Papers by Author: Hideyuki Aoki

Abstract: Diamond-like carbon (DLC) films were deposited onto UHMWPE and PMMA substrates using plasma CVD process. To improve adhesion of DLC films, substrates were treated plasma before DLC deposition. Samples were analyzed by ball-on disk tester, atomic force microscopy (AFM), and scratch test. Wear and scratch resistance of DLC-coated each substrates were evaluated and showed good results.

Abstract: TiO2 and HA thin film double coating has been proposed. The TiO2/HA thin film was coated on the glass by a Radio Frequency magnetron sputtering, and the characteristic of the thin film has been studied. The absorption of Formaldehyde (HCHO) gas in the TiO2/HA thin film was detected by gas chromatography, and the sterilization of Escherichia coli (E. coli) was evaluated in the antibacterial test. In the deodorization test, HCHO gas remained 0[%], 11[%] and 85[%] for TiO2/HA thin film, TIO2 thin film and thin film respectively. The sterilization result shows that E. coli for TiO2/HA thin film and HA thin film decreased 89[%] and 75[%] respectively.

Abstract: A variety of dental devices such as orthodontics, artificial teeth are implanted in oral cavity for long term. The implant coated with protective films, which can reduce corrosion and wear, may prevent the problems described above and extend the lifetime of implants to the benefit of the patients. Diamond-like carbon films have extreme hardness, low friction coefficients, chemical inertness, and high-corrosion resistance. Moreover, these properties make the good candidates as biocompatible coatings for dental devices. In this study, DLC films using the plasma CVD method deposited on acrylic resin and orthodontic archwires have investigated to detect the Ni release from the wires and to estimate cell growth in E-MEM immersed acrylic plates. After 6 months, the concentration of the nickel release from DLC-coated wire and Non-coated wire was 150 [ppb] and 933 [ppb], respectively. Results indicated DLC films inhibit the release of these materials, and prevent degradation of these materials in the solution.

Abstract: Hydroxyapatite (HA) was coated onto titanium substrates using radio frequency sputtering, and the coated HA films were crystallized in an autoclave at 110 °C using a low temperature hydrothermal method. The crystallinity, the Ca/P ratio, and the surface of the films were observed using XRD, EDS, and SEM, respectively. From the XRD patterns, a sputtered film after the hydrothermal treatment had crystallized after 24 h, and the Ca/P ratio decreased from 2.43 ± 0.07 to 1.75 ± 0.11. The growth rate of osteoblast cells was used for cell culture. Among control, titanium and hydrothermally treated film, there was no significant difference in the cell growth rate. However, the growth rate was suppressed on the as-sputtered film.

Abstract: In this paper, a low concentration of Hydrogen Peroxide (H2O2) was added to the hydroxyapatite ceramics to develop HA/H2O2 compound. The HA/H2O2 was tested for the whitening and deodorizing ability. HA/H2O2 composite was added with glycerin and was tested on the enamel layer for lightness changes on the tooth layer. The lightness result was compared with 100[ppm] of H2O2 treatment by Spectro Color Meter and enamel layers structure observation by optical microscope. In deodorization test, 20[g] of clove garlic and slice garlic were identified for garlic aroma peak. 20[g] of HA/H2O2 compound, HA alone and charcoal respectively were tested for the garlic aroma adsorption ability. Identification and quantification of the garlic aroma peak area decrease was observed by gas chromatography. In the whitening result, HA/H2O2 compound and H2O2 alone treatment obtained 68 and 67 respectively. From the structure observation, HA/H2O2 composite treatment was the best since the smooth and unharmed enamel layer of the tooth was observed. Deodorization ability for HA/H2O2 compound has the similarity rate as charcoal at 82.3[%]. The HA/H2O2 composite has an ability of whitening and deodorizing at even low concentration.