The arch form is indispensable for clinical application of the Fiber−Reinforced−Plastic （FRP） wires being developed in combination with biocompatible CaO−P₂O₅−SiO₂−Al₂O₃（CPSA ） glass fibers and polymer matrix. Since the production is limited to a straight form ill the conventional hot drawing method, light polymerization method and urethanedimetha−crylate （UDMA ） resin were adopted for the fabrication of arch form FRP wires in this study, using the ready−made arch form metal wire. Dimensional accuracy and mechanical properties were then investigated. Inter width of the FRP arch wires was smaller by 0.1−0.2 mm （in front） and 0.4−0.7 mm （in rear） compared to the original model, The cross sectional form was uniformly round (0.47−0.48 mmφ). Dimensional accuracy in the molding was thus sufficiently good. OIl flexural test, Young's nioclulus could be controlled in the range of 5−40 GPa, by changing the volume fraction of glass fiber 10−60％. The realization of an arch form FRP wire would contribute to its ap Plication to clinical treatment.

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　To evaluate the flow of hydrophilic polyaddition−type silicone impression materials before set, characterization of the components and measurements of the flow characterjstics were performed. Elemental analysis, determination of the content and size distribution, and SEM ovservation of the fillers seperated from pastes of borh material were performed together with infrared analysis and determination of molecular weight distribution of each prepolymers extracted from the pastes. 　The kind, morphology, content, and size of the fillers and chemical structure of the prepolymers included in the materials tested did not differ from the previously tested materials of the same type, whereas those are featured by narrow dispersion in molecular weight distribution of the prepolymers. The pastes were less viscous and less thixotropic compared to the previously tested pastes. These findings indicate the materials tested would be easy to mix using manual equipment. Furthermore, these materials would have fine reproducibility for oral tissues irnpression with the aid of hydrophilicity. These features were attributed to the lower molecular weight and narrow dispersion range.

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As alternative alloys to Ag−Pd−Cu−Au system alloys, low karat gold alloys consisting of 47.25〜22.33mass% Au −30.70〜48.62mass%Ag−12〜19mass%Cu−2mass% Pt−5 mass% Pd − 2mass% Zn−1 mass% In−0.05 mass% Ir were made. The heat treatment effects, Vickers hardness, tensile 　strength, elongation, and fatigue strength were investigated for the specjmens made by centrifugal casting with a natural gas−oxygen torch. It was found from the results that all experimental alloys had potential for heat treatment. Within the components of the experimental alloys, Vickers hardness, tellsile strength, and fatigue strength increased with the decrease of the gold content, and were similar or much greater than those of commercially available Ag−Pd−Cu−Au system alloys. On the contrary, the elongation increased with the decrease of the gold content. We found that experimental alloys containing over 30 mass% gold content were favorable as alternatives tothe Ag−Pd−Cu−Au system alloys

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　In this investigation, the marginal fitness of a composite resin crown, fabricated by the dental CAD/CAM system, was evaluated. Eight composite resin crowns were fabricated for 8 abutment plaster models, by the dental CAD/CAM system, and composite resin crowns without any adjustment were cemented to each abutment tooth model. After embedding in epoxy resin, they were sectioned into 8 blocks. For every sample, the marginal cement thickness of 16 sections was measured using an optical microscope. Also, the marginal regions of th composite resin and the ceramic crowns were examined with a scanning electron microscope, As a result, the mean of the cement thickness for the composite resin crowns was 45 micro meters. The margins of these crowns were chipped slightly, but less chipped than ceramic crowns. This indicated that composite resin block was well−suited for milling.

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　　From the viewpoint of increasing palladium prices and expression of allergy, the development of low palladium alloys is expected. In this study, 5mass% Pd and 22−47mass% Au with silver and copper eutectic collstituent alloys were experimentally developed. Measurements were carried out on the amount of released element in a mixed solution of 0.1 mol/L lactic acid and 0.1 mol/L NaCl, the potentiodynamic polarization profile in 0.9% NaCl solution and a tarnish test in 0.1 mol/L sodium sulfide. Results were compared with commercial gold−silver−palladium alloy and examined comparatively. As a result, transpassive potential decreased with the reduction of gold content, and was comparable to commercial gold−silver−palladium alloy with above 30 mass% Au alloy. In addition, tarnish resistance was equivalent to commercial gold−silver−palladium alloy by more than 40 mass% Au alloy.

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