Bone substitutes used for three-dimensional augmentation

The study assessed the use of a new xenograft material. The aim of the present in vivo experiment was to obtain information on the clinical results and the rate of bone formation using two new experimental bone substitutes compared with an established bovine bone substitute and the autogenous graft, which is considered the gold standard for grafting. In the study miniature pigs were used as an animal model as they represent the highest similarities to human bone regarding anatomy, morphology and remodelling and as a species are considered to be a close representation of human bone considering the process of bone formation. In a surgical procedure the second premolars of 20 animals were extracted in all 4 quadrants and defects created which were filled with the different materials. After 30 days the first group was sacrificed and the second group after 60 days. To evaluate the rate of new bone formation sections were ground down for toluidine blue staining. Furthermore, the technique of fluorochrome sequential labelling was used to obtain information about the dynamics of new bone formation and remodelling processes in the loaded area at different times. A greater part of the defects loaded with the experimental blocks could not be integrated in the statistical analysis because the animals either lost the grafts a few weeks after transplantation or the healing was unsuccesssful. Histological examination revealed about 50% lower evidence of bone induction of the experimental blocks compared to the bovine reference material. Fluorescence microscopy did not offer any significant differences between the bone biopsies. The results of this study demonstrate that the use of the experimental blocks was less successful considering healing and amount of new bone formation compared to the established bovine bone substitutes grafts. Nevertheless, the study showed that the combination of fluorescence polarization and histological analysis is an efficient method to obtain information about bone remodelling and fibrous reactions on top of the basal bone by bone grafting experiments.