Bio-Medical Materials and Engineering - Volume 19, issue 2-3

Authors: Nikaido, Toru | Weerasinghe, Dinesh D.S. | Waidyasekera, Kanchana | Inoue, Go | Foxton, Richard M. | Tagami, Junji

Article Type: Research Article

Abstract: An acid–base resistant zone (ABRZ) has been shown to be created under a hybrid layer in a self-etching adhesive system at the adhesive/dentin interface. The purpose of this study was to assess the nanostructure of the ABRZ by applying all-in-one adhesive systems. Human premolar dentin was treated with one of two all-in-one adhesive systems; Clearfil Tri-S Bond and G-Bond according to the manufacturers' instructions. After placement of a resin composite, the bonded interface was vertically sectioned and subjected to an acid-base challenge. Following this, the nanostructure of the ABRZ was examined by SEM and TEM. The SEM observations of the …adhesive-dentin interface after the acid-base challenge indicated that a hybrid layer less than 1 μm thick was created, and a ABRZ was formed beneath the hybrid layer for each adhesive system. The TEM observations indicated that the ABRZ contained mineral components in both adhesive systems, however, the thickness of the ABRZ was material dependent. The application of the all-in-one adhesive systems created an ABRZ at the underlying dentin, which reinforced normal dentin against dental caries. Therefore, this zone was named ‘Super Dentin’. Formation of ‘Super Dentin’ is a new approach in caries prevention. Show more

Keywords: Interface, acid–base resistant zone, secondary caries, hybrid layer, all-in-one adhesive system

DOI: 10.3233/BME-2009-0576

Citation: Bio-Medical Materials and Engineering, vol. 19, no. 2-3, pp. 163-171, 2009

Authors: Endo, Kazuhiko | Ohno, Hiroki

Article Type: Research Article

Abstract: Finely powdered enamel was used to develop a prosthetic resin composite that has good mechanical properties and no potential to abrade opposing tooth structure. Bovine teeth were ground into powder and then the enamel particles were separated from the powder by centrifugation in bromoform–ethanol solution. The resin matrix consisted of UDMA (60 mole %) and Tri-EDMA (40 mole %). Camphorquinone (0.5 mass %) was added to the monomer as a photo-initiator. Fillers were incorporated directly into the resin matrix in amounts of 80 or 85 mass %. The flexural strength and Vickers hardness (Hv ) were measured. The average flexural …strength and Hv values for specimens having 85 mass % filler that had been subjected to heat treatment at 100°C after light-curing were 95.2 and 109.8 MPa, respectively, which are higher than those for most commercial prosthetic resin composites. These findings suggest that a novel prosthetic resin composite with good mechanical properties can be made by loading finely powdered enamel into the resin matrix. Show more

Keywords: Enamel powder, prosthetic resin composite, flexural strength

DOI: 10.3233/BME-2009-0577

Citation: Bio-Medical Materials and Engineering, vol. 19, no. 2-3, pp. 173-178, 2009

Authors: Akasaka, Tsukasa | Nakata, Keiko | Uo, Motohiro | Watari, Fumio

Article Type: Research Article

Abstract: Recent studies have shown that carbon nanotubes (CNTs) can be used as biomedical materials because of their unique properties. CNTs effect nucleation of hydroxyapatite, because of which considerable interest has been generated regarding the use of CNTs in dentistry. However, there are only a few reports on the use of CNTs as dental materials. In this study, we investigated the changes induced in the surfaces of tooth slices by the application of a coating of CNTs by observing CNT-coated tooth slices both macroscopically as well as under a scanning electron microscope. Further, we investigated the effect of CNT coating on …the tensile bond strength of dentin adhesives. CNTs adhered easily to the tooth surfaces when tooth slices were suspended in a CNT-dispersed solution. Interestingly, it was observed that CNTs selectively adhered to the surfaces of dentin and cementum, possibly by adhering to their exposed collagen fibers. In addition, the CNT coating did not affect the tensile bond strength of dentin adhesives. These results indicate that coating of the teeth with CNTs can be a possible application of CNTs as dental materials. Show more

