Biomedical subjects

M Atsuta

Publications and source records attributed to M Atsuta.

At least 19 recordsLinked to original sources

PubMed1995

Effect of two metal primers on adhesive bonding with type IV gold alloys.

Bond strengths of an adhesive resin bonded to two types of gold alloys were investigated in vitro with two different metal primers. Disk specimens were cast in a type IV gold alloy designed for resin-bonded restorations and in a low-temperature age-hardenable gold alloy. The specimens were primed with either a vinyl-thiol primer or a thiophosphate primer, then bonded with an adhesive resin initiated with tri-n-butyl borane derivative. Both primers effectively enhanced bond between gold alloys and the adhesive. The use of metal primers in conjunction with type IV gold alloys is useful for resin-bonded fixed partial dentures.

Acrylic Resins↗

PubMed1995

Effect of unfilled resins and a silane primer on bonding between layers of a light-activated composite resin veneering material.

This investigation evaluated the effect of unfilled resins and a silane primer on bonding between layers of a urethane-based composite resin veneering material. Shear bond strengths between the layers were determined with a two-liquid silane primer and three unfilled resin bonding agents. The silane primers and unfilled resins enhanced the bond between layers of the veneering material. Durability of the bond, however, was influenced by the composition of the bonding agent. Among the systems investigated, combined use of the silane primer with triethyleneglycol dimethacrylate-based unfilled resin exhibited durable and consistent bond strength.

Analysis of Variance↗

PubMed1995

Diverse expression of beta 1,4-N-acetylgalactosaminyltransferase gene in the adult mouse brain.

Among various tissues of mouse, beta 1,4-N-acetylgalactosaminyltransferase (GM2/GD2 synthase) gene is expressed predominantly in the brain. Further analysis of the gene expression in the mouse CNS was performed by northern blotting and by enzyme assays using extracts from various parts of the CNS. In situ hybridization was also done to investigate the distribution of cells generating GM2/GD2 synthase. In northern blots, diverse levels of the gene expression were observed, depending on the regions examined. By in situ hybridization, pyramidal cells in the hippocampus, granular cells in dentate gyrus and cerebral cortex, Purkinje cells in cerebellum, and mitral cells in the olfactory bulb expressed high levels of the mRNA; these results corresponded to the results obtained by northern blot. Enzyme levels in these sites were accordingly high. However, enzyme levels in certain areas with low mRNA intensities, such as thalamus and pons medulla, were higher than expected from the results of northern blotting. The significance of the high gene expression in certain areas for brain function and the reason for the discrepancy between mRNA level and enzyme activity in some regions are discussed.

Animals↗

PubMed1995

Adhesive bonding of titanium with a methacrylate-phosphate primer and self-curing adhesive resins.

The adhesive bonding of titanium was evaluated with the use of a metal primer and three types of self-curing luting agent. The primer contained 10-methacryloyloxydecyl dihydrogen phosphate (MDP). One luting agent was a composite material that contained the MDP monomer in its liquid part. The other luting agent was based on methyl methacrylate (MMA), initiated with tri-n-butylborane derivative (TBB), and contained 4-methacryloxyethyl trimellitate anhydride (4-META). The MMA-TBB resin without 4-META was used for the control. Pure titanium metal specimens were bonded with various combinations. Shear bond strengths were determined after repeated thermocycles in water. Both MDP and 4-META were effective in bonding titanium. The decrease in bond strength was minimum when the titanium was primed with MDP and then bonded with the TBB-initiated resins.

Acrylic Resins↗

PubMed1994

Dimensional changes related to ordering in an AuCu-3wt%Ga alloy at intraoral temperature.

