Objective To determine if locally administered bone morphogenetic protein-2（BMP-2） and osteoprotegerin（OPG） improved osteogenesis and new bone formation by trans-sutural distraction osteogenesis. Methods Twenty four dogs were divided into three groups randomly and received new internal trans-sutural distraction osteogenesis treatment. Five days after operation, infusion apparatus with double-tube was inserted to submucosa near the distracted zone
to deliver controlled release agent of recombinant human bone morphogenetic protein-2/poly（lactic-co-glycolic acid）/fibrin sealant（rhBMP-2/PLGA/FS） in group A and group C. Recombinant human osteoprotegerin/fibrin sealant（rhOPG/FS） was injected three weeks later in group B and group C. Histology staining and bone histomorphometry were used to measure the changes of maxillary bone sutura after distraction for 1, 2, 4 and 6 weeks. Results New bone formation
observed in distracted zone showed a significant increase in group A and C. Transmission electron microscope showed the osteoblast and osteocyte were active with dilated rough endoplasmic reticulum and a large number of chondriosomes and Golgi complex. After distraction for 6 weeks, indexes of osteoblast of group A, B, and C were 38.5±7.7, 35.7±6.5, and 41.7±11.0, indexes of osteoclast（Ioc） were 5.9±1.0, 1.2±0.3, and 2.8±0.4, bone trabecula thicknesses were （38.36±13.28）,（66.20±9.16）, and（51.85±9.92）μm respectively. Increased bone density and decreased Ioc were found in group B and C. Conclusion The new elastic distractor is effective in inducing new bone formation. BMP-2 and OPG combination acts synergistically, and leads to significant enhancement of bone formation and remodeling.
