[Show abstract][Hide abstract] ABSTRACT: Objectives
Specific materials when used in the manufacture of dentures can enhance the elimination of micro-organisms to promote oral hygiene. We used Candida albicans adhesion assays, methylene blue (MB)-decomposition tests and mechanical property tests to evaluate the photocatalytic properties of acrylic resin containing fluoridated apatite-coated titanium dioxide (FAp-TiO2) after treatment with ultraviolet A (UVA) irradiation. Background
Conventional denture cleaning methods are unable to completely eliminate micro-organisms from dentures. Materials and methodsTest specimens were prepared using acrylic resin containing three types of TiO2 powder [FAp-TiO2, titanium dioxide (TiO2) and hydroxyapatite-coated TiO2 (HAp-TiO2)]; n=96. In the adhesion assay, test specimens were incubated in a fungal suspension and subjected to UVA irradiation, and the number of attachments of C.albicans on the test specimens was counted. The MB-decomposition test and the three-point bending test were then performed to assess the photocatalytic effects of the FAp-TiO2-containing acrylic resin. ResultsFluoridated apatite-coated titanium dioxide-containing acrylic resin demonstrated superior effectiveness in inhibiting C.albicans adherence as well as in decomposing MB. In the three-point bending test, the resin showed a smaller decrease in flexural strength compared with TiO2- or HAp-TiO2-containing acrylic resin. Furthermore, UVA irradiation for 360h did not significantly influence its flexural strength or elasticity modulus as compared with the control; this fulfils the requirements of International Organization for Standardization 1567:1999. Conclusion
Fluoridated apatite-coated titanium dioxide-containing acrylic resin is a clinically suitable material that promotes proper denture hygiene, particularly for elderly persons requiring nursing care or who have a decreased ability to perform normal activities of daily living.
[Show abstract][Hide abstract] ABSTRACT: It is well known that clinical bleaching can be achieved with a solution of 30% hydrogen peroxide (H2O2) or H2O2/titanium dioxide (TiO2) combination. This study examined the hypothesis that TiO2 coated with hydroxyapatite (HAp-TiO2) can generate reactive oxygen species (ROS). ROS are generated via photocatalysis using electron spin resonance (ESR). The bleaching properties of HAp-TiO2 in the presence of H2O2 can be measured using hematoporphyrin litmus paper and extracted teeth. We demonstrate that superoxides (O2(•-)) and hydroxyl radicals (HO(•)) can be generated through excitation of anatase TiO2, rutile TiO2, anatase HAp-TiO2, and rutile HAp-TiO2 in the presence of H2O2. The combination of R HAp-TiO2 with H2O2 produced the highest level of HO(•) generation and the most marked bleaching effects of all the samples. The superior bleaching effects exhibited by R HAp-TiO2 with H2O2 suggest that this combination may lead to novel methods for the clinical application of bleaching treatments.
No preview · Article · May 2012 · Dental Materials Journal
[Show abstract][Hide abstract] ABSTRACT: It is well known that clinical bleaching can be achieved with a solution of 30% hydrogen peroxide (H2O2) or H2O2/titanium dioxide (TiO2) combination. This study examined the hypothesis that TiO2 coated with hydroxyapatite (HAp-TiO2) can generate reactive oxygen species (ROS). ROS are generated via photocatalysis using electron spin resonance (ESR). The bleaching properties of HAp-TiO2 in the presence of H2O2 can be measured using hematoporphyrin litmus paper and extracted teeth. We demonstrate that superoxides (O-2(center dot-)) and hydroxyl radicals (HO center dot) can be generated through excitation of anatase TiO2, rutile TiO2, anatase HAp-TiO2, and rutile HAp-TiO2 in the presence of H2O2. The combination of R HAp-TiO2 with H2O2 produced the highest level of HO center dot generation and the most marked bleaching effects of all the samples. The superior bleaching effects exhibited by R HAp-TiO2 with H2O2 suggest that this combination may lead to novel methods for the clinical application of bleaching treatments.
No preview · Article · May 2012 · Dental Materials Journal
[Show abstract][Hide abstract] ABSTRACT: We examined the apatite precipitate ability of CaO-MgO-SiO 2 compounders. Synthesized materials were Diopside, Akermanite, Pseudowollastonite, Forsterite and Protoenstatite. Materials were synthesized with solid solution method. Materials soaked to pseudo body solution stirred at 37°C for 1 hour. Diopside, Pseudowollastonite and Protoenstatite precipitated apatite. These materials got precipitation on surface and had the peak of 31-32° by X-ray diffraction patterns. In addition, Diopside, Pseudowollastonite and Protoenstatite eluted less magnesium. These experimental results seem to mean that less magnesium elution can cause more apatite precipitation. However, magnesium consists in vivo and has possibilities to improve biocompatibility. Diopside has ability of elute magnesium and precipitate apatite. In addition, Diopside can make hybrid with titanium. From these results we observed Diopside that could make hybrid with titanium by sol-gel method is appropriate for biomaterials.
