Faculty Profiles - KIKUCHI Masafumi

Papers - KIKUCHI Masafumi

Division display 1 - 20 of about 49 ／ All the affair displays >>

Otsuka Y., Higashinakao T., Kono H., Kikuchi M. . Monitoring Dental Zinc Oxide Polyacrylate Cement Using Near-Infrared Spectroscopy . Journal of Nondestructive Evaluation44 ( 2 ) 2025.6

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

Scopus

Otsuka Y., Rawal A., Koshy P., Ben-Nissan B., Kono H., Kikuchi M. . Structural transformations in mechanochemically-synthesized strontium-doped hydroxyapatite . Ceramics International 2025

Language：Japanese Publisher：Ceramics International

This study aims to investigate crystallization of strontium-substituted hydroxyapatite upon sintering. A study of mechanochemically-synthesized hydroxyapatite (HAp), doped with strontium at varying levels from 0 to 20 % is presented. The Sr-doped HAp powders were obtained by a mechanochemical method, followed by sintering at 1000 °C. The sintered samples were characterized using a complimentary set of SEM-EDX, XRD, FTIR, Raman, and solid-state NMR techniques. The FTIR spectra of the sintered samples showed a decreasing ν OH vibrational bands with increasing Sr content. This conflict is resolved by multinuclear solid-state NMR which conclusively demonstrates presence of OH− in all samples, and that the strontium doping does not influence the OH− concentration. Sr doping is demonstrated to not be random, with evidence of clustering, but without phase segregation even at the higher Sr loadings. The structural transformations of HAp revealed herein have significant implications in ongoing development of hydroxyapatite based systems, in monitoring the degree of hydroxylation, phase structure and concomitant effects on crystallinity and bioactivity.

DOI： 10.1016/j.ceramint.2025.04.022

Scopus

Otsuka Y., Ito S., Noguchi K., Kono H., Kikuchi M. . Monitoring of self-setting apatite cement using near-infrared spectroscopy: time-course evaluation using machine learning . Journal of the Australian Ceramic Society 2025

Language：Japanese Publisher：Journal of the Australian Ceramic Society

In this study, near-infrared (NIR) spectroscopy, a measurement method not widely used in dentistry, was used to monitor the synthesis of calcium phosphate cement. Tetra calcium phosphate and di calcium phosphate dihydrate were mixed at a Ca/P ratio of 1.67, and water was added dropwise to induce the phase transition to HAp. The reaction conditions were evaluated by measuring NIR spectra every minute for 60 min and every 20 min for 24 h. The obtained NIR spectra were analyzed using singular value decomposition. The synthesized apatite was characterized by measuring XRD, FT-IR, and SEM. In the self-setting apatite cement system, 24-hour monitoring revealed that a phase transition was achieved. NIR monitoring was found to be effective and valuable for evaluating calcium phosphate cements.

DOI： 10.1007/s41779-024-01143-2

Scopus

Itotagawa M., Kono H., Higashinakao T., Sugiura Y., Otsuka Y., Kikuchi M., Nishitani Y. . Adsorption of oral antibacterial agents on zirconia surfaces with different crystal systems . RSC Advances14 ( 36 ) 26457 - 26463 2024.8

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

Higashinakao T, Kono H, Itotagawa M, Sugiura Y, Otsuka Y, Kikuchi M . Preparation and antibacterial evaluation of silver-doped zirconia for enhanced dental restoration performance. . Biomedical materials (Bristol, England)19 ( 5 ) 2024.8

Language：English 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

Otsuka Y, Indo H, Kawashima Y, Tanaka T, Kono H, Kikuchi M . Eichner classification based on panoramic X-ray images using deep learning: A pilot study. . Bio-medical materials and engineering35 ( 4 ) 377 - 386 2024.6

Language：English Publisher：Bio-Medical Materials and Engineering

BACKGROUND: Research using panoramic X-ray images using deep learning has been progressing in recent years. There is a need to propose methods that can classify and predict from image information. OBJECTIVE: In this study, Eichner classification was performed on image processing based on panoramic X-ray images. The Eichner classification was based on the remaining teeth, with the aim of making partial dentures. This classification was based on the condition that the occlusal position was supported by the remaining teeth in the upper and lower jaws. METHODS: Classification models were constructed using two convolutional neural network methods: The sequential and VGG19 models. The accuracy was compared with the accuracy of Eichner classification using the sequential and VGG19 models. RESULTS: Both accuracies were greater than 81%, and they had sufficient functions for the Eichner classification. CONCLUSION: We were able to build a highly accurate prediction model using deep learning scratch sequential model and VGG19. This predictive model will become part of the basic considerations for future AI research in dentistry.

