Eri MIURA

The aim of the present research was to develop a new dental titanium alloy with good castability and biocompatibility. Since Zr is known to have good biocompatibility and form a continuous solid solution with Ti, we selected Zr as an additive element. Also, Sn is expected to have the stabilizing effect of the alpha-phase. Based on this information, we prepared ternary Ti-Zr-Sn alloys with different compositions. Castability, porosity, tensile strength, and crystal structure of the experimental Ti-Zr-Sn alloys were examined. The results showed that the Ti-Zr-Sn alloys possess excellent castability and tensile strength exceeding twice that of pure Ti. This evidence suggests that Ti-Zr-Sn alloys can be used as dental casting alloys.

Fractal analysis by the box-counting method was applied for quantitative understanding of the mechanisms of grain boundary reactions in a dental high-karat gold alloy for porcelain bonding and in a dental silver-palladium-gold-copper alloy for cast crowns. The morphology of grain boundary precipitates, namely nodules, could be described by fractal dimensions of 1 to 2. The grain boundary reaction progressed in relation to increasing nodule and fractal dimension, which corresponded to increase of the morphological complexity. The increase in fractal dimension preceded the increase in volume ...

Fractal analysis by the box-counting method was applied for quantitative understanding of the mechanisms of grain boundary reactions in a dental high-karat gold alloy for porcelain bonding and in a dental silver-palladium-gold-copper alloy for cast crowns. The morphology of grain boundary precipitates, namely nodules, could be described by fractal dimensions of 1 to 2. The grain boundary reaction progressed in relation to increasing nodule and fractal dimension, which corresponded to increase of the morphological complexity. The increase in fractal dimension preceded the increase in volume fraction of the grain boundary precipitates in both isothermal and the anisothernal annealing.

After degassing on gold-coated titanium, Ti3Al and Ti3Au layers were formed in titanium side. Thickness of gold-coated layer was increased. Gold-coated layer changed into Au-Ti intermetallic compounds layer. After porcelain fusing, formation of titanium-deficient layer in titanium side was suppressed. Diffusion of Ti cation into porcelain seemed to be prevented.