No preview · Article · Jan 2012 · Journal of the Australian Ceramic Society
[Show abstract][Hide abstract] ABSTRACT: New bone formation around implants is one of preferable conditions for the successful implantation. In this study, formable carbonate apatite ceramics were prepared and implanted in cavities (φ 400 μm, depth 400 μm) on the surface of pure titanium implant (ASTMB348-GR2) to enhance new bone formation around the titanium implant.
No preview · Article · Jan 2011 · MRS Online Proceeding Library
[Show abstract][Hide abstract] ABSTRACT: This study was to develop a titanium dioxide (TiO(2))-coated implant abutment, surface with ultraviolet (UV) light-induced hydrophilicity and investigate the initial response of human, fibroblasts to the surface modification.
Commercially pure titanium (JIS 2 grade) disks were coated with TiO(2) to various, thicknesses (1, 2 or 3 μm) using peroxotitanium acid solution. The surface characteristics of each disk, were examined with X-ray diffraction (XRD), surface roughness equipment and scanning electron, microscopy (SEM). The hydrophilic change of each disk was determined by the contact angles at 0-24h, after 24-h UV irradiation. The biological response at the surface of each disk was examined by using, human periodontal ligament fibroblasts (HPLFs). The data were statistically analyzed with analysis of variance (ANOVA) and multiple-comparison tests.
The TiO(2)-coated disk surface had an anatase structure. Surface roughness did not differ, significantly among the disks; the surface morphology was smooth and had a hydrophilic or superhydrophilic, status. HPLF proliferation significantly increased on the TiO(2)-coated disks compared with the uncoated disks and depended upon the coated film thickness.
An anatase TiO(2)-coated surface under UV irradiation markedly improves the initial response of human fibroblasts.
[Show abstract][Hide abstract] ABSTRACT: This study sought to decrease dishing and erosion as they cause reduced yield in copper chemical mechanical polishing (Cu-CMP), which is a multilayer interconnect process that is a part of the overall semiconductor manufacturing process. We prepared a polishing pad that incorporated abrasive grains (AC Pad) and used a chelating resin in the matrix (resin). Moreover, we studied whether this polishing pad was applicable to the Cu-CMP process. Results indicated that the pad was selectively abrasive to copper (Cu) and that in the polishing of patterned wafers, it vastly decreased dishing to 1/8th and erosion to half of their respective levels in abrasive polishing. Therefore, the pad has considerable potential for use in Cu-CMP.
No preview · Article · Apr 2009 · Precision Engineering
[Show abstract][Hide abstract] ABSTRACT: Influences of supersaturation in a tetraethyl orthotitanate (TEOT) solution on the degree of crystallinity of product particles in the case of a hydrolysis reaction of TEOT were indicated and the crystallization phenomena of anatase titanium dioxide (TiO2) were discussed. Changes in saturation ratios with experimental durations were examined for the various amount of acetylacetone added into a TEOT solution. At the initial stages of TEOT hydrolysis operations, the degree of crystallinity of product particles was lower for the longer hydrolysis durations but the degrees became almost constant in the later stages of TEOT hydrolysis operations, although the supersaturation of titanium oxide in a TEOT solution was remained. Rapid increase in supersaturation of titanium oxide in a TEOT solution and consequent nucleation of amorphous titanium oxide would be restrained by addition of acetylacetone into a TEOT solution because the concentrations of titanium oxide in a saturated TEOT solution increased with the amount of acetylacetone.
No preview · Article · Sep 2008 · Ceramics International
[Show abstract][Hide abstract] ABSTRACT: It is known that bones and teeth are mostly composed of hydroxyapatite (HAp) and iron is present in them as a trace element. In order to search for helpful information for understanding the behavior of trace iron element in bones and teeth, very small amounts of iron containing HAp(FeHAp) were synthesized from a modified pseudo-body solution at low temperature. The effects of iron on the structural and photo-absorption properties of FeHAp were characterized by XRD, the Rietveld structural refinement, TEM and UV-vis photo-absorption spectroscopy. The results suggested that Fe(III) ions with high spin could get into the apatite structure and FeHAp with a pure apatitic phase could be obtained. At the same time, iron could modify the photo-absorption property of FeHAp. Compared with the pure HAp material, the prepared iron containing materials showed obviously photo-absorption property in the UV light region.
