PurposeTo evaluate the effects of concentrated growth factor (CGF), combined with a mixture of iliac cancellous and composite bone materials, on the repair of extensive mandibular defects. Patients and MethodsThis clinical trial involved patients with mandibular defects caused by large cystic lesions. The test group comprised 16 patients who underwent CGF combined with iliac cancellous bone and composite bone materials to repair extensive mandibular defects, whereas the control group comprised eight patients who underwent vascularised free fibula grafts for mandibular segmental defects. Postoperative exudatum was collected from patients on the 1st, 2nd, 3rd, and 4th days postoperatively, and osteogenic factor, including alkaline phosphatase (ALP), osteocalcin (BGP), and procollagen type I N-terminal propeptide (PINP), and inflammatory cytokines were performed. Additionally, regular cone beam computed tomography (CBCT) scans were conducted before and after surgery. ResultsOn postoperative days 1–4, the expression levels of ALP, BGP, and PINP were higher in the test group, while those of IL-1α, IL-1β, IL-6, IL-8, and TNF-α, which were identified as co-differentially expressing inflammatory cytokines, were all down-regulated in the exudatum of the test group. Regular CBCT radiological scans revealed a significant osteogenic effect in the test group. ConclusionThe use of CGF combined with iliac cancellous bone and composite bone materials to repair extensive mandibular jaw defects facilitates bone formation and reductions in inflammation in the defect area in the short term, which deserves further research in clinical practice.