The purpose of this study was to investigate the effectiveness of leucite crystals ion-exchanged with rubidium on the mechanical properties of glassy porcelain. For ion-exchange, a mixture of high-pure natural leucite (KAlSi₂O₆) powder and RbNO₃ were heat-treated at 450°C (RLa) or 650°C (RLb) for 1 hour. The density of leucite increased as a result of the rubidium ion-exchange treatment. Polymorphic transformation temperatures of the ion-exchanged leucites were low compared with the unmodified leucite. Composite porcelains were prepared by blending each leucite (30vol%) with “Component No.3” frit of Weinstein et al. patent. The flexural strength and fracture toughness of the glass-only and composite porcelains were measured by a three-point bending test and indentation technique. ANOVA and post hoc multiple comparisons test revealed that the flexural strength and fracture toughness of the composite porcelain containing RLa were significantly higher (p<.05 and p<.01, respectively) than those of the other groups. The results suggested that the rubidium-ion-exchanged leucite (RLa) could be a better reinforcing agent for dental porcelain.

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XPS and NMR analyses were done on the CaO-Al₂O₃-SiO₂ and CaO-Al₂O₃-SiO₂-CaF₂ glasses to investigate the effect of fluoride on the glass structure. The XPS spectra showed that most of of the fluoride combined with Ca and Al or existed as a free ion in the glasses. The number of F per Ca atom and the fraction of free F^- ion decreased with increasing Al/(Al+Si) ratio in the glasses with Ca/Al=0.5. The fraction of free F^- ion increased at high CaO content in the glasses containing about 45mol% SiO₂. The chemical shift of the fluoride-containing glasses in ²⁹Si NMR spectra was smaller than that of the non-fluoride glasses. The chemical shift of the glasses in ²⁷Al NMR spectra also showed the same tendency as in ²⁹Si NMR spectra. The addition of fluoride caused an increase in the average number of bridging oxygen atoms in the aluminosilicate glass network. However, the average number of Al around a SiO₄ tetrahedron (n) decreased in the species, Si-(O-Si)_4-n(O-Al)_n.

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To obtain full 3-D shape data of a orthodontic dental cast, high-speed measuring equipment with a line laser and a precise goniometer were used, and a program to connect the measured data was developed. Initially, the accuracy of the equipment and the goniometer was examined and confirmed to be suitable for clinical use.
Two upper dental casts with and without crowding in the anterior segment were measured from two directions, i.e. the occlusal and labial sides, and the occlusal data were connected by an original program to the labial data at a boundary point with the largest Z-diff, which showed the largest difference in the height (Z) direction between the two neighboring data.
The proposed algorithm to find the largest Z-diff was confirmed to work effectively in both casts, and the entire 3-D data of the casts was acquired satisfactorily except for the labial surfaces of the lateral incisors which were not measured from either direction on the cast with severe crowding.

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The purpose of this study was to evaluate the resin bonding to dentin irradiated by an Er: YAG laser. The bond strength of a light-cured adhesive resin to dentin irradiated at 126mJ was measured with the micro-tensile bond test. Scanning electron microscopy was used to investigate the bonded interfaces and the morphological changes to irradiated dentin caused by 37% phosphoric acid etching. The irradiated dentin exhibited bond strengths comparable to those of cut-dentin, with or without acid etching. The irradiated dentin surfaces were free of smears and plugs, and the dentinal tubules were open. Additionally, phosphoric acid etching demineralized the irradiated surface slightly, leaving a rough intertubular dentin surface and substantial amount of peritubular dentin. The Er: YAG laser affected not only the dentin surface, but also the subsurface. The laser irradiation increased the acid resistance of the peritubular dentin.

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The interaction of thymol with dipalmitoylphosphatidylcholine (DPPC) liposomes was studied by ¹H-NMR spectroscopy. It was found that thymol was easily interpregnated into DPPC liposomes and then caused movements of acyl chains of DPPC liposomes when thymol was added directly to DPPC liposomes from the outside, resulting from the fact that proton signals of thymol shifted to a higher field and those of the phosphodiester head group and acyl chains of DPPC were observed.
No proton signals of thymol were not observed in the liposome system prepared by directly thymol acting to DPPC; Thymol/DPPC (1:1 molar ratio) liposomes and Thymol/DPPC/Cholesterol (2:1:1) liposomes, indicating the complete disruption of the phospholipid bilayer with formation of mixed thymol lipid micelles or other aggregates.

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