Keywords: Carbon nanotubes, coating, tooth slice, dentin, enamel, collagen, tensile bond strength

DOI: 10.3233/BME-2009-0578

Citation: Bio-Medical Materials and Engineering, vol. 19, no. 2-3, pp. 179-185, 2009

Authors: Takada, Tomoya | Furusaki, Atsushi | Tanaka, Yasuaki

Article Type: Research Article

Abstract: The volatile organic compound (VOC) reduction activity of scallop shell powders fired at 300, 600 and 900°C was examined using formaldehyde (HCHO). Raw shells as well as fired shells immediately after firing at several temperatures, except for 600°C, were found to gradually remove HCHO from the air. In the case of shell powders stored for 3 months after firing, the HCHO reduction activity of the powder fired at 900°C was obviously improved, with the HCHO concentrations rapidly reaching zero within 20 min. It has been found by X-ray diffraction measurements that shell powder stored for 3 months after firing at …900°C contains a small amount of calcium hydroxide (Ca(OH)2 ) generated from calcium oxide (CaO). Our results suggest that Ca(OH)2 may be the effective ingredient in the HCHO reduction. Show more

Keywords: Scallop shell, firing, storage, formaldehyde, calcium hydroxide

DOI: 10.3233/BME-2009-0579

Citation: Bio-Medical Materials and Engineering, vol. 19, no. 2-3, pp. 187-192, 2009

Authors: Sultana, Razia | Hamada, Kenichi | Ichikawa, Tetsuo | Asaoka, Kenzo

Article Type: Research Article

Abstract: The purpose of this study was to determine the effects of heat treatment on the bioactivity of hydrothermal-modified titanium in CaO solution for improved bioactivity by immersion in simulated body fluid (SBF). The hydrothermal treatment of titanium in CaO solution was performed at 121°C at 0.2 MPa for 1 h in an autoclave followed by 1 h heat treatments at 200, 400, 600 and 800°C simultaneously. The bioactivity of titanium was evaluated by hydroxyapatite precipitation during immersion in SBF. Surface microstructure changes after the heat treatments and immersion in SBF were determined by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), …and scanning electron microscopy (SEM). Heat treatments at high temperatures (600 and 800°C) promoted the synthesis of anatase, increased the thickness of the titanium oxide layer on the modified titanium surface and promoted the synthesis of calcium titanate, which possibly promoted the precipitation of apatite in SBF. The extent of precipitations increased with the time of immersion in SBF and the temperature of the heat treatment. Island-like deposits of needle-like crystals were observed only on the surface of the 600 and 800°C heat-treated specimens after two or four week immersions in SBF. The results suggested that treatments of the surface of hydrothermal-treated titanium specimens at high temperatures (600 and 800°C) could be effective for the surface modification of titanium as an implant material offering better osseointegration. Show more

Keywords: Titanium, surface modification, heat treatment, hydrothermal treatment

DOI: 10.3233/BME-2008-0580

Citation: Bio-Medical Materials and Engineering, vol. 19, no. 2-3, pp. 193-204, 2009

Authors: Takeuchi, Akari | Munar, Melvin L. | Wakae, Hanae | Maruta, Michito | Matsuya, Shigeki | Tsuru, Kanji | Ishikawa, Kunio

Article Type: Research Article

Abstract: The effect of temperature on crystallinity of carbonate apatite (CAp) foam prepared from α-tricalcium phosphate (α-TCP) foam by hydrothermal treatment was investigated in the present study. The α-TCP foams were prepared through a conventional sintering method using polyurethane foam as template. Then, the resultant α-TCP foams were hydrothermally treated with Na2 CO3 aqueous solution at 100°C, 150°C and 200°C for 72 h. After hydrothermal treatment, the cancellous bone-like macroporous structure of the α-TCP foams was maintained. However, microscopic morphology of the foams' frame significantly changed after the 72 h treatment period. The smooth surface of α-TCP foam disappeared and …the whole surface was covered with plate-like deposits. The plate-like deposits treated at 150°C and 200°C had smooth surface while those treated at 100°C were constructed from spherical particles of approximately 200 nm in diameter. The results of X-ray diffraction and Fourier transform infrared analysis showed that α-TCP was completely converted to CAp and the crystallinity of CAp prepared at 100°C was significantly lower than those prepared at 150°C and 200°C. Hydrothermal treatment of α-TCP foam at 100°C allowed the formation of low-crystalline CAp foam but complete conversion needs a longer treatment period. Show more