Preview · Article · Aug 2008 · Journal of Materials Science Materials in Medicine
[Show abstract][Hide abstract] ABSTRACT: Anatase titanium dioxide (TiO2) photocatalytic thin films were directly formed on glass slide and commercial dental mirror substrate surfaces by a hydrolysis
of titanium alkoxide, and the hydrophilicity, the degree of oxidizing power and the transparency of the anatase TiO2-coated substrate surfaces. The contact angles of water and the decomposition rates of methylene blue on the anatase TiO2 photocatalytic thin films improved with the increasing duration of a tetraethyl orthotitanate (TEOT) hydrolysis, but they
hardly changed for the longer duration. The reflectance of anatase TiO2 photocatalytic thin films coated on glass slide substrate surfaces was higher as the duration of a TEOT hydrolysis increased.
Similar tendencies concerning hydrophilicity and transparency were recognized in cases of commercial dental mirror substrate
surfaces. A hydrolysis of titanium alkoxide obtained superhydrophilic and antibacterial treatments with excellent transparency
on commercial dental mirror substrate surfaces.
No preview · Article · Aug 2007 · Journal of Coatings Technology and Research
[Show abstract][Hide abstract] ABSTRACT: An acid resistant fluoroapatite coated titanium dioxide (FAp-TiO2) was synthesized by adding a fluoride ion (F-) to hydroxyapatite (HAP), in order to avoid dissolution of the HAP at an acidic atmosphere. In this study, the optimization of synthetic conditions of FAp-TiO2 was investigated in terms of the amount of the fluorine (F-) added to the simulated body fluid, the reaction temperature and the time. The addition of F- to simulated body fluid was performed after coating HAP on the surface of TiO2 surface. The crystallinity of FAp phase generated on the TiO2 was strongly affected by changing the reaction conditions. The optimized synthetic conditions of FAp-TiO2 as photocatalyst were the addition of 0.25 mM-0.5 mM F- in the fluid and then the reaction time for 3 h at 60 degrees C. The adsorptivity and the photocatalytic activity of the FAp-TiO2 in the optimum conditions were investigated using the butyric acid and trimethylamine as model solutions. Consequently, the FAp-TiO2 could obtain higher adsorptivity and photocatalytic activity for trimethylamine, rather than the uncoated TiO2.
No preview · Article · Feb 2007 · Journal of the Ceramic Society of Japan
[Show abstract][Hide abstract] ABSTRACT: The simplification of the cleaning process of plastic containers used in the storage and/or distribution of fruits or vegetables is important. We coated a plastic container with an apatite-coated titanium dioxide photocatalyst (TiO2–Ap container), and examined its disinfecting efficacy under UV irradiation from black light. The disinfecting efficacy of the TiO2–Ap container on diluted drops evaporated from spinach (suspension) was examined. Changes in the microbial populations of the total aerobic bacteria, coliform bacteria, and moulds and yeasts in the TiO2–Ap container were assayed at 25°C for 24h (UV-A intensity of 0.2 and 0.4mWcm−2). The results showed that all of the microbial populations in the TiO2–Ap container decreased with irradiation time and then reduced to uncountable levels. It was found that the increase in UV-A intensity enhanced the disinfecting efficacy.
[Show abstract][Hide abstract] ABSTRACT: We are interested in developing novel multifunctional biomaterials applied for dental surgery and the fabrication of artificial bone scaffolds with a controlled pore structure. Hydroxyapatite (noted HAp) is a useful biomaterial due to its good biocompatibility. Small amount of iron has been known to influence the crystallinity and solubility of HAp. In this study, various kinds of trace iron containing HAp (noted FeHAp) were synthesized by adding an aqueous solution of iron nitrate into a modified pseudo-body solution with an excess of phosphate ion concentration. The crystal structures of FeHAp were refined by the Rietveld analysis. The optical properties of FeHAp were measured by UV-vis spectroscopy. The results indicate that the cell parameters become longer and the photo-absorption become stronger with increasing iron within the studied composition range. This implies that FeHAp is possible to have additional functions comparing with plain HAp when is used as a biomaterial. In this paper, syntheses and characterization of the novel FeHAp are reported.
[Show abstract][Hide abstract] ABSTRACT: An acid resistant fluoroapatite (FAp) coated titanium dioxide (TiO2) was synthesized by adding a fluoride ion (F-) to hydroxyapatite (HAP), in order to avoid dissolution of the HAP at an acidic atmosphere. In this study, different methods of adding F- to the apatite in a simulated body fluid were tested; one was synthesized by coating a simulated body fluid including Ca2+, PO43- and F- to the TiO2 (method 1), and another method was by mixing the F- after coating a simulated body fluid without the F- to the TiO2 (method 2). The apatite crystalline phase of the coated TiO2 was found to increase with F-, by using a XRD and a FT-IR. The size of crystalline apatite was strongly affected by the method of adding F-. The size of the crystalline synthesized by method 1 was larger than that by method 2. The photocatalytic activities of the apatite coated photocatalysts to organic substrates such as propionic acid were evaluated using an ion chromatography. The deterioration of FAp coating during photooxidation of the propionic acid with an UV-irradiation was largely suppressed compared with that of the HAP coating.
