الفهرس 
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Abstract
The purpose of this study was to evaluate the effect of silk fibroin in the regeneration of bone in sockets of rabbits. Silk fibroin has the potential to play an important role in tissue engineering, thus can be tailored to regenerate bone in sockets after teeth extraction avoiding alveolar bone loss. It has proven that it has a role in recruitment of osteogenic cells and has angiogenic potential. The results were assessed using histological, scanning electron microscopic examination, histomorphometric analysis and Energy Dispersed Spectroscope Microanalysis [EDXA]. 36 adult male New Zealand white rabbits were divided blindly into 3 groups with12 rabbits in each group: Control group: the sockets were left without a graft, Collagen group: the sockets were filled with a collagen sponge, Silk group: the sockets were filled with a silk sponge. 6 animals from each group were sacrificed after the procedure at two intervals (2 and 6 weeks). The mandibles were dissected out and the right halves were separated to be prepared and separated into two halves. The mesial half was used for histological and histomorphometric analysis, while the distal half was used for scanning electron microscopic examination and EDXA.The characterization of the silk scaffold revealed interconnected pores with varying pore diameters, the micropores ranged from 30-60 μm while the macropores ranged from 90-400 μm. the pores were randomly arranged and had dense pore walls. Histological findings revealed that silk fibroin resulted in bone regeneration that was denser and more mature than that of the control and collagen group, at both experimental intervals. The collagen groups showed improved bone formation than the control group. Both the collagen and silk group showed enhanced blood supply. These results were quantitatively confirmed by the histomorphometric analysis that revealed that the highest
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mean of newly formed bone was in the sockets grafted with silk, followed by collagen grafts and the least was scored by the control group; this finding was consistent for both intervals of the experiment. SEM examination demonstrated the same results, with sockets of the control group with least bone formed, while the collagen and silk group showed higher bone density and maturation of the bone at the end of experimental period. The EDXA confirmed the same results were the collagen and silk group had higher levels of calcium and the calcium phosphate ratio was closer to the normal values of native bone, while the control group failed to increase the calcium levels throughout the experiment.