DOI： 10.3233/BME-230217

Scopus

PubMed

Otsuka Y., Kono H., Kikuchi M. . Mechanochemical synthesis of cerium chlorapatite from a mixture of cerium chloride heptahydrate, dicalcium phosphate dihydrate, and calcium hydroxide for biomedical application . Bio-Medical Materials and Engineering35 ( 1 ) 77 - 85 2024.1

Language：Japanese Publisher：Bio-Medical Materials and Engineering

BACKGROUND: Cerium ions promote osteoclastogenesis and activate bone metabolism, while cerium oxide nanoparticles exhibit potent anti-inflammatory properties, making them promising for biomedical applications. OBJECTIVE: The purpose of this study was to develop and evaluate a synthesis method for sustained-release cerium-ion bioceramics containing apatite. Substituted apatite was found to be an effective biomaterial. METHODS: Cerium-containing chlorapatite was synthesized using a mechanochemical method employing dicalcium phosphate, cerium chloride heptahydrate, and calcium hydroxide as raw materials. The synthesized samples were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Raman spectroscopy. RESULTS: Cerium chlorapatite was successfully synthesized in the 10.1% and 20.1% samples. However, at Ce concentrations higher than 30.2%, the samples consisted of three or more phases, indicating the instability of a single phase. CONCLUSION: The method used in this study was found to be more efficient and cost-effective than the precipitation method for producing substituted apatite and calcium phosphate-based biomaterials. This research contributes to the development of sustained-release cerium-ion bioceramics with potential applications in the field of biomedicine.

DOI： 10.3233/BME-230073

Scopus

PubMed

Otsuka Y., Masuzaki T., Nishimura M., Kono H., Kikuchi M. . Modeling of calcium phosphate based on an LCD 3D printer using brushite and calcium hydroxide . Journal of the Australian Ceramic Society 2024

Language：Japanese Publisher：Journal of the Australian Ceramic Society

There is demand for the development of highly functional and flexible bone fillers to treat bone defects. This research aimed to fabricate calcium phosphate implants with a flexible porous design and sufficient compressive stress using a three-dimensional 3D printer. A mixed slurry of dicalcium phosphate, calcium hydroxide, photopolymerized resin, and polyethylene glycol (PEG) was prepared using a planetary ball mill. The slurry was formed into a porous model using a stereolithography-type 3D printer. Upon sintering, the resin and PEG evaporated and/or combusted, yielding a β- tricalcium phosphate (TCP) molding with porosity. This study proposes a novel method for freely molding calcium phosphate implants.

DOI： 10.1007/s41779-024-01076-w

Scopus

Yuta Otsuka, Besim Ben-Nissan, Hiroshi Kono, Tetsuo Sasaki, Masafumi Kikuchi . Mechanochemical synthesis and characterization of strontium substituted apatite for biomedical application . Open Ceramics16 2023.9Reviewed International coauthorship

Masatoshi Takahashi, Masafumi Kikuchi, Yukyo Takada . Grindability of Ti−Nb−Cu alloys for dental machining applications . Metals12 ( 5 ) 2022.5Reviewed

Hiroshi Kono, Masafumi Kikuchi . Analysis of orthodontic wire springback to simplify wire bending . Orthodontic Waves79 ( 1 ) 57 - 63 2020.2Reviewed

Hiroshi Kono, Hiroyuki Arikawa, Syunichi Hamamura, Yasuhiro Sonoda, Masafumi Kikuchi . Effect of Sintering Conditions on Translucency of High Translucent Zirconia . Key Engineering Materials829 49 - 53 2019.12Reviewed

ARIKAWA Hiroyuki, MINESAKI Yoshito, MURAGUCHI Koichi, KONO Hiroshi, KIKUCHI Masafumi . Thermochromism of restorative composite resins . Dental Materials Journal38 ( 2 ) 329 - 336 2019Reviewed

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：The Japanese Society for Dental Materials and Devices

The aim of this study was to clarify the temperature dependence of color, i.e. the thermochromism of restorative composite resins at typical intraoral temperatures. Five brands of restorative composite resins were used. The CIE L*a*b* color values were measured using a spectrophotometer at specimen temperatures of 4, 23, 37, 60, and 80ºC. The temperature dependence of the refractive index of the materials at 4–80ºC were also determined using a refractometer. The values of L* for all materials decreased, and those of a* and b* for most of the materials increased, with increasing temperature. The color difference (ΔE*) for all materials increased with increasing specimen temperatures. The refractive index of the A4 shade of the materials consistently decreased with increasing temperatures. Most of the materials exhibited perceptible thermochromism related to intraoral thermal conditions. Optical properties that change in response to temperature could help explain the thermochromism of materials.

