Histomorphometric Analysis of Differential Regional Bone Regeneration Induced by Distinct Doped Membranes

Our objective is to evaluate the regional regenerative potential of calvarial bone in critical- sized defects in a rabbit model using novel nanostructured silica-loaded membranes doped with zinc or doxycycline. Nanostructured membranes of (MMA)1-co-(HEMA)1/(MA)3-co-(HEA)2 loaded with 5 wt% of SiO2 nanoparticles (HOOC-Si-Membranes) were doped with zinc (Zn-HOOC-Si- Membrane) or doxycycline (Dox-HOOC-Si-Membrane). Critical bone defects were created on six New-Zealand-breed rabbit skulls and covered with the membranes. A sham defect without a membrane was used as the control. After six weeks, a histological analysis (toluidine blue technique) was employed to determine the area percentages of newly formed bone, osteoid bone, and soft tissue. The measurements were performed by dividing the total defect area into top (close to the membrane) and bottom (close to the dura mater) regions, or peripheral (adjacent to the old bone) and central (the sum of the remaining zones) regions. The peripheral regions of the defects showed higher osteogenic capacity than the central areas when the membranes were present. The proportion of new bone adjacent to the dura was similar to that adjacent to the membrane only when the HOOC-Si-Membranes and Zn-HOOC-Si-Membranes were used, indicating a direct osteoinductive effect of the membranes.