Adhesive strength between titaniumand various kinds of commercial polymers was evaluated. Among them, poly (ethylene-co-vinyl alcohol) (EVA) showed the highest strength, which might be due to its high hydrophilicity and relatively low melting point. Hydroxyl groups in EVA could be easily converted into carboxyl groups by ozone exposure and the amount of type-I collagen immobilization onto the surface of EVA varies with that of carboxyl groups. These findings might make it possible to culture the periodontal ligament cells on the surface of artificial titanium dental roots, leading to a regeneration of a periodontal ligament.

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The low viscosity fluorinated monomer, FHDDMA, was synthesized and used as a component of composite resin to improve the translucency and hydrolytic stability of photo cured composite resin. The refractive index of FHDDMA was smaller than that of TEGDMA and UDMA, and that of a mixture of FHDDMA and UDMA was close to that of silica filler. The contact angle of water on the FHDDMA polymer was higher than that on the TEGDMA and the UDMA polymers. The polymerization reactivity, translucency, depth of cure, and water sorption of the FHDDMA composite resin were superior to those of the TEGDMA resin. The friction coefficient of the FHDDMA composite resin was less than that of the TEGDMA resin. After undergoing the boiling water-immersion tests, the decrease of knoop hardness of the FHDDMA composite resin was less than that of the TEGDMA resin, and the bending strengths of the FHDDMA composite resin were almost same as those of the TEGDMA resin.

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The purpose of this study was to evaluate the effectiveness of a [3-(4, 5-dimethylthiazol-2yl)-2, 5-diphenyltetrazolium] bromide (MTT) assay in the toxic evaluation of a compound containing sulfhydryl groups. For this purpose, we performed both MTT and neutral red (NR) assays on 6-(4-vinylbenzyl-n-propyl)amino-1, 3, 5-triazine-2, 4-dithiol (VTD) and compared the results. The results of the MTT assay showed that the cell survival ratio rose higher than the control levels at some VTD concentrations. In addition, it was found that MTT-formazan was formed by VTD in the presence of MTT. These results suggest that VTD might indirectly increase the amount of MTT-formazan by enhacing enzymatic activity in the mitochondrion. The sulfhydryl compound (VTD) did not, however, affect the NR assay. Therefore, the MTT assay should be avoided for cytotoxic examinations of compounds containing sulfhydryl groups.

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It is well-known that the brightness, chroma and hue of dental porcelain change due to firing conditions. Therefore, we measured the spectrum reflection using an automatic goniophoto-meter of the object after the change of the surface and diffused reflection in space during baking occurred. As a result, the peak strength of the suface reflected light without wavelength and the half-range angle of the surface reflected light changed according to the type of porcelain, wavelength and baking condition. Also, the diffused reflection was influenced in all conditions. Conventionally, the surface reflection of porcelain is the same color as irradiated light. However, the color in the periphery of the reflected light at the surface changed, although the peak of the surface reflection was precisely the same color as the irradiated light.

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Solder comprising of titanium, nickel, and indium were experimentally produced to apply to the infrared radiation soldering of titanium. Eutectic structures consisting of nickel and a metallic compound, Ni₃In, were formed in the Ni-In binary alloys containing 10〜30wt% of indium, and only Ni₃In was formed in Ni62In38. The Ti-Ni-In ternary alloys consisted of α-Ti and a metallic compound Ti₂Ni. Solidus and liquidus points of Ni-In alloys decreased with increasing amounts of indium, whereas there were no significant differences in solidus and liquidus points of the Ti-Ni-In ternary alloys. The soldering strength of the titanium bar soldered with Ni-In binary alloys decreased with increasing amounts of indium in the solder. The soldering strengths of Ti60Ni30In10, Ti60Ni25In15, and Ti60Ni20In20 showed excellent soldering strengths (250〜290MPa) and were similar to those of a commercial TiCuNi solder. The specimens having a continuous boundary layer with a high content of indium showed excellent soldering strengths.

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