BMP-2: biological challenges to its clinical use.

Protein therapy using osteogenic factors is an exciting technique for bone regeneration and implant placement. BMPs are known to stimulate bone formation in ectopic sites; BMP-2 is the most commonly used. In 2007, the FDA approved BMP-2 delivered with an absorbable collagen sponge (ACS) carrier for clinical use in craniofacial deformities. Almost all the publications on BMP-2 showed relatively significant results in augmenting bone at the site of implantation for a period of up to 16 weeks; however, the long-term clinical outcome of BMP-2 application is lacking and yet to be proven reproducible. Many biological obstacles prevent the maintenance and prolonged existence of high bone volume initially formed, thus compromising the long-term implant survival. In this paper, we review these obstacles and highlight their importance in the oral environment. We underscore the ambiguity that has emerged about the safety of BMP-2 in clinical application. Since biology dictates success, we believe at present that any protein therapy for bone regeneration is likely to be ineffective over a long period of time.