No preview · Article · Oct 2006 · Journal of the Ceramic Society of Japan
[Show abstract][Hide abstract] ABSTRACT: Thin films of anatase titanium dioxide (TiO2) were prepared on slide glass substrate surfaces by a titanium alkoxide hydrolysis operation, and the hydrophilicity and the transparency of their films were examined. The contact angles of water and the transmittances of visible light for their substrates changed with the duration of tetraethyl orthotitanate (TEOT) hydrolysis operations. They were influenced by the thickness of the films and the size of the deposited particles on the silicon dioxide-coated slide glass substrate surfaces. The contact angles also changed with the irradiating duration of ultraviolet light. When acetylacetone was added to a TEOT solution, the contact angles on the thin films became larger and the transparency was better during the same duration of TEOT hydrolysis operations. On addition of acetylacetone, nucleation of TiO2 particles at the initial stages of TEOT hydrolysis operations was restrained and, subsequently, the supersaturations of TiO2 in the solution became comparatively higher in the later stages of TEOT hydrolysis ones.
No preview · Article · Aug 2006 · Journal of the American Ceramic Society
[Show abstract][Hide abstract] ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
[Show abstract][Hide abstract] ABSTRACT: The crystallization of anatase titanium dioxide (TiO2) was achieved by a hydrolysis reaction of titanium alkoxide without annealing. The hydrolysis reaction rates of tetraethyl orthotitanate were indicated by a function of the concentration of acetylacetone added. The degree of crystallinity of the product particles was influenced by the amounts of acetylacetone and seed crystals. Anatase TiO2 was crystallized by restraining the rapid increase in supersaturation of TiO2 and the consequent nucleation of amorphous TiO2. The degree of crystallinity of the product particles also changed with the types of seed crystals used, and was strongly influenced by the specific surface areas of the seed crystals.
No preview · Article · Jun 2006 · Journal of the American Ceramic Society
[Show abstract][Hide abstract] ABSTRACT: Two kinds of dispersed nanoparticle photocatalysts of antimonic acid, HSbO3 center dot nH(2)O, namely, SbI and SbII, were prepared separately by the direct reactions of an aqueous H2O2 solution with Sb alkoxide complex, Sb(O-i-C3H7)(3) and metallic Sb powder according to a soft chemical solution process. Their photocatalytic properties were evaluated from methylene blue (MB, C16H18N3SCl) degradation. SbI showed very strong adsorption capability and high photocatalytic activity under UV light irradiation. The average rates of MB degradation were estimated to be 2.403 x 10(-5) M mol h(-1) for Sb1 and 4.01 x 10(-6) M mol h(-1) for SbII. To investigate the reason for their difference in photocatalytic MB degradation, the two Sb-based photocatalysts were characterized by Sb-121 Mossbauer spectroscopy in connection with powder X-ray diffraction and photoabsorption property measurement. The lattice parameters, particle sizes, and relative surface areas were estimated to be 10.372(3) angstrom, 35 nm, and 43.5 m(2) g(-1) for SbI and 10.362(4) angstrom, 70 nm, and 31.4 m(2) g(-1) for SbII, respectively. Valuable information was obtained on valence state and coordination structure of Sb contained in them. These results revealed that SbI had the advantages of high dispersion, fine crystallinity, and large relative surface area as well as only containing the octahedrally coordinated Sb5+ species with d(10) electronic configuration, resulting in having the high photocatalytic activity for MB degradation under UV light irradiation. A small amount of Sb3+ species with d(8) electronic configuration should be considered to be the main reason the photocatalytic performance of SbII for MB degradation was definitely lower than that of SbI.
No preview · Article · May 2006 · Chemistry of Materials
[Show abstract][Hide abstract] ABSTRACT: This paper examines whether a polishing pad with abrasive grain can be adapted for oxide CMP (ILD CMP and STI CMP), which is currently performed by free abrasive polishing. Using the Loosely Held Abrasive (LHA) pad that is effective in the polishing of silicon wafers, silicon oxide and silicon nitride films are polished, and the polishing selectivity and performance are investigated. In the CMP of a silicon oxide film, it is revealed that the removal rate using the combination of the LHA pad and water is 1.6 times more than that using slurry and is compatible in the almost equivalent non-uniformity within a wafer. In free abrasive polishing, the polishing selectivity of a silicon oxide film is 1.4 times that of a silicon nitride film; however, in the case of the LHA pad, it was revealed that the polishing selectivity is 10 times or more. The LHA pad, which is a polishing pad with abrasive grain, can be adapted for ILD CMP and STI CMP, and the polishing selectivity and performance is better than free abrasive polishing.
No preview · Article · Jan 2006 · Journal of the Japan Society for Precision Engineering Contributed Papers