Evaluation of the effects of removable and fixed functional appliances applied during the pubertal and postpubertal periods on the mandibular bone using fractal analysis

Aim: This study evaluated skeletal and dentoalveolar effects of removable and fixed functional appliances in skeletal Class II patients during pubertal and post-pubertal periods using cephalometric analysis, and assessed mandibular trabecular changes by fractal analysis. Materials and Methods: Eighty individuals were classified by growth stage into four equal groups: Pubertal Monoblock, Post-Pubertal Monoblock, Pubertal Herbst, and Post-Pubertal Herbst. Fractal analysis and cephalometric measurements were made on panoramic and lateral cephalometric radiographs taken before (T0) and after (T1) treatment. The condyle, angulus, corpus and symphysis of the mandible were selected as regions of interest. Results: All groups showed a statistically significant decrease in FD values in the right and left condyle, corpus, and symphysis regions (p<0.05), while a significant increase was observed in the angulus region (p<0.05). The decrease in the condylar region was more pronounced in the pubertal groups (p<0.05). Individuals treated with the Monoblock appliance exhibited greater reductions in the corpus region, whereas the most prominent decrease in the symphysis region occurred in the Post-Pubertal Herbst group (p<0.05). Conclusion: Functional treatment in both periods produced changes in mandibular trabecular structure. The mandibular angulus, as the masseter muscle attachment area, was more resistant to resorption. More pronounced trabecular changes were observed in the condyle and angulus during puberty, while in the post-pubertal period lower incisor protrusion, particularly with Herbst therapy, led to greater trabecular alteration in the symphysis. The Monoblock appliance caused greater trabecular changes in the corpus, associated with selective grinding of the posterior acrylic component to induce extrusion. Keywords: Fractal analysis, functional appliance, Herbst appliance, monoblock appliance.