Authorship：Lead author   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

Scopus

PubMed

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

Scopus

PubMed

Language：English   Publisher：日本再生歯科医学会  

医療分野への応用が期待されているテラヘルツ波を、歯髄保存治療に応用できる可能性について検討した。深在性う蝕治療において歯髄切除を避けるためには、う蝕象牙質の残存量と窩洞の歯髄への距離を測定することが有用であるため、歯科治療への応用の予備研究として、エナメル質と象牙質におけるテラヘルツ波の伝播速度を測定した。対照として、アパタイトの天然単一結晶と熱間等方圧(HIP)処理粉末アパタイトを測定した。エナメル質と象牙質は異なる伝播速度を示した。検体中のアパタイトの密度に依存してテラヘルツ波の伝播速度が上昇するので、口腔のエナメル質と象牙質だけでなく、石灰化の異なるう蝕象牙質も識別することができると考えられた。

Language：English   Publisher：Japanese Association of Regenerative Dentistry  

<p>The terahertz wave, which is expected to be used in the future medical field, was examined for the possibility of being applied to conservative pulp treatment. For example, in order to avoid pulpectomy in the deep caries treatment, it is extremely useful to detect the remaining amount of carious dentin and the distance to the pulp in the cavity. As a pilot study of application to dental treatment, the propagation velocity of terahertz waves in enamel and dentin was measured. As controls, natural single crystal of apatite and HIP-treated powder apatite were also measured. As a result, enamel and dentin had different propagation velocities. It suggests that not only enamel and dentin in the oral cavity but also sound dentin and carious dentin with different calcification degrees can be identified by terahertz waves because the propagation rate increases depending on the density of apatite in the sample.</p>

DOI： 10.11223/jarde.19.15

CiNii Research

Event date： 2024.10

Language：Japanese   Presentation type：Oral presentation (general)  

Event date： 2024.5

Language：Japanese   Presentation type：Poster presentation  

Event date： 2024.4

Language：Japanese   Presentation type：Oral presentation (general)  

Event date： 2023.12

Language：English   Presentation type：Poster presentation  

Country：Viet Nam  

Event date： 2023.10

Language：Japanese   Presentation type：Oral presentation (general)  

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

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

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