Evaluation of Implants Coated With Recombinant Human Bone Morphogenetic Protein-2 and Vacuum-Dried Using the Critical-Size Supraalveolar Pen-Implant Defect Model in Dogs

Background: Endosseous implants coated with recombinant human bone morphogenetic protein-2 (rhBMP-2) in a laboratory bench setting and air-dried induce relevant bone formation but also resident bone remodeling. Thus, the objective of this study is to evaluate the effect of implants fully or partially coated with rhBMP-2 and vacuum-dried using an industrial process on local bone formation and resident bone remodeling. Methods: Twelve male adult Hound Labrador mongrel dogs were used. Critical-size, supraalveolar, peri-implant defects received titanium porous oxide surface implants coated in their most corona I aspect with rhBMP-2 (coronal-load, six animals), or by immersion of the entire implant in a rhBMP-2 solution (soak-load, six animals) for a total of 30 mu g rhBMP-2 per implant. All implants were vacuum-dried. The animals were sacrificed at 8 weeks for histometric evaluation. Results: Clinical healing was unremarkable. Bone formation was not significantly affected by the rhBMP-2 application protocol. New bone height and area averaged (+/- SE) 3.2 +/- 0.5 versus 3.6 +/- 0.3 mm, and 2.3 +/- 0.5 versus 2.6 +/- 0.8 mm(2) for coronal-load and soak-load implants, respectively (P>0.05). The corresponding bone density and bone implant contact registrations averaged 46.7% +/- 5.8% versus 31.6% +/- 4.4%, and 28% +/- 5.6% versus 36.9% +/- 3.4% (P>0.05). In contrast, resident bone remodeling was significantly influenced by the rhBMP-2 application protocol. Pen-implant bone density averaged 72.2% +/- 2.1% for coronal-load versus 60.6% +/- 4.7% for soak-load implants (P<0.05); the corresponding bone implant contact averaged 70.7% +/- 6.1% versus 47.2% +/- 6.0% (P<0.05). Conclusions: Local application of rhBMP-2 and vacuum-drying using industrial process seems to be a viable technology to manufacture implants that support local bone formation and osseointegration. Coronal-load implants obviate resident bone remodeling without compromising local bone formation. J Periodontol 2010;81:1839-1849.