Introduction The clinical use of bioactive materials for bone augmentation has remained a challenge because of predictability and effectiveness concerns, as well as increased costs. The purpose of this study was to analyse the ability to integrate bone substitutes by evaluating the immunohistochemical expression of the platelet endothelial cell adhesion molecules, vascular endothelial growth factor, collagen IV, laminin, and osteonectin, in the vicinity of bone grafts, enabling tissue revascularization and appearance of bone lamellae. There is a lack of in vivo studies of inflammatory-driven angiogenesis in bone engineering using various grafts. Methods The study was performed in animal experimental model on the standardized monocortical defects in the tibia of 20 New Zealand rabbits. The defects were augmented with three types of bone substituents. The used bone substituents were beta-tricalcium phosphate, bovine hydroxyapatite, and bioactive glasses. After a period of 6 months, bone fragments were harvested for histopathologic examination. Endothelial cell analysis was done by analysing vascularization with PECAM/CD31 and VEGF and fibrosis with collagen IV, laminin, and osteonectin stains. Statistical analysis was realized by descriptive analysis which was completed with the kurtosis and skewness as well as the Kruskal-Wallis and Mann-Whitney statistical tests. Results The discoveries show that the amount of bone that is formed around beta-tricalcium phosphate and bovine hydroxyapatite is clearly superior to the bioactive glasses. Both the lumen diameter and the number of vessels were slightly increased in favor of beta-tricalcium phosphate. Conclusion We can conclude that bone substitutes as bovine bone and beta-tricalcium phosphate have significant increased angiogenesis (and subsequent improved osteogenesis) compared to the bioactive glass. In our study, significant angiogenesis is linked with a greater tissue formation, indicating that in bone engineering with the allografts we used, inflammation has more benefic effects, the catabolic action being exceeded by the tissue formation.

Bone regeneration techniques cannot be done without barrier membranes, even if horizontal or vertical ridge augmentation and socket ridge preservation is taken into consideration. This study presents a comparison between outcomes of bone regeneration, after producing standardized bone defects followed by covering them with membranes, on an animal experimental model. The study was conducted on 18 New Zeeland rabbits, by creating 2 defects in the left tibial bone of each rabbit: one standardized defect with a diameter of 4 mm, and the second by creating 5 monocortical holes with a small round bur. The defects were augmented with bovine bone, beta-tricalcium phosphate and perioglass and they were covered with 3 types of membrane: collagen (12 defects -group A), PTFE membrane (12 defects -group B) and PRF membrane, made from the blood of the same rabbit (12 defects -group C). The animals were sacrificed after 6 months and analysed histomorphometrically. The new bone around graft particles has a thickness of 98.26 μm for collagen membrane, 49.19 μm for PTFE membrane and 63.98 μm for PRF membrane. The density of osteoblasts and osteocytes has an average of 0.0012 for collagen membrane, 0.0009 for PTFE membrane and 0.0010 for PRF membrane. Regarding the collagen membrane, it is observed that when used the bone regeneration appears to have a higher density of osteoforming cells and a higher quantity of new bone

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