Keywords: Carbonate apatite, cancellous bone, ceramic foam, hydrothermal treatment

DOI: 10.3233/BME-2009-0581

Citation: Bio-Medical Materials and Engineering, vol. 19, no. 2-3, pp. 205-211, 2009

Authors: Abe, Shigeaki | Kida, Ikuhiro | Esaki, Mitsue | Akasaka, Tsukasa | Uo, Motohiro | Hosono, Toshiaki | Sato, Yoshinori | Jeyadevan, Balachandran | Kuboki, Yoshinori | Morita, Manabu | Tohji, Kazuyuki | Watari, Fumio

Article Type: Research Article

Abstract: Nano-sized particles have received much attention in view of their varied application in a wide range of fields. For example, magnetite (Fe3 O4 ) nanoparticles have been investigated for various medical applications. In this study, we visualized the distribution of administered magnetic nanoparticles in mice using both X-ray scanning analytical microscopy (XSAM) and magnetic resonance imaging (MRI). After administration, the nanoparticles were rapidly dispersed via the blood circulation, and reached the liver, kidney and spleen. Using the XSAM and MRI methods in a complementary fashion, the biodistribution of nano-sized magnetite particles was successfully visualized.

Keywords: Biodistribution, magnetic resonance imaging, nano magnetite

DOI: 10.3233/BME-2009-0583

Citation: Bio-Medical Materials and Engineering, vol. 19, no. 2-3, pp. 213-220, 2009

Authors: Abe, Shigeaki | Koyama, Chila | Esaki, Mitsue | Akasaka, Tsukasa | Uo, Motohiro | Kuboki, Yoshinori | Morita, Manabu | Watari, Fumio

Article Type: Research Article

Abstract: We observed the internal diffusion behavior of inorganic micro/nano particles through oral administration. By oral exposure, the fed particles were absorbed through the digestive system then reached some organs after internal diffusion in the body. For example, TiO2 particles fed to mice were detected in the lung, liver, and spleen after 10 days of feeding. Whereas, the absorption efficiency was extremely low compared with intravenous injection. In a comparison of the simple amount of administration, oral exposure required 102 times or more amount by intravenous injection for detection by an X-ray scanning analytical microscope. During dental treatment, micro/nano …particles from tooth or dental materials would generate in the oral cavity, and some of the particles had a possibility to be swallowed, absorbed through the digestive system, and then diffuse into the body. However, our results suggest that biocompatible microparticles that are naturally taken orally affect animals only rarely because of the low absorption efficiency. Show more

Keywords: Biodistribution, micro-sized particles, nano-sized particles, oral administration

DOI: 10.3233/BME-2009-0584

Citation: Bio-Medical Materials and Engineering, vol. 19, no. 2-3, pp. 221-229, 2009

Authors: Yada, Keiji | Kohyama, Norihiko

Article Type: Review Article

Abstract: Asbestos minerals are thin fiber type of minerals and honorably said as “the minerals of the miracle” because of their valuable natures even in the strategic field. On the other hand, the relation between asbestos exposure and diseases such as lung cancer and malignant mesothelioma was proved around 1970 by epidemiology and an animal experiment in relation to their microstructures. Here, microstructures of chrysotile asbestos, a mainstream of asbestos substances, are shown. It is also shown that in what kinds of environment people are exposed to asbestos and what kinds of biological or epidemical things happen after asbestos exposure. Many …kinds of fibrous materials as the substitutes of asbestos are described in relation to their carcinogenicity. Show more

Keywords: Structure of asbestos, biological influence of asbestos exposure, asbestos substitutes

DOI: 10.3233/BME-2009-0585

Citation: Bio-Medical Materials and Engineering, vol. 19, no. 2-3, pp. 231-239, 2009

