Evaluation of recombinant human osteogenic protein-1 (rhOP-1) placed with dental implants in fresh extraction sites

This study used the canine mandibular model to evaluate the efficacy of recombinant human osteogenic protein-1 (rhOP-1) for accelerating the healing of fresh dental extraction defects and in encouraging osseointegration of dental implants. Eight implants, four hydroxylapatite (HA)-coated and four non-coated, were placed in each mandible of four adult male mongrel dogs immediately after extraction of the eight premolars. The rhOP-1 was placed in all extraction sites with and without implants on the left side of the mandible. All animals were killed at 12 weeks postoperatively; histologic analysis was performed, including measurement of the new bone formation within the extraction defects, implant incorporation, and implant-bone interface characteristics, including percent bone and fibrous tissue apposition. Extraction sites treated with rhOP-1 were completely filled with new bone and were well incorporated with the host bone at 12 weeks post-operative. New bone had filled the untreated defect sites; however, the amount, density, and degree of remodeling were less than was observed in rhOP-1 sites. Small increases in osseointegration and adjacent new bone formation were apparent surrounding implants placed with rhOP-1. However, good initial implant fit and the small amount of rhOP-1 delivered to the site in this model may have mitigated any large differences. The results of this study demonstrate that new bone formation can be induced around and adjacent to a dental implant placed in a fresh extraction site with a recombinantly produced bone inductive protein.