Combined use of micro computed tomography and histology to evaluate the regenerative capacity of bone grafting materials

Pre-clinical animal models are commonly used to evaluate the osteogenic potential of bone grafting materials in-vivo. Based on the histology analysis, the currently commercially available bone grafting materials show comparable results with respect to biocompatibility, incorporation and remodeling. In the present pilot study we introduce a methodology to compare calcium phosphate-based bone grafting materials from world-leading companies in clinical trials and analyze them by means of established histology and synchrotron radiation-based micro computed tomography (SR mu CT). The results indicate that the morphology of the bony structures depends on the selected bone grafting material and that an arbitrarily selected histological slice can lead to misleading conclusions. Complementary mu CT data can become the basis for the identification of a representative slice. The registration of the selected histological slice with its counterpart in the three-dimensional mu CT dataset was performed both visually and automatically with well comparable results. This registration allows for the compilation of a joint histogram to identify anatomical features, which can neither be extracted from histology nor from mu CT data on their own. Accordingly, mu CT will become an integral part of studies on the efficacy of bone augmentation materials and beyond.