Comparison of different concentrations of tetracycline-loaded silk fibroin membranes on the guided bone regeneration in the rat calvarial defect model

The objective of this study was to evaluate bone regeneration ability using different concentrations of tetracycline (TC) loaded into silk fibroin membranes (SFMs). Prior to animal experiments, MTT assays and alkaline phosphatase (ALP) assays were performed to evaluate the cellular response of each membrane. Critical sized bone defects (8-mm diameter) on rat calvaria were prepared and covered with SFM containing different concentrations of TC:1% TC (TC1), 5% TC (TC5), 10% TC (TC10), and 0% TC (SFM only). The bone regeneration was evaluated by micro-computerized tomography (μ-CT) and histomorphometric analysis at 4 weeks postoperatively. ALP activity was increased in a dose-dependent manner as the applied TC concentrations. By μ-CT analysis, newly formed bone volume in the TC5 group was significantly higher than that in the SFM only group (P<0.001), the TC1 group (P=0.004), and the TC10 group (P=0.012). From histomorphometric analysis, new bone formation was greater in the TC5 group than in the SFM only group (P=0.003) and the TC1 group (P=0.010). There was no significant difference between the TC5 and TC10 group (P>0.05). In conclusion, TC-loaded SFM showed more bone formation than SFM without TC, and the amount of new bone formation was dependent on TC concentrations.