Language：Japanese   Publisher：Journal of Nondestructive Evaluation  

This study aims to investigate the reaction kinetics of polycarboxylate cements using NIR spectroscopy with chemometrics. To achieve 100% inspection of medical devices and drugs, it is desirable to develop non-destructive, non-contact quality control methods. One effective method for this is chemometrics, which uses near-infrared spectroscopy and chemometrics. A dental cement, polycarboxylate cement, was prepared, and the spectral changes from 1 min to 15 min were observed using NIR spectroscopy. The obtained spectra were evaluated by two-dimensional correlation spectroscopy. Carboxylate changes in the cement were analyzed using principal component analysis, and a score plot against loadings and time was shown. It was suggested that the hardening mechanism of cement can be plotted as a pseudo-first-order reaction.

DOI： 10.1007/s10921-025-01185-x

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Language：Japanese   Publisher：Biomedical Materials (Bristol)  

Because of its superior strength, esthetic properties, and excellent biocompatibility, zirconia is preferred for dental prosthetic such as crowns and bridges. However, zirconia crowns and bridges are susceptible to secondary caries owing to margin leakage. Silver is a well-known antibacterial agent, making it a desirable additive to zirconia crowns and bridges for secondary caries prevention. This study focuses on imparting zirconia composite with antibacterial properties to enhance its protective capacity in dental restorations. We used the sol-gel method to dope Ag into zirconia. Silver-doped zirconia powders were prepared at Zr:Ag molar ratios of 100:0,100:0.1, 100:0.5, 100:1, 100:3, and 100:5 (respective samples denoted as Ag-0, Ag-0.1, Ag-0.5, Ag-1, Ag-3, and Ag-5) and were subjected to firing at various temperatures (400 °C-1000 °C). We performed x-ray diffraction to investigate the crystal phase of these powders and x-ray fluorescence and field emission scanning electron microscopy to analyze their elemental composition and surface morphology, respectively. Moreover, we performed spectrophotometry to determine the L*a*b* color values, conducted dissolution tests, and quantified the Ag content through inductively coupled plasma optical emission spectroscopy. In addition, we studied the antibacterial activity of the samples. Analyses of the samples fired at ⩽600 °C revealed a predominantly white to grayish-white coloration and a tetragonal crystal phase. Firing at ⩾700 °C resulted in gray or dark gray coloration and a monoclinic crystal phase. The Ag content decreased after firing at 900 °C or 1000 °C. Ag-0.5 and above exhibited antibacterial activity against both Escherichia coli and Staphylococcus aureus. Therefore, the minimum effective silver-doped zirconia sample was found to be Ag-0.5. This study allows the exploration of the antimicrobial potential of silver-doped zirconia materials in dental applications such as prosthdontical lining materials, promoting the development of innovative restorations with protective capacity against secondary caries.

DOI： 10.1088/1748-605X/ad6ac3

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Language：Japanese   Publisher：RSC Advances  

Zirconia ceramics are widely used as dental prosthetics owing to their high biocompatibility, excellent mechanical strength, and aesthetic properties similar to color tones of natural teeth. However, there exists a growing demand for the facile attachment of antibacterial properties in long-term dental restoration. Thus, in this study, we evaluated the adsorption ability of cetylpyridinium chloride (CPC) and benzalkonium chloride (BKC)—quaternary amines widely used as antibacterial substances in commercial toothpaste and other oral care products—onto zirconia surfaces with tetragonal and monoclinic crystal structures. Although tetragonal zirconia has been widely used in dental prosthetic materials such as crowns etc., monoclinic zirconia has also been used under oral conditions because of long-term implantation. When antibacterial molecule loading on zirconia powders under simulated oral conditions, it was revealed that monoclinic zirconia adsorbed approximately five times more CPC and BKC per unit area compared with that of tetragonal zirconia. Moreover, in tetragonal zirconia, the adsorption amounts of both CPC and BKC increased slightly with growing Y2O3 content as a stabilizer. This phenomenon was attributable to the formation of complexes between rare earth elements (REE) such as Y2O3 in zirconia and quaternary amines such as CPC and BKC. In this study, the antibacterial molecular adsorption ability of dental zirconia was observed, and new advantages of zirconia in dental applications were discovered.

DOI： 10.1039/d4ra04084h

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Event date： 2024.11

Language：English   Presentation type：Poster presentation  

Venue：Kampar   Country：Malaysia  

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Event date： 2023.12

Language：English   Presentation type：Poster presentation  

Venue：Ho Chi Minh   Country：Viet Nam  

Event date： 2023.12

Language：English  

Venue：Ho Chi Minh   Country：Viet Nam  

Language：Japanese  

Language：Japanese  

Award type：Award from international society, conference, symposium, etc.  Country：Malaysia

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Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

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Award type：Award from international society, conference, symposium, etc.  Country：Viet Nam

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Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

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