Comparison of silkworm-cocoon-derived silk membranes of two different thicknesses for guided bone regeneration

The objective of this study was to compare the effectiveness of silk membranes (SMs) of different thicknesses for guided bone regeneration. Two kinds of SMs were prepared (SM1: 0.01 mm thickness, SM2: 0.5 mm thickness). Before use in animal experiments, scanning electron microscope images were taken to examine the gross morphology of each membrane. Ten New Zealand white rabbits were used for this study. Bilateral round-shaped defects were created in the parietal bone (diameter: 8.0 mm) and each defect was covered with SM1 or SM2. Animals were killed at 4 weeks and 8 weeks. Bone regeneration was analyzed in each specimen by micro-computed tomography (μ-CT) and histological analysis. In the μ-CT analysis, the average amount of newly formed bone in the SM2 group was greater than that in the SM1 group. There was a significant difference at 4 weeks after surgery (P = 0.004). In the histological analysis, the amount of formed lamellar bone was much greater in the SM2 group than in the SM1 group at 8 weeks after surgery (P = 0.021). In conclusion, the thick SM was much more effective for bone regeneration of bone defects than the thin SM.