We evaluated the effects on bone formation of combining synthesized collagen model polypeptides consisting of a Pro-Hyp-Gly [poly(PHG)] sequence and alpha-tricalcium phosphate (-TCP) particles with various median sizes (large: 580.8 µm; small: 136.2 µm; or large and small mixed: 499.3 µm) in a skull defect model in mini-pigs. Quantitative image analyses for the volume density (VD) of new bone revealed that the VD in each -TCP group was significantly higher than that in the poly(PHG) control group, with the mixed group showing the highest VD among all the groups at 4 weeks after implantation. Histological assessments revealed that the small -TCP particles were almost completely degraded at 8 weeks. At 12 weeks, all sizes of -TCP particles were completely degraded and remodeling of the lamellar bone was observed. The present findings suggest that particle size may influence the success of bone formation in defects.
Tobacco smoke is a complex mixture of numerous components. Nevertheless, most experiments have examined the effects of individual chemicals in tobacco smoke. The comprehensive effects of components on tooth movement and bone resorption remain unexplored. Here, we have shown that a comprehensive mixture of tobacco smoke components (TSCs) attenuated bone resorption through osteoclastogenesis inhibition, thereby retarding experimental tooth movement in a rat model. An elastic power chain (PC) inserted between the first and second maxillary molars robustly yielded experimental tooth movement within 10 days. TSC administration effectively retarded tooth movement since day 4. Histological evaluation disclosed that tooth movement induced bone resorption at two sites: in the bone marrow and the peripheral bone near the root. TSC administration significantly reduced the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclastic cells in the bone marrow cavity of the PC-treated dentition. An in vitro study indicated that the inhibitory effects of TSCs on osteoclastogenesis seemed directed more toward preosteoclasts than osteoblasts. These results indicate that the comprehensive mixture of TSCs might be a useful tool for detailed verification of the adverse effects of tobacco smoke, possibly contributing to the development of reliable treatments in various fields associated with bone resorption.
Local IFN-γ administration promoted bone formation in autogenous bone grafts possibly via regulating osteoclastogenesis and TNF-α expression. The data provide insights into the potential roles of IFN-γ in autogenous bone grafting.
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