The most common side effect of fixed orthodontic treatment is enamel demineraliza-tion or white spot formation around orthodontic brackets. Preventing these lesions is an impor-tant concern for orthodontists because the lesions are unaesthetic, unhealthy and potentially irreversible. Knowledge of adhesion patterns of cariogenic streptococci to orthodon-tic materials can provide valuable information on the cause of enamel demineralization during orthodontic treatment. Streptococcus mutans and Streptococcus sobrinus are the main causative organisms for enamel demineraliza-tion during orthodontic treatment. The adhesion of 2 cariogenic streptococci strains to 11 orthodontic raw materials (5 light-cured orthodontic adhesives, 5 bracket raw materials, and hydroxyapatite) was investigated. The degree of adhesion varied by material type. Each cariogenic streptococci strain showed a characteristic adhesion pattern. The cariogenic streptococci adhered to the glass ionomer significantly more than to the composites, whereas there was no significant difference in the adhesion amount among the four composites. The adhesion amounts were highest in the plastic brackets and lowest in the monocrystalline sapphire brackets. Generally, adhesion of cariogenic streptococci was signifi- cantly higher for bonding adhesives than for bracket materials, and adhesion to resin-modified glass ionomer was the highest. The remaining orthodontic adhesives on the enamel surface provide sites for the rapid attachment and growth of oral microorganisms due to their rough surfaces. Orthodontic bonding adhesives are one of the most potent risk factors for enamel demineralization during orthodontic treatment and clinical observations have indicated that the most common sites for demineralization are at the junctions of the bonding adhesives and the enamel. Bonding adhesives around brackets should be removed carefully during the bonding procedure to avoid enamel decalcification. Cariogenic streptococci can adhere diversely according to adhesive type and that the adhesion of the cariogenic streptococci is not influenced by its fluoride-releasing properties. Incorporation of silver nano-particles into bonding adhesives, however, was successful on both physical and antimicrobial level.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

Optical coherence tomography (OCT) is a non-invasive technique that can produce cross-sectional images of structures in biological systems at a high-resolution. The object of this study was to investigate the ability of OCT system as a nonexcisional cross-sectional imaging modality on adhesive restorations. OCT imaging was performed on to the photo-cured resin composites with internal defects of 0.5 and 0.2 mm in diameter, prepared in several depths. OCT could provide clear cross-sectional images of resin composite and could detect the internal defects at approximately 2 mm in depth.

View full abstract

We try to develop a novel RP ceramic fabrication system which layers alumina and acrylic resin composite slurry and polymerize by UV laser. Fabricated specimens were sintered at the temperature from 1400 to 1700C, and bending strength increased with the sintering temperature. In addition, increase in the bending strength was attempted by the glass infiltration, and effect was noticeable in the case sintered at 1500C. From SEM image it is thought that flaking off between layers generated in the sintering was decreased by the glass infiltration.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

The structure of commercial dental Ag-Pd-Cu-Au casting alloy has been studied by X-ray diffraction analyses after various heart treatments. The composition of phases in equilibrium was established. After being annealed at 1123K for 1h,the alloy of as cast (normal solidification) consisted of three phases;a Cu-and Pd rich fcc phase,Ag-rich matrix,an ordered bcc PdCu,fct PdCu,phases. However,the alloy of liquid rapid solidification is only a phases.No segregation of PdCu phases was detected after solution treatment at 1123K. Why,whether the micro structure of the normal solidification sample often existed of the mixed phase without becoming a single phase in solution annealing heat treatment of 1123K,was examined.

View full abstract

Ti, a Ni-Ti alloy and stainless steel (SUS304) were implanted in rat soft tissues for 6 months. The chemical states of the component elements contained in the tissues surrounding those metallic implants were analyzed by the fluorescence X-ray absorption fine structure (XAFS) method. Titanium oxide and a Ni aquo complex, which would be caused by the erosion of Ti and Ni, were detected in the surrounding tissues. Thus, the dissolved conditions and concentrations of those practical metallic materials in vivo were successfully confirmed.

