Effect of recombinant human fibroblast growth factor‐2 on bone formation in rabbit mandibular distraction models using β‐tricalcium phosphate

This study was designed to evaluate the effect of recombinant human fibroblast growth factor‐2 (rhFGF‐2) on the amount and period of new bone formation in rabbit mandibular distraction models using β‐tricalcium phosphate (β‐TCP) as a bone graft substitute. Sixteen male Japanese White rabbits were divided into the following four experimental groups: 1, distraction alone; 2, distraction with β‐TCP granules; 3, distraction with rhFGF‐2 (25 µg/50 µL) injected into β‐TCP granules; and 4, distraction with rhFGF‐2 (100 µg/50 µL) injected into β‐TCP granules. The bones were harvested at 4 weeks after the operation and examined using soft radiography, micro‐computed tomography (micro‐CT), and peripheral quantitative computed tomography (pQCT). The dissected mandibles were stained using the Villanueva bone staining method, and the amount of new bone formed, bioresorption of β‐TCP, and new blood vessel formation were morphometrically calculated using bone histomorphometry. Radiopaque areas were observed more frequently in the distracted area of groups 3 and 4. Micro‐CT analysis revealed partial new bone formation in the central region of the distracted area in groups 3 and 4. pQCT analysis revealed increased bone mineral density in groups 3 and 4. Histomorphometric analysis revealed increased newly formed bone and blood vessel areas in groups 3 and 4. In group 4, the number of osteoclasts around the β‐TCP granules had significantly increased. The present findings suggested that the combined use of rhFGF‐2 and β‐TCP reduced the treatment period for distraction osteogenesis and accelerated the formation of a new high‐quality bone.