A combination graft of low-molecular-weight silk fibroin with Choukroun platelet-rich fibrin for rabbit calvarial defect

Objective: The objective of this study was to determine the capabilities of silk fibroin as a biomaterial template for bone formation when mixed with Choukroun platelet-rich fibrin (PRF) in vivo. Study design: Ten New Zealand white rabbits were used for this study and bilateral round shaped defects were formed in the parietal bone (diameter 9.0 mm). The silk fibroin was digested by acid and made into powder (molecular weight <1.0 kDa). The right side (experimental group) received the silk fibroin plus platelet-rich fibroin and the left side (control group) did not receive a graft. Animals were killed at 6 weeks and 12 weeks. The specimens were examined by microscopic computerized tomography (μ-CT). Subsequently, they underwent decalcification and were stained for histologic analysis. Results: There was no significant difference between groups at 6 weeks after operation. In the μ-CT results, however, tissue mineral content in the experimental group at 12 weeks after operation was 132.09 ± 4.41 and that in the control group was 126.42 ± 6.62 (P = .011). Tissue mineral density in the experimental group was 2,088.88 ± 648.34, and that in the control group was 2,029.72 ± 668.22 (P = .013). The results of the histomorphometric analysis were in accordance with the μ-CT results. The total new bone was 49.86 ± 7.49% in the control group at 12 weeks after the operation and 59.83 ± 10.92% in the experimental group (P = .021). Conclusion: A combined application of Choukroun PRF with acid-digested silk fibroin showed more rapid bone healing than unfilled control.