The purpose of this study was to compare the effects of different densities of biodegradable hydroxyapatite fiber (HAf) material on vertical bone augmentation. Ten male Japanese white rabbits were used. Polytetrafluoroethylene chambers, which were filled with different HAf densities(termed 'low', 'intermediate', 'high' or 'empty'), were fixed to the calvarial bone. After 12weeks, animals were euthanized. Specimens were radiologically analyzed with micro-computed tomography and histologically examined. In the intermediate-density group the new bone volume was the highest. The present results suggest the potentiality of this material as bone substitute and the importance of material density in its application.

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The objective of this study was to assess the effects of vertical bone augmentation using a novel bone substitute. Porous composite uncalcined hydroxyapatite (u-HA; 70 wt%) and poly-DL-lactide (PDLLA; 30 wt%) blocks were grafted onto the cranial bone of 18 rabbits. Animals were sacrificed 1, 3, and 6 months after implantation. The molecular weight of PDLLA was measured and histological and histomorphometrical analyses were performed to evaluate new bone formation and material degradation. The molecular weight of PDLLA decreased significantly at each time-point. The blocks directly contacted with the original bone. New bone formation was observed whereas the block was gradually absorbed. Significantly more bone had been formed at 3 and 6 months than at 1 month. Similarly, bone height at 3 and 6 months was significantly greater than that at 1 month. The present study demonstrates that the u-HA/PDLLA block is biodegradable and osteogenic, suggesting that this material is a useful material for vertical bone augmentation.

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Ozone nano bubble water (NBW3) seems to be suitable as an adjunct treatment to oral infectious diseases as for antimicrobial effects and compatibility with oral tissues to overcome disadvantage of conventional mouth rinses.The aim of this study was to determine the effect of NBW3 on sterilization and cytotoxicity. We analyzed the bactericidal effect of NBW3 against oral infectious bacteria. Cytotoxic ability was estimated using human gingival fibroblast cells stained with PI/Calcein-AM and fluorescence microscopy. The reduction in the number of bacteria in the NBW3 group was significantly greater than those in the CHX group and similar to that of Listerine^® against P. gingivalis. Cytofluorometric assays revealed higher biocompatibility of NBW3 against fibroblasts.NBW3 had significantly bactericidal activity against oral infectious bacteria and biocompatible with mammalian cells compared with conventional mouth rinses. The oral application of NBW3 might have potential as an adjunctive treatment for oral infectious diseases.

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Bone is one of the most important oral tissues. Osteoclasts play important roles in bone tissue engineering. Previously, we profiled microRNA (miRNA) expression during osteoclastogenesis using microarrays. miRNAs are small, noncoding RNAs that are involved in various biological processes, including cellular differentiation, proliferation, apoptosis, and organ development. Recently, the presence of miRNAs in extracellular microvesicles was reported. It is not known whether osteoclasts secrete extracellular microvesicles containing miRNAs. We investigated miRNA expression in extracellular microvesicles in conditioned medium of cultured osteoclasts using RT-PCR. Specifically, we investigated eight miRNAs deemed important for osteoclastogenesis in our previous study: let-7e, miR-21, miR-33, miR-155, miR-210, miR-223, miR-378, and miR-1224. Of these, the expression levels of miR-378, miR-210, and miR-21 were very high, while no significant miR-33 or miR-1224 expression was detected. These results suggest that osteoclasts secrete extracellular microvesicles containing specific miRNAs, but that they do not contain the entire set of intracellular miRNAs.

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Polyethyl methacrylate methacryloyloxyethyl methyl succinate/dimethacrylate 1,6 hexanediol (PEMA-TSA/HX) resin has been developed to solve biological problems caused by methacrylate resins, which are commonly used in dentistry and medicine. We previously reported its physical and mechanical properties in detail. The purpose of this study was to examine the biocompatibility of PEMA-TSA/HX resin.Biocompatibility of the resin towards fibroblast-like and osteoblast-like cells was evaluated according to the methods in ISO 10993-5 and a subcutaneous implantation test (ISO 10993-6) was carried out. The PEMA-TSA/HX resin showed favorable biological affinity, both in vitro and in vivo, compared with Osteobond^®, which is a current implantable resin material commonly used in orthopedic surgery. It is therefore considered to have many potential clinical applications.

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This study examined titanium onto which bioactive factors were adsorbed, with the objective of developing a scaffold with many pores that could be expected to promote cell infiltration. Titanium powder was mixed with ammonium hydrogen carbonate as a binder in a 5:5 ratio by weight, and a method based on the powder metallurgy method was used to construct a prototype scaffold. Bone morphogenetic protein (BMP) was adsorbed onto the prototype scaffold, and its osteoinductive potential was evaluated. The results showed that the prototype scaffold possessed pores capable of infiltration by cells, and that sufficient osteoinduction was possible without suppressing the activity of BMP.

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We prepared highly porous beta-tricalcium phosphate (β-TCP) scaffolds with different open-cell structure sizes. The aim of this study was to examine whether the open-cell size of the scaffold affected osteoinduction in combination with fibroblast growth factor-2 (FGF2) in rats. Polyurethane foam was immersed in β-TCP slurry and sintered in a furnace. Porous β-TCP scaffolds were prepared in three cell sizes (0.6, 0.4 and 0.3 mm) and characterized. Subsequently, each scaffold with FGF2 was implanted to rat cranial bone. Histomorphometric analyses were taken at 35 days post-surgery. The results showed that each β-TCP scaffold exhibited fully interconnected porosity, and frequently allowed bone tissue ingrowth. The 0.4-mm cell sized scaffold significantly promoted bone augmentation compared to the 0.3-mm type. Resorption of the β-TCP scaffold of 0.4-mm cell size was frequently accelerated. In conclusion, FGF2-loaded β-TCP scaffolds with 0.4-mm cell size would be effective for bone tissue engineering.

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