The bone-regenerative properties of Emdogain adsorbed onto poly(D,L-lactic-coglycolic acid)/calcium phosphate composites in an ectopic and an orthotopic rat model

Background and Objective: The aim of this study was to evaluate the bone-regenerative properties of Emdogain((R)) in osseous and nonosseous sites. Material and Methods: For the orthotopic study, unloaded poly(D,L-lactic-coglycolic acid)/calcium phosphate implants, and poly(D,L-lactic-coglycolic acid)/calcium phosphate implants loaded with different concentrations (0.25, 0.50 or 0.80 mg per implant) of enamel matrix derivative (EMD), were inserted into cranial defects of 24 rats. The implantation time was 4 wk. For the ectopic study, 32 implants were placed subcutaneously. The same study period and groups as in the orthotopic study were used. Methods of evaluation consisted of descriptive histology, histomorphometry and an in vitro EMD-release study. Results: In the orthotopic study, new bone formation was most abundant in unloaded implants followed by 0.50-mg EMD composites. Histomorphometric measurements showed 54 +/- 15.0% bone ingrowth for unloaded implants, 19 +/- 22.5% bone ingrowth for 0.25-mg EMD composites, 40 +/- 23.6% bone ingrowth for 0.50-mg EMD composites and 26 +/- 17.6% bone ingrowth for 0.80-mg EMD composites. Light microscopic analysis of the subcutaneous sections from the ectopic study revealed no bone formation in any group after 4 wk. The in vitro release study showed 60% cumulative EMD release after 4 wk. Conclusion: Emdogain((R)) is not osteoinductive and is not able to enhance bone healing in combination with an osteoconductive material, such as poly(D,L-lactic-coglycolic acid)/calcium phosphate cement.