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In our previous study, we examined the composition and method of heat treatment were in concordance, hardness increased in as-received materials and decreased in Liquid Rapid Solidification treatment (LRS) alloys. It was suggested then, that the inherently &beta phase in microstructures played a prominent role in the differences observed. In the present study, we re-melted as-received and LRS materials and examined hardness after solution treatment. Additionally, the presence/absence of the &beta phase was investigated. We found that &beta phase educes under slow solidification speeds. Additionally, even after high solution treatment at 1123K, the &beta phase does not solidify.

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High-Cr and high-N contained Co-Cr-Mo alloys were fabricated using conventional dental casting apparatus and thier microstructure and mechanical properties of Co-Cr-Mo alloys were evaluated in this study. Typical dendritic structures were observed in the Co-Cr-Mo alloys. The gamma phase (fcc) was dominant in the alloys. It was found that the high-Cr and high-N contained Co-Cr-Mo alloys showed higher elongation compared to the conventional Co-Cr-Mo dental alloys.

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Gold-based alloys have been used for telescopic dentures with good prognosis so far. However, the drawback of the dentures is their weight owing to the density of the gold-based alloys. Therefore we paid attention to Co-Cr alloys, which has lower density than the gold-based alloys. The retentive force of telescopic denture is influenced by interfacial stress, static frictional force and the taper angle. In this study, static frictional coefficients of a gold-based alloy and a Co-Cr alloy were evaluated and the results obtained were discussed.

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Orthodontic wires made of stainless steel or cobalt-chromium alloy are often brazed with silver solder in orthodontic appliances. Galvanic corrosion between the orthodontic wires and silver solder was examined on the basis of released ions and electrochemical behavior. In the static immersion test in 0.9% NaCl solution, the amounts of ions released from both wires brazed with silver solder tended to increase when the surface area of the silver solder on the wires increased. Especially, this condition obviously increased that of Ni ions, which were rarely released from the non-soldered stainless wires.

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The bulk glassy alloys, which have amorphous structure without any crystal phases, are expected to be novel dental materials because of their extremely high strength and low Young's modulus. We focused the fact that the corrosion resistances of Zr-based bulk glassy alloys were much improved by small addition of Pd/Pt. In this work, the effects of thermal treatment and composition of the passive film on corrosion resistance of Zr-based bulk glassy alloy were investigated. The mechanism of the corrosion resistance improvement was discussed from these results.

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On exposure to the solution containing hydrogen peroxide, tarnish and corrosion of titanium alloys are known to happen occasionally. However, the discoloration and corrosion behaviors of titanium under acidulated or alkaline conditions have not been discussed in detail. In this study, we have discussed about the color, glossiness, surface roughness, and surface morphology of titanium after immersion in acidic and alkaline solutions containing hydrogen peroxide.

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Generally, that the bond-strength of the adhesive system is influenced by the techniques of each operator. The operators, who are the 1st year students of graduate course, have a little knowledge of the adhesive systems. The micro-tensile bond strength testing was performed using current adhesive systems according to manufacturers' instructions. Data was analysed in terms of technique-sensitivity and improving of operators' bond performance.

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The prospect of this study was to propose novel biocompatible polymer-metal complex with an approach for periodontal dressing. The feasibility of complex formation between sodium phosphorylated chitosan (PCTS) and zinc oxide (ZnO) was investigated. Cytotoxicity of the complexes was also evaluated by direct contact test. The PCTS and ZnO complexes with low ZnO ratios exhibited cytocompatibility, whilst commercial periodontal dressing was found to exhibit cytotoxicity to human gingival fibroblast owing to carboxylic available polymeric resins inclusion.

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To effectively exploit the properties of antibacterial agents, we synthesized phosphorylated polysaccharides as the carrier for bactericide delivery. It was indicated that 0.01% phosphorylated pullulan and 0.01% cetylpyridinium chloride (CPC) consistently exhibited an antibacterial effect, even after rinsing with distilled water, although CPC at a concentration of 10% showed no effect on bacterial growth after slight rinsing.

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Considering the safety of the ozone, lecturers consider the method using the low- concentration ozone, and small cold cathode VUV discharge tube ( the 185nm wavelength ) and inverter and ultraviolet lamp of various shapes of argon, mercury are produced experimentally, and manufacturing instrument development of gas ozone, ozone water and ozoned oil of the low concentration is carried out, and it has been reported in this Society. The ozone disinfection utilization electric toothbrush for the dental caries prevention was developed, and as a result of examining this instrument, it was proven that the practical application was possible.

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Recently, many CAD/CAM systems to fabricate ceramic and metallic dental prostheses have been developed. However, in the fabrication of denture, no CAD/CAM system has been seen. We attempt to develop a novel system using VR haptic device CAD tool and acrylic resin layering RP CAM machine. In the present study, we will report on the CAD process of partial and full denture.

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Reinforcing, low temperature degradation (LTD) controlling and bio-activating ability of 1, 3 and 10wt% of hydroxyapatite (HA) including 20wt% alumina-mixed Y2O3-stabilized tetragonal zirconia (Al-YSZ) ceramics were investigated in the aim of developing bio-ceramics with practical strength and bio-activity as the load-bearing biodevices.

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In the present study, effect of firing temperature on properties of yittria stabilized tetragonal zirconia polycrystals was evaluated through the Vickers hardness test, light transmittance, crystal phase changes and biaxial flexural strength.

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With this in vitro study, the bond strength between zirconia frame and veneered porcelain ,being veneered with conventional layering technique or overpressed, with or without ziliner samples were evaluated.

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The importance of the control of biofilm on denture has been widely accepted. The aim of our study was : first to investigate the pretreatment to immobilize oragnosilane quarterly ammonium salts (Si-QAC) on the acrylic surface to minimize the denture plaque formation, and second to examine the antimicrobial activity and the removal ability of biofilm by Si-QAC solution. The results have shown that the pretreatment with ozone water, plasma and electromagnetic wave were most effective to immobilize Si-QAC on acrylics. In addition, Si-QAC solution has shown higher antifungal effects together with the excellent removal ability against Candida biofilm.

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The Colloidal Platinum Nanoparticles (CPN) were recently invented as a functional material. The compositions of CPN are platinum particles which have a diameter of 2 nm, sodium citrate surrounding platinum particles, and water. We found that CPN has the effects to improve the resin/dentin bond strength using 4-META/MMA-TBB significantlly. The aim of this study is to investigate the effects of Colloidal Gold Nanoparticles (CGN) instead of CPN on resin/dentin adhesion.

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In this study, the self-etching primer was prepared by adding the acidic methacryl ester monomer, MEP, MDP or the acidic methacryl amide monomer, NMEP to the hydrophilic methacryl amide monomer, NMGly. The bond strengths of resin to the dentin, conditioned by the experimental primers which were stored for 0, 6 or 14 weeks, were examined, before and after thermo-cycling. As a result, the NMEP-NMGly primer exhibited higher dentin bond durability than the MEP-NMGly and MDP-NMGly primers.

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