[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 METHODS: Test 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. RESULTS: Fluoridated 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 360 h 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.
[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.
Journal of prosthodontic research. 10/2010; 54(4):185-91.
[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.
Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology - PRECIS ENG. 01/2009; 33(2):167-174.
[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.
Ceramics International - CERAM INT. 01/2008; 34(7):1637-1642.
[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.
Journal of Coatings Technology and Research 01/2007; 4(3):327-333. · 1.09 Impact Factor
[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.
Journal of the American Ceramic Society 08/2006; 89(9):2782 - 2786. · 2.11 Impact Factor
[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.
Journal of the American Ceramic Society 06/2006; 89(8):2381 - 2386. · 2.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Hydroxyapatite (HAp) was crystallized on anatase titanium dioxide (TiO2) photocatalytic crystals or their thin films using of a pseudo-body solution method, and electrochemical properties of the HAp-adhered anatase TiO2 photocatalytic surfaces were discussed. Decomposition rates of methylene blue were faster for the HAp-adhered anatase TiO2 photocatalysts, although specific surface areas were smaller than those for the commercial anatase TiO2 ones. Surface potential dispersions on the HAp-adhered anatase TiO2 thin films before and after an ultraviolet light irradiation were measured by an atomic force microscopy. Changes in the color of leucocrystalviolet mixed in the HAp-adhered anatase TiO2 photocatalysts or the commercial anatase TiO2 ones with experimental durations were compared. Movements of electrons from the anatase TiO2 photocatalytic surfaces to the HAp, crystals and oxidizing reactions on the HAp-adhered anatase TiO2 photocatalytic surfaces in the dark were discussed on the basis of these experimental results.
Journal of the American Ceramic Society 12/2005; 89(3):944 - 948. · 2.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Titanium dioxide coated with apatite (AP-TiO2) was produced by stirring commercial TiO2 (ST-01) into a simulated body fluid (SBF). Radicals generated at the surface of photoaccelerated ST-01 and AP-TiO2 were analyzed by electron spin resonance (ESR) spectroscopy in a spin-trapping experiment. During photoirradiation for 0-60 s, photogenerated [DMPO-OH] for ST-01 and AP-TiO2 increased with irradiation time. On the other hand, during photoirradiation for 60-500 s, [DMPO-OH] for ST-01 decreased but [DMPO-OH] for AP-TiO2 did not. On the basis of these phenomena, it was suggested that DMPO trapped photogenerated OH• and was converted into DMPO-OH which then decomposed to H2O2 upon further photoirradiation. The decomposition of DMPO-OH and generation of H2O2 were prevented by apatite at the surface of TiO2. Additionally, the adsorptive nature of AP-TiO2 for methylene blue and photocatalytic activity for bleaching were improved by apatite at the surface of TiO2.
Japanese Journal of Applied Physics 01/2005; 44:5164-5170. · 1.07 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: For uniformly implanting hydroxyapatite (HA) granules into curved surfaces of titanium alloy implants such as dental roots, a new superplastic forming system was developed. By fixing PVA films with HA granules on a die's curved inner surface, HA granules are uniformly scattered and hold on the surface. The pressing system has a couple of wedges that enable press load to act on the both sides of a cylindrical titanium alloy sample arranged with its long axis perpendicular to the direction of the load in the die, and thereby the sample to expand in its radius direction. This technique could uniformly press HA granules into all the curved surface of titanium alloy. As a result, HA-granule-implanted titanium alloy composites with a cylindrical shape were formed under the conditions of 1023 K, 1 h, 1960 N in vacuo.
Journal of Materials Science Materials in Medicine 03/2002; 13(2):233-6. · 2.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In order to improve the biocompatibility of superplastic Ti-alloys such as Ti–6Al–4V or Ti–4.5Al–3V–2Fe–2Mo, coating of the alloy with pure titanium and TiO films by magnetron DC sputtering was examined. The sputter-deposition of the pure titanium film and the TiO films were carried out in Ar gas and in ArO2 gas mixtures, respectively. Both the pure titanium film deposited in Ar and the TiO films deposited in ArO2 appeared to be uniform and adhesive. Under AES, the Ti/O ratio in depth direction was nearly constant in each of the films and oxygen concentration increased with increasing oxygen content of the sputter gas. Based on XRD, it was concluded that oxygen atoms dissolved into α-titanium crystals at lower oxygen contents, while suboxides such as Ti4O7 and Ti6O11 and oxides such as TiO2(anatase) were formed at higher oxygen contents. It was found that the orientation of the α-titanium phase formed in the TiO films changed from (002) dominant to (011) dominant with increasing oxygen content. The Vickers hardness of the films increased linearly with increasing oxygen content, and the maximum hardness reached over Hv=1600. Furthermore, it was found that the ductility of the deposited pure titanium film was improved under such high temperatures as 800°C and that its elongation reached over 160%, while the TiO films were still brittle under such a high temperature.
Thin Solid Films 05/2001; 386(2):227–232. · 1.87 Impact Factor