Authors: Kovtun, Anna | Heumann, R. | Epple, Matthias

Article Type: Review Article

Abstract: Transfection is a widely used method in molecular biology for the introduction of foreign nucleic acids (DNA or RNA) into eukaryotic cells that permits to control intracellular processes, i.e. the induction or inhibition of protein expression. Nucleic acids alone cannot penetrate the cell membrane, therefore special carriers like cationic polymers or inorganic nanoparticles are required. Single-shell and multi-shell calcium phosphate nanoparticles were prepared and functionalized with DNA and siRNA. Thereby, the expression of enhanced green fluorescing protein (EGFP) can be induced (by using pcDNA3-EGFP) or silenced (by using siRNA). The single-shell nanoparticles were prepared by rapid mixing of aqueous solutions …of calcium nitrate and diammonium hydrogen phosphate. The multi-shell nanoparticles were produced by adding further layers of calcium phosphate and DNA to protect DNA from the intracellular degradation by endonucleases. The size of the nanoparticles according to dynamic light scattering and electron microscopy was up to 100 nm with a zeta potential around −30 mV. The transfection efficiency of the nanoparticles was tested in vitro in cell culture. Show more

Keywords: Calcium phosphate, nanoparticles, DNA, siRNA, transfection, gene silencing

DOI: 10.3233/BME-2009-0586

Citation: Bio-Medical Materials and Engineering, vol. 19, no. 2-3, pp. 241-247, 2009

Authors: Nagano, Futami | Selimovic, Denis | Noda, Mamoru | Ikeda, Takatsumi | Tanaka, Toru | Miyamoto, Yusei | Koshiro, Ken-ichi | Sano, Hidehiko

Article Type: Review Article

Abstract: Since adhesive technology was introduced into dental field, metal-based restoration has been gradually replaced by metal-free restoration. Using the adhesive technology, minimum invasive technique has been possible in daily clinical practice as well as esthetic tooth-colored restorations have become very popular all over the world. One of the current issues of the dental adhesive is durability of bond between tooth structure and adhesive resin. Several approaches to overcome the issues have been carried out. Self-etching approach is believed to create durable bond because demineralization of superficial tooth surface is very shallow. Other approach is to utilize the inhibitor of …enzymes which are suggested to catalyze the decomposition of resin composites and are always secreted within the oral environment. In the present study, Colloidal Platinum Nanoparticles (CPN) was applied before the application of 4-META/MMA-TBB resin cement as the third possibility to prolong the durability of bond. This implies that the use of the CPN solution would create higher conversion at the interface compared with conventional bonding procedures. Show more

Keywords: Dental adhesive, minimal intervention, durability, colloidal platinum nanoparticles, nano-technology

DOI: 10.3233/BME-2009-0587

Citation: Bio-Medical Materials and Engineering, vol. 19, no. 2-3, pp. 249-257, 2009

Authors: Matsuda, Masami | Hunt, Geoffrey

Article Type: Review Article

Abstract: We initiate some comparisons between Japan, Europe and USA on how far there is governmental support for the ethical, legal, social and environmental dimensions of nanotechnology development. It is evident that in the USA and Europe nanotechnology is now firmly embedded in the consideration of ELSI. Yet Japan has not yet adequately recognized the importance of these dimensions. The history of bioethics in Japan is short. In Europe, as early as 2004, a nanotechnology report by the UK's Royal Society referred to the possibility of some nanotubes and fibres having asbestos-like toxicity. The negative history of asbestos in Europe and …USA is not yet fully identified as a Japanese problem. Japan is therefore in the process of seeking how best to address societal aspects of nanotechnology. Should the precautionary principle be applied to Japan's nanotechnology initiative as in Europe? Should 5–10% of the government's nanotechnology budget be allocated to ELSI research and measures? We propose that the government and industrial sector in Japan play a much more proactive part in the regional and international growth of research into the wider risk assessment, social, health and environmental context of nanotechnologies, not simply try to borrow lessons from the West at a later date. Show more

Keywords: Asbestos, bioethics, ELSI, nanotechnology, USA, Europe, Japan

DOI: 10.3233/BME-2009-0588

Citation: Bio-Medical Materials and Engineering, vol. 19, no. 2-3, pp. 259-267, 2009