of diameter. Thinning (n=80), expansion (n=62) and perforation (n=60) were common effects on the cortical bone. All 426 teeth presented discontinuation of the lamina dura and of the periodontal ligament space. In the second study, 50 panoramic radiographies of women diagnosed with COD were matched with 50 panoramic radiographies of women without COD according to the individuals’ age. Comparisons between groups regarding the mandibular cortical width index (MCW), the fractal dimension (FD) of the region of the trabecular and the cortical bone and the mandibular cortical index (MCI) were carried out. The MCW of the COD group was 3.12 mm (2.15-4.55) and the MCW of the non-COD group was 3.52 mm (1.90-4.70). A significant difference between groups was observed (p=0.034). FD of the normal trabecular alveolar bone was similar in both groups. For the cortical bone, a lower mean FD was observed in the COD group (p=0.046). The MCI C3 was more common in the COD group (p=0.009). The third was a preliminary study, in which the FD was evaluated on twodimensional and three-dimensional CBCT images of six cases of fibrous dysplasia and six cases of ossifying fibroma. Panoramic reconstruction, axial, coronal and sagittal slices were selected in four thicknesses (0.25, 5, 15 and 25 mm) and evaluated in three shapes of regions of interest (ROI). Two methodologies compared four volume formats from inside the lesions. A significant difference between fibrous dysplasia and ossifying fibroma was observed for the mean FD of the twodimensional images of panoramic reconstruction and axial slices with a thickness of 0.25 mm (p<0.05), regardless of the ROI shape (p>0.05). The mean DF of threedimensional images was different between lesion groups for most comparisons (p <0.05), regardless of the methodology used. Detailed information on lesions and involvement of adjacent structures can be viewed in CBCT. Non-invasive methods, such as radiomorphometric indices and fractal analysis may be useful in the detection of low bone mineral density or as a helpful tool for the differentiation of distinct types of FOLs.