Evaluation of the effects of removable and fixed functional appliance treatments on mandibular bone using fractal analysis method

Aim: The aim of this study is to evaluate the changes occurring in the mandibular trabecular bone after treatment with removable and fixed functional appliances in patients with skeletal Class II malocclusion during the pubertal growth period, using the Fractal Analysis (FA) method with panoramic and lateral cephalometric radiographs. Materials and Methods: Panoramic and cephalometric images of 120 individuals with skeletal Class II malocclusion and normodivergent vertical growth patterns in the pubertal growth period were divided into four groups. The study groups consisted of three treatment groups of 30 patients each, treated with Monoblock, Twin-block, and Herbst appliances. The control group included 30 untreated individuals. Changes in the mandibular condyle, angle, corpus, and symphysis regions after functional treatment were evaluated using the FA method in all individuals. Results: A statistically significant decrease in fractal dimension (FD) values was observed in the condyle, corpus, and symphysis regions of all individuals in the treatment groups (p<0.05). However, a statistically significant increase in FD values was noted in the angle region for all treatment groups (p<0.001). No statistically significant difference was found in the FD values between the beginning and end of the study period for individuals in the control group (p>0.05). Conclusion: Fixed and removable functional appliance treatments applied during the pubertal period reshape the mandibular condyle, allowing it to be positioned more anteriorly. Additionally, it was observed that the angle region, influenced by the fibers of the masseter muscle attached to the mandible, forms a resistant area to resorption. In treatments involving removable appliances, a decrease in trabecular bone density in the mandibular corpus region occurred, likely due to the acrylic mass in the posterior region and selective grinding applied for the extrusion of posterior teeth. The increase in lower incisor angles observed as a side effect of removable and fixed functional treatments is thought to cause a reduction in trabecular bone density on the buccal side of incisor roots. Key Words: Functional Appliances, Fractal Analysis, Trabecular Bone, Panoramic Radiography, Cephalometric Radiography.