Analysis of changes in bone mineral density and cortical bone thickness after reconstruction of the mandible with fibula, is condyle preservation a critical influence factor?

OBJECTIVE: This study aimed to investigate the features of bone mineral density (BMD) and cortical bone thickness in grafted fibula. MATERIALS AND METHODS: Eighty-six patients who underwent mandibular reconstruction using vascularized fibula flaps were enrolled, all of whom were followed up at 3, 6, and 12 months after surgery. The patients were grouped according to whether the condyle was preserved. BMD and cortical bone thickness were also measured. RESULTS: Condyle-preserved group consisted of 65 patients and condyle-unpreserved group consisted of 21 patients. There was a significant correlation between thickness and BMD, which was significantly correlated with follow-up time. One year after surgery, the BMD of the condyle-preserved group decreased from 1029.61 +/- 156.01 mg/cm(3) to 978.6 +/- 141.90 mg/cm(3), and thickness decreased from 3.29 +/- 0.65 mm to 2.72 +/- 0.72 mm. BMD of the condyle-unpreserved group decreased from 1062.21 +/- 126.01 mg/cm(3) to 851.26 +/- 144.38 mg/cm(3), and thickness decreased from 3.46 +/- 0.89 mm to 2.56 +/- 0.73 mm. In the condyle-preserved and unpreserved groups, the absorption rates of BMD were 3.29 +/- 11.97% and 17.09 +/- 12.42% at 12 months, respectively, and the rate of thickness was 20.7 +/- 11.45% and 26.39 +/- 12.23% at 12 months, respectively. CONCLUSION: BMD and thickness showed a decreasing trend over time. Preserving the condyle can slow bone resorption of the fibula. Regarding implant restoration, we recommend doctors to perform the treatment within 6-12 months after surgery in order to effectively manage bone resorption. CLINICAL RELEVANCE: Our study found that condylar preservation can decrease the absorption rate of BMD and cortical bone thickness, helping doctors make better clinical decisions. TRIAL REGISTRATION NUMBER: ChiCTR2300069661 (March 22, 2023).