OBJECTIVES: The purpose of this study was to evaluate the distortion behavior of a gold alloy with age-hardening ability at intraoral temperature induced by phase transformations. METHODS: Bridge-type specimens were prepared using AuCu-3wt%Ga alloy with age-hardening ability at 37 degrees C. Dimensional changes, hardness and surface roughness were measured. Transmission electron microscopy observation was carried out using AuCu-3wt%Ga discs aged at 37 degrees C for 30 d. RESULTS: Hardening was brought about rapidly in the initial stage of aging at 37 degrees C owing to ordering. The ordering was attributed to the formation of AuCu I and AuCu II superlattices. A linear contraction of 0.04% was induced by aging at 37 degrees C for 3 d. Distortion of the bridge-type specimen was brought about by a combination of linear contractions. The surface roughness increased in the initial stage of aging due to the surface relief effect of internal coherency strain caused by tetragonality. SIGNIFICANCE: The mode of distortion may be more advantageous for use in crown-type rather than inlay-type restorations, and the amount of contraction may not produce any problems in clinical use.

Chemical Phenomena↗

PubMed1992

Restricted expression of recombination activating gene (RAG-1) in mouse lymphoid tissues.

In an attempt to determine the distribution of recombinase activity in the mouse thymus, spleen and lymph nodes, we used the in situ hybridization method to examine the expression of the recombination activating genes RAG-1 and RAG-2. Expression of RAG-1 was found in most cortical thymocytes but not in the majority of medullary thymocytes. Although hybridization signals of RAG-2 were not as intense as those of RAG-1, the localization of RAG-2 transcripts was similar to that of RAG-1. In the spleen, expression of RAG-1 was found only in limited cells near the sinus, and the majority of the cells within the follicle were negative for RAG-1 transcript. In nude mice, RAG-1-expressing cells were detected in the same regions, which suggests that in situ hybridization signals of RAG-1 in the spleen are due to the cells of B cell origin. In the lymph nodes, expression of RAG-1 was found only in the medullary region. Expression of RAG-2 transcript in the spleen and the lymph nodes, if any, was too faint to determine the specific localization. These results suggest that most of the cortical thymocytes and some cells in the spleen are capable of rearranging T cell receptor genes and immunoglobulin genes, respectively, but the possibility of some other explanation could not be ruled out in RAG-1 expressing cells of the spleen and the lymph nodes.

Animals↗

PubMed1992

Bonding fixed prosthodontic composite resin and precious metal alloys with the use of a vinyl-thiol primer and an adhesive opaque resin.

Adhesive bonding of a light-cured fixed prosthodontic composite resin joined to silver- and gold-based alloys was investigated with the use of a metal primer and an adhesive opaque resin. The primer contained an adhesive bonding promoter for precious alloys, 6- (4-vinylbenzyl-n-propyl) amino-1, 3, 5-triazine-2, 4-dithiol (VBATDT). The cast metal specimens were alumina-blasted and primed with VBATDT acetone solution. A self-curable 4-META/MMA-TBB opaque resin was used to bond the primed metals and a light-cured composite resin. Prepared specimens were thermocycled in water and bond strengths were determined. The shear bond strengths after 100,000 thermocycles (4 degrees C to 60 degrees C for 1 minute) were 28.4 MPa for Ag-Pd-Cu-Au alloy and 20.8 MPa for type III gold alloy. This simple method may be used to bond silver or gold alloy and light-activated fixed prosthodontic composite resin.

Adhesives↗

PubMed1992

The relationship between monomer composition and physical properties of light-cured opaque resin.

Light-cured opaque resins were prepared using four types of monomer liquids and titanium dioxide powder. This study investigated the relationship between the monomer composition and the physical properties of light-cured opaque resin. Depth of cure, KHN, residual monomer eluent, and bond strength between the opaque resin and cobalt-chromium alloy were measured. The physical properties of triethyleneglycol dimethacrylate (TEGDMA)-based compositions were superior to those of methyl methacrylate (MMA)-based compositions. Viscosity of the opaque resin's liquid monomer was enhanced by 1,6-bis(methacryloxy-2-ethoxycarbonylamino)-2,4,4-trimeth ylhexane (UDMA). The TEGDMA-based light-cured opaque resins showed excellent physical properties and may be clinically acceptable in bonding prosthodontic composite to metal frameworks.