DOI： 10.4012/dmj.2018-047

TAKAHASHI Masatoshi, KIKUCHI Masafumi, TAKADA Yukyo . Mechanical properties and microstructures of dental cast Ti-6Nb-4Cu, Ti-18Nb-2Cu, and Ti-24Nb-1Cu alloys . Dental Materials Journal35 ( 4 ) 564 - 570 2016Reviewed

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japanese Society for Dental Materials and Devices

The mechanical properties —tensile strength, yield strength, elongation after fracture, and Vickers hardness— and alloy phases of the dental cast alloys Ti-6%Nb-4%Cu, Ti-18%Nb-2%Cu, and Ti-24%Nb-1%Cu were investigated. Ti-6%Nb-4%Cu consisted of a single α-phase, while Ti-18%Nb-2%Cu and Ti-24%Nb-1%Cu consisted of α- and β-phases. The tensile strengths, yield strengths, and hardnesses of these alloys were higher than those of Ti-5%Cu and Ti-30%Nb; however, their breaking elongations were smaller. These differences in the mechanical properties are attributable to solid-solution strengthening or to precipitation strengthening by the dual-phase (α+β) structure. Thus, Ti-Nb-Cu alloys are suitable for use in high-strength dental prostheses, such as implantretained superstructures and narrow-diameter implants.

DOI： 10.4012/dmj.2015-354

PubMed

CiNii Research

Masatoshi Takahashi, Masafumi Kikuchi, Yukyo Takada . Mechanical properties of dental Ti-Ag alloys with 22.5, 25, 27.5, and 30 mass% Ag . Dental Materials Journal34 ( 4 ) 503 - 507 2015.8Reviewed

Shouichi Miyawaki, Hiroshi Tomonari, Takakazu Yagi, Takaharu Kuninori, Yasuhiko Oga, Masafumi Kikuchi . Development of a novel spike-like auxiliary skeletal anchorage device to enhance miniscrew stability . American Journal of Orthodontics and Dentofacial Orthopedics 148 ( 2 ) 338 - 344 2015.8Reviewed

INAGAKI Ryoichi, KIKUCHI Masafumi, TAKAHASHI Masatoshi, TAKADA Yukyo, SASAKI Keiichi . Machinability of an experimental Ti-Ag alloy in terms of tool life in a dental CAD/CAM system . Dental Materials Journal34 ( 5 ) 679 - 685 2015Reviewed

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japanese Society for Dental Materials and Devices

Titanium is difficult to machine because of its intrinsic properties. In a previous study, the machinability of titanium was improved by alloying with silver. This study aimed to evaluate the durability of tungsten carbide burs after the fabrication of frameworks using a Ti-20%Ag alloy and titanium with a computer-aided design and computer-aided manufacturing system. There was a significant difference in attrition area ratio between the two metals. Compared with titanium, the ratio of the area of attrition of machining burs was significantly lower for the experimental Ti-20%Ag alloy. The difference in the area of attrition for titanium and Ti-20%Ag became remarkable with increasing number of machining operations. The results show that the same burs can be used for a longer time with Ti-20%Ag than with pure titanium. Therefore, in terms of tool life, the machinability of the Ti-20%Ag alloy is superior to that of titanium.

DOI： 10.4012/dmj.2015-014

PubMed

CiNii Research

Kazuko Nakajo, Masatoshi Takahashi, Masafumi Kikuchi, Yukyo Takada, Osamu Okuno, Keiichi Sasaki, Nobuhiro Takahashi . Inhibitory effect of Ti-Ag alloy on artificial biofilm formation . Dental Materials Journal33 ( 3 ) 389 - 393 2014.6Reviewed

Yukyo Takada, Masatoshi Takahashi, Jun Shiroto, Akira Kikuchi, Masafumi Kikuchi . Laser welding between magnetic stainless steels and titanium as a shield-ring and spacer material . Journal of Japanese Society of Magnetic Applications in Dentistry20 ( 2 ) 1 - 4 2011.12Reviewed

Masafumi Kikuchi, Masatoshi Takahashi, Yukyo Takada . Geometric design method for occlusal outlines of complex class I and Class II inlay cavities . Dental Materials Journal30 ( 5 ) 648 - 654 2011.10Reviewed

　 PREV - NEXT 　

<KIKUCHI Masafumi>

Papers - KIKUCHI Masafumi