Effect of bone morphogenetic protein-2, demineralized bone matrix and systemic parathyroid hormone (1-34) on local bone formation in a rat calvaria critical-size defect model

Aim To determine the potential of recombinant human bone morphogenetic protein‐2 (rhBMP‐2) soak‐loaded on to an absorbable collagen sponge (ACS) to induce local bone formation compared with the clinical reference demineralized bone matrix (DBM) and to investigate potential additive/synergistic effects of exogenous parathyroid hormone (PTH). Methods Critical‐size (8 mm), through‐through calvaria osteotomy defects in 160 adult male Sprague–Dawley rats were randomized to receive one of eight interventions: rhBMP‐2/ACS, DBM, ACS, or serve as controls (empty defects) combined or not with systemic PTH. Ten animals from each group were followed for 4 and 8 wks for radiographic and histometric analysis. Multivariable analysis was used to assess the effect of experimental intervention and healing time on local bone formation. Results In the multivariable analysis, rhBMP‐2/ACS exhibited significantly greater histologic bone formation than control (β ± SE: 54.76 ± 5.85, p