Real-time assessment of guided bone regeneration in critical size mandibular bone defects in rats using collagen membranes with adjunct fibroblast growth factor-2

Background/purpose: Fibroblast growth factor-2 (FGF-2) regulates bone formation. The concept of guided bone regeneration using a resorbable collagen membrane (RCM) is generally accepted in implant dentistry. This study aimed to investigate the bone healing pattern in rat mandibular bone defects in real-time with and without RCM containing FGF-2 (RCM/FGF-2). Materials and methods: Critical-size circular bone defects (4.0 mm diameter) were created on both sides of the rat mandibular bone. The defects were randomly divided into the following groups: control, RCM alone, RCM containing low (0.5 μg) or high (2.0 μg) concentration of FGF-2. We performed real-time in vivo micro-computerized tomography scans at the baseline and at 2, 4, and 6 weeks, and measured the volume of newly formed bone (NFB), bone mineral density (BMD) of NFB, and the closure percentage of the NFB area. At 6 weeks, the mandibular specimens were assessed histologically and histomorphometrically to evaluate the area of new bone regeneration. Results: Real-time assessment revealed a significant increase in the volume, BMD, and closure percentage of the NFB area in the RCM/FGF-2-treated groups than that in the control and RCM groups. In the H-FGF-2 group, the volume and BMD of NFB exhibited a significant increase at 6 weeks than that at the baseline. Histological evaluation revealed the presence of osteoblasts, osteocytes, and blood vessels within the NFB. Conclusion: The real-time in vivo experiment demonstrated that RCM/FGF-2 effectively promoted bone regeneration within the critical-size mandibular defects in rats and verified new bone formation starting in the early postoperative phase.