Evaluation of changes after orthognathic surgery in mandibular alveolar and interdental structures via fractal analysis

Objective: In adults, skeletal anomalies of the mandible are treated with orthognathic surgery. Adaptive changes in mandibular trabecular structures are observed in the post-surgical period. The aim of this study is to evaluate mandibular trabecular bone in the vertical incision line damaged after orthognathic surgery, along with the condyle and canine regions, using Fractal analysis. Materials and Methods: The study population consisted of patients who presented to the Department of Orthodontics at Yeditepe University Faculty of Dentistry with a diagnosis of mandibular prognathism or retrognathism between January 2019 and January 2023 and underwent BSSRO (Bilateral Sagittal Split Ramus Osteotomy) surgery under general anesthesia. The study included 42 patients (17 males, 25 females). Patients with pre- and post-operative panoramic radiographs were divided into two groups. In Group I, panoramic radiographs taken within the first four months after surgery were examined, while in Group II, panoramic radiographs of patients whose surgery had occurred between four and twelve months prior were examined. The box-counting method was used to evaluate changes in trabecular structure through Fractal analysis. P values less than 0.05 were considered statistically significant. Results: Fractal measurements revealed a statistically significant decrease in both right and left osteotomy lines in Group I (p < 0.001). While a statistically significant decrease was observed in the right condyle (p < 0.001), the change in the left condyle was not found to be statistically significant. In the canine region, a statistically significant decrease was observed on the left side (p < 0.024), while the change on the right side was not statistically significant. However, in Group II, the changes in all examined areas were not found to be statistically significant. Conclusion: The application of fractal analysis after orthognathic surgery allows for the evaluation of changes in mandibular bone trabeculae. It has been concluded that not only is there a decrease in bone trabeculae along osteotomy lines but also the canine and condyle regions may be affected. The healing process of the bone can be assessed through a combination of clinical data and fractal analysis. KeyWords: Fractal Analysis, Orthognathic Surgery, Mandibular Condyle, Trabecular Bone, Bone Healing