Bone morphogenetic protein-2 loaded poly(D,L-lactide-co-glycolide) microspheres enhance osteogenic potential of gelatin/hydroxyapatite/β-tricalcium phosphate cryogel composite for alveolar ridge augmentation.

BACKGROUND/PURPOSE: Sufficient bony support is essential to ensure the success of dental implant osseointegration. However, the reconstruction of vertical ridge deficiencies is still a major challenge for dental implants. This study introduced a novel treatment strategy by infusing poly(D,L-lactide-co-glycolide) (PLGA) microspheres encapsulating bone morphogenetic protein-2 (BMP-2) within a gelatin/hydroxyapatite/β-tricalcium phosphate (gelatin/HA/β-TCP) cryogel composite to facilitate supra-alveolar ridge augmentation.

METHODS: The gelatin scaffold was crosslinked using cryogel technique, and HA/β-TCP particles were mechanically entrapped to form the gelatin/HA/β-TCP composite. Co-axial electrohydrodynamic atomization technology was used to fabricate PLGA microspheres encapsulating BMP-2. The composites of gelatin/HA/β-TCP alone, with infusion of BMP-2 solution (BMPi) or microspheres (BMPm), were fixed on rat mandibles using a titanium mini-implant for 4 weeks, and the therapeutic efficiency was evaluated by micro-computed tomography, bone fluorochrome, and histology.

RESULTS: The gelatin/HA/β-TCP composite was homogenously porous, and BMP-2 was sustained release from the microspheres without initial burst release. Ridge augmentation was noted in all specimens treated with the gelatin/HA/β-TCP composite, and greater bone deposition ratio were noted in Groups BMPi and BMPm. Compared with Group BMPi, specimens in Group BMPm showed significantly greater early osteogenesis and evident osseointegration in the supra-alveolar level.

CONCLUSION: BMP-2 loaded PLGA microspheres effectively promoted osteogenic potential of the gelatin/HA/β-TCP composite and facilitated supra-alveolar ridge augmentation in vivo.