Acrylic Resins↗

PubMed1992

Radiopacity and physical properties of titanium-polymethacrylate composite.

Titanium-polymethacrylate composite was prepared as an x-ray-opaque filler for composite core materials. The base monomers of the composite were 2,2-bis [4-(3-methacryloyloxy-2-hydroxypropoxy) phenyl] propane (Bis-GMA) and triethyleneglycol dimethacrylate (TEGDMA). Pure titanium powder was used as a radiopaque element. Two functional methacrylates--isopropyl dimethacryloyl isostearoyl titanate (KR-7) and 4-methacryloyloxyethyl trimellitate anhydride (4-META)--were adopted as couplers of titanium powder. The radiopacity of composites was determined in terms of their equivalent thickness of aluminum per unit thickness of material. Compressive and transverse strengths of the composites were measured by use of coupled and untreated titanium fillers. The composites that contained 70% and 80% titanium by weight showed more radiopacity than enamel and less than amalgam. Radiopacity was controlled by the content of titanium filler in the composite. The decrease in compressive and transverse strengths of the composites was 0.7 to 15.9% and 43.7 to 52.9%, respectively, after one year's immersion in water. The decrease in transverse strength was remarkable; however, this deterioration was diminished by use of both KR-7 and 4-META as couplers for titanium. Thus, prepared titanium-polymethacrylate composite may be used as a radiopaque composite filler for self-curing composite core materials.

Composite Resins↗

PubMed1991

Surface preparations for metal frameworks of composite resin veneered prostheses made with an adhesive opaque resin.

Bond strengths of a laboratory developed light-cured composite resin to dental casting alloys were evaluated with a new adhesive opaque resin. The metal specimens were type III gold, nickel-chromium, and cobalt-chromium alloys, while the surface treatments for bonding were heating, Sn plating, and ion coating. The cast metal specimens were "particle blasted" with aluminum oxide and were surface treated. Adhesive 4-META/MMA-TBB opaque resin was applied and a light-cured composite resin was placed over the opaque layer. The prepared specimens were thermocycled in water and shear bond strengths were recorded. The light-cured composite resin was bonded strongly to heated or Sn-plated type III alloy with 4-META/MMA-TBB opaque resin. Copper ion coating in a sputter coater was effective for all three alloys, with only slightly diminished bond strengths. These methods were satisfactory for making composite resin veneered prostheses.

Acrylic Resins↗

PubMed1990

Monomer composition and bond strength of light-cured 4-META opaque resin.

A light-cured opaque resin was prepared with 4-(2-methacryloxyethoxycarbonyl) phthalic anhydride (4-META), bifunctional methacrylates, and titanium dioxide (TiO2). The relation between monomer composition and bond strength was examined with seven methacrylate monomers. Methyl methacrylate (MMA) was useful as a solvent of 4-META. However, it was not sufficiently cured by photo-initiator. The bond strength of a triethyleneglycol dimethacrylate (TEGDMA)-based composition was superior to other monomer-based compositions after repeated thermocycles. 1,6-bis(methacryloxy-2-ethoxycarbonyl-amino)-2,4,4-trimethylhex ane (UDMA) effectively provided viscosity to the composition. The prepared opaque resin consisted of 4-META/MMA-TEGDMA primer, TEGDMA-UDMA-based monomer, and titanium dioxide. This opaque resin bonded strongly to alumina-blasted cobalt-chromium alloy. The light-cured 4-META opaque resin may be useful for bonding prosthodontic composite to metal frameworks.

Acrylic Resins↗

PubMed1990

Adhesive bonding of titanium with a titanate coupler and 4-META/MMA-TBB opaque resin.

