Mandibular reconstruction using a calcium phosphate/polyethylene glycol hydrogel carrier with BMP-2

Aim: To test the hypothesis that a synthetic hydroxyapatite/beta-tricalcium phosphate (HA/TCP) construct combined with polyethylene glycol (PEG) hydrogel including recombinant human bone morphogenetic proteins-2 (rhBMP-2) enhances new bone formation compared with bone morphogenetic proteins-2 (BMP-2) delivered using the HA/TCP construct alone. Material and Methods: Bilateral mandibular partial thickness 20 x 8 x 8 mm (L x W x H) alveolar defects were surgically created in the edentulated posterior mandible in 18 female minipigs. Randomized into two groups of nine animals each, the alveolar defects either received HA/TCP or HA/TCP/PEG with or without BMP-2 (105 mu g/defect) in contra-lateral sites using a split-mouth design. Primary outcome, bone density (%) within four regions of interest, was evaluated following a 4-week healing interval when the animals were killed for histometric analysis. Results: Bone morphogenetic proteins-2 loaded onto HA/TCP constructs significantly enhanced new bone formation compared with HA/TCP controls. Adding PEG apparently obstructed BMP-2 induced bone formation. Conclusion: Polyethylene glycol compromises the osteogenic effect of BMP-2.