Tissue Dynamics of Native Collagen Membranes for Guided Bone Regeneration

Objectives: The aim of the present study was to evaluate the early cellular and structural pattern of bone healing following GBR, using a novel native collagen membrane.
Methods: Defects were created in the trabecular region of rat femurs, filled with deproteinized bovine bone (DBB) and covered with either a native collagen membrane (creos xenoprotect^TM, Nobelbiocare, Zurich, Switzerland) or a collagen membrane (Bio-Gide^®, Geistlich, Wolhusen, Switzerland) or left empty (sham). Defects were harvested after 3 and 21 days for histology/histomorphometry and gene expression analysis. Histomorphometric analysis was performed of the total defect area (ROI I) and the center portion of the defect (ROI II). For statistics Kruskal-Wallis and Mann-Whitney Tests were used.
Results: The analysis revealed no statistical difference at 3d. At ROI I. No statistically significant differences in new bone formation at 21 days. However, when evaluating ROI II, a significantly higher total bone formation was seen for the test membrane compared (20%) to the control membrane (9.2%) (p < 0.050). Differences between the two membranes were most pronounced when analyzing de novo bone formation in the intergranular space of ROI II (34.9% and 15.5 % for test and control membrane, respectively) (p< 0.017).
Conclusions: These results provide histomorphometric evidence that different collagen membranes contribute differently to the GBR healing process. In the control membrane, de novo bone formation was primarily localized to the peripheral part of the defect. By contrast, the test membrane demonstrated significantly higher amount of bone in the central portion of the defect. This suggests that the test membrane may have a different and more active role where the tissue dynamics are regulated not only close to the membrane barrier but also in the center portion of the defect. The findings will be further characterized by gene expression analysis.