Adhesive bonding of titanium was evaluated with a titanate primer and adhesive opaque resin. The primer consisted of 2% isopropyl dimethacryloyl isostearoyl titanate in methyl methacrylate. The adhesive was 4-META/MMA-TBB opaque resin that contained 4-methacryloyloxyethyl trimellitate anhydride and was initiated by tri-n-butylborane derivative. Titanium discs were machined and blasted with aluminum oxide. They were primed and bonded together with the opaque resin. A shear test was performed after repeated thermocycles for investigation of the durability of the bond. The shear strength of the primed and 4-META resin-bonded specimens was 37.2 MPa after 50,000 thermocycles, with only a small decrease in bond strength. This was significantly higher than the control values. Thus, titanate primer and 4-META/MMA-TBB opaque resin may be used for the bonding of titanium in prosthodontic practice.

Acrylates↗

PubMed1990

[Micro powder retention for retaining acrylic resin veneers. 1. Application of pressure sensitive adhesive].

Powder retentions are widely used in clinical for retaining acrylic resin facing of veneered crown. These retentions show relatively high bond strength and easy manipulation compared with the traditional retention devices of bar, hole, bead, loop and etc. However, the particle size of powders commercially available are above 250 microns and reduced the thickness of facing resin. Thereupon, smaller diameter of powder were trially applied, however, microparticles were submerged under adhesive and undercut effective for retaining resin was lost. In this research, a new powder retention system adopted pressure sensitive adhesive was studied. The trial adhesive includes volatile solvent like as the traditional adhesives. However, the solvent vapors rapidly and the adhesive applied onto the wax pattern showed pressure sensitivity. Six different sizes of spherical powder were used and the smallest and largest particle size were 90-110 microns and 230-250 microns respectively. New powder retention system applied sensitive adhesive exhibited excellent bond strength to photo polimerized composite facing resin and denture base resin. The powder of 110-130 microns diameter showed shear bond strength values of above 200 kgf/cm2 after 30,000 thermocycles.

Acrylic Resins↗

PubMed1990

[A light-cured acrylic adhesive for fixing resin retention devices to the wax pattern].

A light-cured acrylic adhesive for fixing resin retention devices to the wax pattern was prepared. The adhesive consisted of trimethylolpropane triacrylate, 2-ethylhexyl acrylate, benzoin methyl ether, p dimethylaminobenzaldehyde and p-methoxyphenol. The adhesive could be cured within 20 sec not only by an UV photo curing unit but by a visible-light source with a xenon lamp. The adhesive and retention beads burned out after about an hour in the electric furnace at 400 c. The metal specimens with retention devices were cast in Ag-Pd-Cu-Au alloy with the use of two types of retention beads adhesive. The light-cured adhesive was superior to the conventional one in handling and some other properties. This adhesive may be used to fabricate composite veneered prostheses with minimum errors in laboratory procedure.

Acrylates↗

PubMed1990

[Physical properties of light-cured opaque resin. (1) Influence of monomer composition].

Light-cured opaque resins with excellent physical properties were prepared using five types of monomer liquid and titanium dioxide as the powder. The five opaque resin monomer liquid had the following monomer compositions. Methyl methacrylate (MMA)/di(methacryloxyethyl) trimethylhexamethylene diurethane (UDMA) = 70/30 (M-U), MMA/neopenthylglycol dimethacrylate (NPG)/UDMA = 45/45/10 (M-N-U), UDMA/MMA = 70/30 (U-M), 2,2-bis (4-methacryloxypolyethoxy phenyl) propane (2.6 E)/2,2-bis [4-(3-methacryloxy-2-hydroxy propoxy) phenyl] propane (Bis-GMA)/triethyleneglycol dimethacrylate (3 G) = 60/35/5(2.6-B-3) and 3 G/UDMA = 70/30 (3-U) by weight. The bond strength, photo-curability and handling properties of the opaque resin were improved. Three MMA-based opaque resins showed nearly the same values in Knoop hardness number, diametral tensile strength and shear bond strength. The depth of cure increased with the decrease in MMA content of monomer composition, while the amount of residual monomer decreased. The 2.6-B-3 opaque resin had nearly the same properties in depth of cure and Knoop hardness number as the 3-U opaque resin. However, the 2.6-B-3 and 3-U opaque resins had a diametral tensile strength more than twice as high as that of the U-M opaque resin. The bond strength of three MMA-based opaque resins showed 0MPa after 5,000 thermocycles, while the 2.6-B-3 opaque resin, about 16 MPa, and the 3-U opaque resin, about 25 MPa. Therefore, the bond strength of the opaque resin was influenced by monomer composition. 3G-UDMA opaque resin showed excellent physical properties and may be clinically acceptable to bond fixed prosthodontic composite.

