New approach for vertical bone regeneration using in situ gelling and sustained BMP‐2 releasing poly(phosphazene) hydrogel system on peri‐implant site with critical defect in a canine model

Abstract An injectable hydrogel system with sustained bone morphogenetic protein 2 (BMP‐2) release ability was developed for vertical bone regeneration at peri‐implant sites and enhanced osseointegration of dental implants. In three young male beagle dogs, a pair of defects was created on both sides of the mandibular bone. Next, two implants were transplanted into each defect. In situ gelling polymer solutions with or without BMP‐2 were applied to cover the implants and mandibular defects. The effects of the in situ gelling and sustained BMP‐2 releasing (IGSR) hydrogel system on peri‐implant bone regeneration were evaluated by radiologic examination, micro‐computed tomography, and histomorphometric analysis. Twelve weeks after the treatment, significant bone generation at the peri‐implant site occurred following BMP‐2/IGSR hydrogel treatment. Bone volume and mineral density were increased by 1.7‐ and 1.3‐fold, respectively ( p < 0.01 and 0.05 vs. control, respectively) for the BMP‐2/IGSR hydrogel system. And, 0.57–0.31 mm vertical bone generation was observed at the peri‐implant site for the BMP‐2/IGSR hydrogel system, while rare vertical bone generation occurred in the control group. The BMP‐2/IGSR hydrogel system significantly increased bone to implant contact % between induced bone and existing bone ( p < 0.05 and 0.01 vs. control). These vertical bone regeneration and higher osseointegration levels demonstrated the effectiveness of the BMP‐2/IGSR hydrogel system. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 751–759, 2018.