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Kashiwa, Japan

Akaike S.,Tsurumi University | Kobayashi D.,Tokyo Institute of Technology | Aono Y.,Tokyo Institute of Technology | Hiratsuka M.,Nanotec Corporation | And 3 more authors.
Diamond and Related Materials | Year: 2016

In orthodontics, it is important to reduce the static friction between brackets and wires in order to enable easy tooth movement. The goal of the present study was to deposit diamond-like carbon (DLC), fluorine-doped DLC (F-DLC), and silicon-doped DLC (Si-DLC) coatings onto the slot surface in stainless steel orthodontic brackets using the plasma-enhanced chemical vapor deposition (PECVD) method and to characterize the frictional property between the coated bracket and wire under dry and wet conditions. In order to characterize DLC-, F-DLC- or Si-DLC-coated surface, XPS, the surface roughness and surface wettability of three deferent surfaces were measured. A nanoindentation test and a scratch test were performed in order to measure the hardness and adhesiveness, respectively, of DLC-, F-DLC- or Si-DLC coatings. The static friction between DLC-, F-DLC-, Si-DLC-coated brackets and 0.019 × 0.025-in stainless steel (SS) orthodontic wires was measured for several angulations under dry and wet conditions using a universal testing machine equipped with a custom-made friction-testing device. The F 1s or Si 2p and Si 2s peaks were observed for F-DLC (27.8 at.%:F) or Si-DLC (26.8 at.%:Si), respectively. There were no significant differences in the surface roughness of the slot surface of the bracket among the four types of specimens. The F-DLC was significantly hydrophobic and Si-DLC was significantly hydrophilic as compared to DLC. Doping the DLC with fluorine or silicon caused the surface hardness to decrease significantly. The results of the present study indicate that DLC, F-DLC and Si-DLC coatings provided a significant reduction in static friction. Among the coatings examined herein, F-DLC-coated bracket exhibited the significantly lowest static friction between the bracket and wire under the wet condition, which was lower than that under the dry condition. The F-DLC coating is highly promising as a means of promoting effective tooth movement and shortening treatment time for orthodontic treatments. © 2015 Elsevier B.V. All rights reserved.

Takatsu M.,Nihon University | Asai T.,Nihon University | Hiratsuka M.,Nanotec Corporation
IEEJ Transactions on Fundamentals and Materials | Year: 2014

A magnetized coaxial plasma gun (MCPG) has been studied in the context of nuclear fusion research, for particle and magnetic helicity injection and spheromak formation through electromagnetically accelerated magnetized plasmoid. On the other hand, most of physical vapor deposition (PVD) techniques have been developed for surface modification and new substance composition in field of electric-appliance, material, semiconductor, etc. However, in the conventional methods, conditions of deposition are limited by productive efficiency and thermal load to the substrate. We proposed a novel PVD method by utilizing electromagnetic acceleration of MCPG. In this study, we deposited Al films on SiO2by the method, and evaluated the deposition rate and the adhesion strength. We confirmed the adhesion strength of about 2.1 times higher than the conventional method. This method can deposit a thin film with high adhesion strength by electromagnetically accelerating particles. © 2014 The Institute of Electrical Engineers of Japan.

Akaike S.,Tsurumi University | Hayakawa T.,Tsurumi University | Kobayashi D.,Tokyo Institute of Technology | Aono Y.,Tokyo Institute of Technology | And 3 more authors.
Dental Materials Journal | Year: 2015

In orthodontics, a reduction in static friction between the brackets and wire is important to enable easy tooth movement. The aim of this study was to examine the effects of a homogeneous diamond-like carbon (DLC) coating on the whole surfaces of slots in stainless steel orthodontic brackets on reducing the static friction between the brackets and the wire. The DLC coating was characterized using Raman spectroscopy, surface roughness and contact angle measurements, and SEM observations. Rectangular stainless steel and titanium-molybdenum alloy wires with two different sizes were employed, and the static friction between the brackets and wire was measured under dry and wet conditions. The DLC coating had a thickness of approximately 1.0 μm and an amorphous structure was identified. The results indicated that the DLC coating always led to a reduction in static friction. © 2015, Japanese Society for Dental Materials and Devices. All rights reserved.

Ohgoe Y.,Tokyo Denki University | Hirakuri K.K.,Tokyo Denki University | Saitoh H.,Nagaoka University of Technology | Nakahigashi T.,Nissin Electric Co. | And 5 more authors.
Surface and Coatings Technology | Year: 2012

In this study, various kinds of diamond-like carbon (DLC) films were classified in terms of their biological responses (specifically the number of adhering cells). Forty three kinds of DLC samples that had been deposited on Si substrate by various physical vapor deposition (PVD) and chemical vapor deposition (CVD) system equipment were obtained at random from coating companies, universities, and public organizations in Japan. Mouth fibroblasts (NIH-3T3) were used to estimate the cellular responses on the DLC samples. During the cell culture, 12 of the DLC samples were peeled off from the Si substrates. As a result, the remaining 31 DLC samples with a wide range of properties were classified into four groups in terms of their number of adhering cells. Group 1 (high density, low sp 2 content, and low hydrogen contents) and Group 2 (low or medium density, high sp 2 content, and low hydrogen contents) had a low number of adhering cells. Group 3 (medium density, and medium sp 2 content, and relatively high hydrogen contents) and Group 4 (low sp 2 content, low density, and a wide range of hydrogen contents) had a wide range of number of adhering cells. Especially, 7 DLC samples in Group 4 had good cell growth. It was shown that this classification is one of the design criteria of DLC film deposition for biomaterials regardless of the various deposition system equipment. It is expected that ordinary DLC users can carefully select a DLC film for specific applications to medical devices using the classification. © 2012 Elsevier B.V.

Tada H.,Tokyo Denki University | Mabuchi Y.,Tokyo Denki University | Hibino M.,Tokyo Denki University | Ohgoe Y.,Tokyo Denki University | And 12 more authors.
Transactions of Japanese Society for Medical and Biological Engineering | Year: 2014

Diamond-Like Carbon (DLC) films have excellent properties such as hemocompatibility, biocompatibility, and in-vivo stability. However, the properties of DLC films strongly depend on deposition conditions, fabrication equipments and deposition methods. To produce required films, a manufacture method and a preparation condition have to be carefully selected. In this study, biocompatibility of DLC films deposited by several kinds of equipments was estimated by the cell culture, and the correlation with DLC film surface state was investigated. By several kind of equipment, 19 types of DLC films were deposited on PS dish. We estimated biocompatibility and surface states for these films. We found that there was no correlation between biocompatibility of DLC films and the result of XPS, or that of contact angle measurements. However, there was strong correlation between biocompatibility and hardness test. This result shows hardness test becomes one of the useful methods to evaluate the biocompatibility of DLC films. © 2014, Japan Soc. of Med. Electronics and Biol. Engineering. All rights reserved.

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