Bisphenol A-Glycidyl Methacrylate↗

PubMed1989

A new porcelain repair system with a silane coupler, ferric chloride, and adhesive opaque resin.

A new porcelain repair system was developed which uses a two-liquid primer, self-cured opaque resin, and light-cured composite. The primer consisted of two liquids. One component was 4% 3-trimethoxysilylpropyl methacrylate in methyl methacrylate, and the other component was 0.5% ferric chloride in ethanol. A self-curing opaque resin, 4-META/MMA-TBB opaque resin, was used as an adhesive to bind the porcelain and the composite. Adhesive opaque resin was applied on the roughened and primed porcelain. Light-cured composite was placed over the 4-META opaque layer. A shear test was performed for investigation of the strength and durability of the bonding. The result was that for all specimens after 20,000 thermocycles, fracture or crack propagation during the shear test occurred in the porcelain, rather than in the bond. This system may be used to repair fractured porcelain facings without removal of prostheses.

Acrylic Resins↗

PubMed1989

[Bonding durability of various adhesion systems of dental alloy in aciditic solution].

Previous studies found that the adhesive resin provided strong adhesion to alloys. Also, the bond durability was improved by oxidation of alloys. In oral, many aciditic substances exist. However, the oxides yielded by oxidation are unstable in aciditic environment. Thereupon, the adhesive resin systems should be studied in aciditic environment. In this study, half of the alloy disks were air-brushed with alumina and the remaining half were polished with #600 emery. They were then ion-coated. One third of the disks were with Cu oxide another one third were Cu.Sn oxide, and remaining were Sn oxide. The handle was affixed by the 4-META resin. For reference, Co-Cr specimen oxidized ultrasonically was fabricated. Completed specimens emery polished were stored in lactic acid at 37 degrees C for 3 months, and sand-blasted were for 6 months. Then the tensile strength was measured. In 0.002% solution, initial bond strength of all the specimens was maintained after immersion. After 1.0% immersion, bond strength of Cu oxide coating specimen polished with emery decreased rapidly. Bond strength of Cu.Sn oxide and Sn oxide coated specimens decreased slowly. Sand-blasted specimens showed higher durability than emery polished. Co-Cr alloy specimen showed the highest durability, and 260 kgf/cm2 was maintained after 6 months in 2.0%.

Dental Alloys↗

PubMed1989

[Study on ion-coating surface treatment of dental alloys for adhesion. 2. Effect of Sn and Cu-Sn target on Au-Ag-Pd alloy].

Previous study found that ion coating treatment with Cu target demanded 10 minutes of treatment to achieve the durable adhesion with 4-META resin. For clinical application, it's indispensable to shorten the treatment period. Sn and Cu-Sn target were examined in this study. 4 minutes of treatment with Sn target showed high bond strength of adhesion. However, the excess of treatment time over 8 minutes caused the remarkable decrease of adhesion durability against thermal cycling. In clinical situation, many of the prosthesis possess the wings of complex shape and it's difficult to attain the uniform coating by only once treatment. However, the repetition of treatment with Sn target is undesirable because of the decrease of adhesion durability. Favorable result was shown by 4 minutes of treatment with Cu-Sn target and even by 30 minutes of treatment, same result was attained. With this ion treated specimens of Au-Ag-Pd alloy sandblasted, the adhesive bond strength of above 200 kgf/cm2 was maintained after 100,000 thermocycles.

Acrylic Resins↗