View full abstract

[in Japanese]

View full abstract

Osteoblasts were cultured in fibrin gel for a long period to fabricate cells, matrix and scaffold composite, which have a potential to reduce the regeneration period of bone. When the composites were implanted in the back of rats, the material promoted the ectopic bone formation compared to those without matrix deposition.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

The 3D cell culture scaffolds derived from the multi-walled carbon nanotubes (MWCNTs) coated collagen sponges was prepared and their cell culturing properties were estimated. The surface and inside of collagen sponge were homogeneously coated with MWCNTs. Saos2 cells were cultured on those MWCNT coated sponge. The inside of the sponge showed good cell adhesion and cell proliferation for Saos2.

View full abstract

[in Japanese]

View full abstract

In order to provide osteoconductivity for bioinert alumina substrate, they were subjected to hydrothermal condition with 10 or 50 mM calcium chloride (CaCl₂) solution at 125^oC for 7 days. Results of in vitro osteoconductivity test using simulated body fluid and rat bone marrow cells indicated that the values of Al₂O₃ substrates treated with CaCl₂ were much higher than that of Al₂O₃ treated without CaCl₂ or non-treated Al₂O₃.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

Amino acids are reported to be effective regulators in HAp formation. We synthesized HAp with basic amino acids (Lysine and Histidine) and characterized the physico-chemical properties of them. FTIR data confirmed that the Lys and His were included in HAp. XRD Data showed that crystallinity of HAp decreased when they were synthesized in presence of Lys and His. These data suggested that the presence of Lys and His during synthesis of hydroxyapatite would regulate its structure and composition.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

In the present study, effect of methodology and specimen thickness on the flexure strength of yttria stabilized tetragonal zirconia polycrystals and the zirconia/alumina nanocomposite stabilized with cerium oxide was evaluated through the biaxial, the 3-point and 4-point flexure strength test.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

Composite resin has the virtue of excellent color and gloss. However, it is supposed that surface roughness by polishing can influence the color and gloss, and the degree of the influence might differ among regular, opaque and transparent shades. Resin disks of 2 mm in thickness and final polish with 180, 1000 or 3000-grit silicon carbide papers were made by submicron filled composite Estelite Sigma Quick (shades: A2, OA2, Incisal). Influence of surface roughness to color and gloss was compared among shades.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

Plates of experimental Ti-Ag alloys, pure titanium, pure silver, and an Au-Ag-Pd alloy were prepared. Streptococcus mutans was cultured anaerobically in a complex culture medium containing 0.5% sucrose in the presence of each plate sterilized. The amounts of biofilm formed on the plates were estimated by optical density. In addition, the bactericidal activity of these plates was evaluated.

View full abstract

[in Japanese]

View full abstract

We examined the chemical interaction of functional phosphoric asid monomers (10-MDP, phenyl-P) and a hydroxyapatite (HAp) particle used for XRD and solid-state NMR. The monomer 10-MDP, which has better long-term durability, formed the layered structure of MDP-Ca salt on the HAp surface in early period. On the contrary, when phenyl-P interacted with HAp, DCPD was formed by decalcification of HAp but phenyl-P-Ca salt was not formed.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

Possible carrying ozone disinfection vessel ( the 29.7L content volume ) for the medical device was produced experimentally, and the sterilization test was carried out. In case of Candida albicans as the result , though in all sterilization process 10 minutes(the ozone evolution hour : 6 minutes ), the fungus did not die out for 100000 fungi a little, in all sterilization process 20 minutes(the ozone evolution hour : 12 minutes ),, the fungus perfectly died out. However, several fungi did not die out even in all sterilization process 10 minutes and for 20 minutes for 100000 fungi in case of Bacillus subtilis subsp. Subtilis. Then, sterilization effects, etc. are reported, because the high-speed ordinary-temperature ozone disinfection vessel ( about 7L content volume ) in which portable type of content volume of produced ozone disinfection vessel of about 1/4 was possible in respect of the last time was newly manufactured and was examined.

View full abstract

[in Japanese]

View full abstract

An optical profile machining for a 3D free-formed surface with an under cut portion has been developed by using an optical measuring system and NC machining, which these is constructed by 5-axis control system. Then, it was attempted to machine for a crown with an overhang portion by using this developed this system. As a result, it was verified that this developed system is capable of measuring a 3D free-formed shape and of machining it accurately.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

This research forcusd on the reinforcement of resin based composite for prosthetic treatement.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract