الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
A randomized controlled study was performed on 30 male New Zealand White rabbits where mid- diaphyseal segmental ulnar ostectomy was performed leaving a 12mm critical size bone defect to investigate the role of Platelet-Rich Fibrin and Zinc Oxide Nanoparticles on the healing of the ulnar segmental critical size defects. Animals were randomly divided into 3 groups (10 each): Control group, (The defect was left for spontaneous healing without addition of any biomaterial), PRF group (defect filled with PRF clot), and PRF/ZnONPs group (The defect filled with both PRF and ZnONPs). The healing capacity of the CSD between the groups was evaluated by radiographic examination at day zero, 30, 45, 60, 75 and 90 days in addition tocone beam computed tomographic examination at day 30, 60 and 90 postoperatively. Based on radiographic and computed tomographic findings, The controlgroup showed the least percent of defect filling among the experimental groups alongthe study. Spontaneous healing did not occur till the end of the study and theprogress was too slow. Bridging was only unicortical and canalization was notachieved at all. The quality of the small amount of regenerated bone was found to behigh with high bone density. Remodeling has not started in the control group at all. Inthe PRF group, complete bridging and early complete filling of the defect with lowdensity bone was observed along with the formation of an extensive callus andmoderate remodeling.While the PRF/ZnONPs group was superior to the other twogroups with earliest and maximal defect filling, highest bridging and canalizationscores, highest bone density, least amount of callus and maximal radiographic andremodeling score. As a conclusion, a 12 mm segmental ulnar defect in rabbits is a critical bone defect that is notable to heal spontaneously and the PRF is a powerful bioscaffold that accelerated the bone formation in the induced CSD. Also, addition of ZnONPs to PRF potentiates its effect and greatly enhances and accelerates bone formation in the rabbit ulnar CSD and increases bone quality and density.Moreover, The CBCT showed promising results for CSD healing evaluation, particularly for remodeling and canalization.