Evaluation of mandibular condyle trabecular structure in patients with rheumatoid arthritis using fractal analysis

Fractals are complex geometric shapes with self-similarity when evaluated at different scales. In recent studies, fractal analysis method is used in the diagnosis and follow-up of systemic diseases. Rheumatoid arthritis (RA) causes periarticular and general osteoporosis. In this study, mandibular condyle trabecular structure was evaluated by fractal analysis on the panoramic radiographs of RA patients that grouped via Dual energy X-ray absorptiometry (DEXA) scans' results. In addition, the correlation between the femoral neck and L1-L4 lumbar vertebrae T scores and the fractal dimension (FD) value of each patient was evaluated. This retrospective study included 100 RA patients with DEXA screening. Patients were divided into three groups as 33 normal, 33 osteopenic and 34 osteoporotic RA according to DEXA results. The control group was composed of 33 people with normal values and in accordance with the gender and age criteria of the patient group. Panoramic radiographs of the patients were transfered in ImageJ v1.52a program and fractal dimension of the trabecular structure of the mandibular condyle was calculated. The data were analyzed using SPSS (v24). As a result of the analysis, the mean FD values of both condyle of the patient group were lower than the control group (p<0.001). When the mean of FD values of condyle of the normal, osteopenic, osteoporotic RA patients and control group was compared, there was no statistically significant difference between the RA groups (p>0.05), while the FD values of the control group were found statistically significantly higher than the RA groups (p<0.05). No statistically significant difference was found between femoral neck and L1-L4 lumbar vertebra T scores and FD values in the patient and control groups (p>0.05). According to the study, it has been determined that the separation of RA patients and healthy people can be made using fractal analysis using panoramic radiography. No correlation between DEXA results and FD values suggested that small joints were more affected by the disease. As a result, if the DEXA scan can be applied to the mandibular condyle, the comparison between FB-DEXA is thought to be more meaningful.