Fractal analysis of jawbone structure in patients with rheumatoid arthritis

Periarticular and generalized osteoporosis are well-known comorbidities of rheumatoid arthritis (RA), associated with either the disease itself or glucocorticoid therapy. This study was performed to quantitatively evaluate changes in the jawbones of patients with RA using fractal analysis (FA).

The study comprised 186 participants, including 144 women and 42 men. Of these, 93 were patients with RA and 93 were healthy controls. For the RA group, disease duration, laboratory findings, and medication use were recorded. Measurements of fractal dimension (FD), lacunarity (Lac), bone area fraction (BA/TA), and trabecular thickness (Tb.Th) were taken at the mandibular condyle and angle. These measurements were obtained from panoramic radiographs using ImageJ version 1.52p (National Institutes of Health, Bethesda, MD, USA).

Relative to control participants, patients with RA exhibited higher FD values for both mandibular condyle and angle regions (P<0.05). Conversely, the RA group displayed lower Lac values for both regions (P<0.05). Similarly, Tb.Th values were significantly lower in the RA patient group for both the condyle and the angle (P<0.05). Furthermore, a significant negative correlation was identified between disease duration and FD at the mandibular condyle (P<0.05).

The results demonstrate that FA can be used to quantitatively assess changes in trabecular bone in the jawbones of patients with RA. Image analysis parameters derived from panoramic radiographs, including FA, Lac, BA/TA, and Tb.Th, hold promise in guiding patients with RA toward appropriate medical examinations.