Biomedical subjects

S Wakumoto

Publications and source records attributed to S Wakumoto.

At least 19 recordsLinked to original sources

PubMed1992

Laser-Raman spectroscopic study of the adhesive interface; analysis between 4-META/MMA-TBB resin and bovine or human dentin.

A study of the adhesive interface between 4-MET/MMA-TBB resin and hydroxyapatite or bovine enamel was reported. The present report is a continuation of that study. The possible chemical interaction between 4-methacryloxyethyl trimellitic acid (4-MET) and bovine or human dentin was examined by laser Raman spectroscopy. A 4-MET monomer solution was prepared by evaporating two thirds of the methyl methacrylate (MMA) in a commercial dentin adhesive. The solution was then applied to a dentin surface after treating the surface with an aqueous solution of 10% citric acid containing 3% ferric chloride. A salt formed on both bovine and human dentin surfaces. This salt was formed by the process we previously reported in which 4-MET formed a salt on the hydroxyapatite and bovine enamel. No evidence was observed of chemical reaction between 4-MET and any organic component in the dentin.

Acrylic Resins↗

PubMed1992

Possibility of allergic reaction to dentin primer--application on the skin of guinea pigs.

We studied the allergic reaction of guinea pigs to glyceryl methacrylate (GM), hydroxyethyl methacrylate (HEMA) and meso-erythritol methacrylate (EM), which are used as dentin primers. On the 18th day of the application test, when macroscopic investigation revealed an inflammatory reaction, the methacrylic acid-treated group showed marked eschar formation in comparison with the control group. In each of the dentin primer groups, a slight degree of skin redness was noted, but there were no serious symptoms. On the 25th day, the applications were resumed macroscopic inspection on the 32nd day found eschar in the methacrylic acid group only. Therefore, this experiment with dentin primers suggests a delayed allergic reaction. Local irritability test showed a more severe reaction than the application test. In this test, all experimental dentin primers and methacrylic solution promptly showed inflammation, and the chemical compound, methacrylic acid was a factor in inflammation.

Animals↗

PubMed1991

The optimum combination of dentin bonding systems.

The efficacy of dentin bonding systems composed of a commercial or an experimental dentin cleanser, a dentin primer, and an intermediate resin was examined by measurement of the wall-to-wall polymerization contraction gap. Light-activated composites in a cylindrical dentin cavity were prepared in exposed dentin of the proximal surface of the extracted human premolar. The combination of a dentin cleanser of neutralized 0.5 mol/L EDTA, a dentin primer of 35% hydroxyethyl methacrylate (HEMA) or 35% HEMA containing 5% glutaraldehyde and a commercial intermediate resin (Clearfil New Bond, Kuraray Co., Osaka, Japan; Pyrofil Light Bond, Sankin Co., Osaka, Japan) was effective in compensating for the contraction stress of a light-activated composite and for obtaining marginal integrity between the composite and the dentin cavity wall.

Composite Resins↗

PubMed1991

The effects of primers on the sensitivity of dentin.

The effects of dentin primers on the sensitivity of dentin were examined by measurement of the repetitive firing observed when a class V cavity prepared in the dentin of the lower jaw of a rabbit was irritated by a blast of compressed air. It was possible to conclude that the combined application of an aqueous solution of 35% hydroxyethyl methacrylate and a commercially available dentin bonding agent was effective for reducing the repetitive firing and for maintaining such a "sedative " effect. Although the dentin tubules were sealed mechanically by the resin material, it was impossible to explain the mechanism by which the dentin primer application reduced firing.

Aminosalicylic Acids↗

PubMed1991

Marginal adaptation of nine commercial intermediate resins.

The bonding efficacy of nine commercially available intermediate resins was examined by measuring the maximum contraction gap of a light-activated composite in a cylindrical cavity of human dentin. With only one exception, the marginal adaptation of the composite improved significantly when the intermediate resins were combined with an experimental dentin cleaning system of the neutralized 0.5 mol/L EDTA and a dentin primer composed of a 35% aqueous solution of either hydroxyethyl methacrylate (HEMA) or glyceryl methacrylate (GM). Complete marginal adaptation was obtained with four tested materials when dentin was pre-treated with EDTA and GM.

Analysis of Variance↗

PubMed1991

Vibrational analysis by Raman spectroscopy of the interface between dental adhesive resin and dentin.

The Raman microprobe technique was applied for analysis of the molecular components at the adhesive interface between 4-META/MMA-TBB resin and dentin. The Raman spectra showed that the 4-META molecules in monomer solution were mostly hydrolyzed into 4-MET molecules, which were then co-polymerized with MMA molecules to form resin and resin-reinforced dentin layers. On the basis of line analysis by the Raman microprobe, resin molecules were estimated to penetrate 6 microns into the dentin from the interface. Raman intensity studies indicated that the concentration of 4-MET molecular units in the resin-reinforced dentin was more than four times the concentration in the original monomer solution. This demonstrated the excellent infiltration ability of 4-MET monomer into dentin substrate in situ.

Adhesives↗

PubMed1991

Bonding efficacy of erythritol methacrylate solutions as dentin primers.

The bonding efficacy of aqueous solutions of two kinds of erythritol methacrylates as dentin primers was examined by measurement of the polymerization contraction gap of a light-activated resin composite in a cylindrical dentin cavity and the tensile bond strength of the composite to the flat dentin surface. The dentin surface was cleaned with neutralized 0.5 mol/L EDTA and pre-treated with a meso-erythritol or penta-erythritol methacrylate solution, followed by application of a commercial dentin bonding agent (Clearfil New Bond) and a resin composite. Among the tested primers, a 40% meso-erythritol methacrylate solution was shown to be the most effective because, in contrast to the other primers, contraction gap formation by the composite was prevented in all tested specimens.

Composite Resins↗

PubMed1991

Laser-Raman Spectroscopic study of the adhesive interface between 4-MET/MMA-TBB resin and hydroxyapatite or bovine enamel.

The possible chemical interaction between synthetic hydroxyapatite or bovine enamel and a functional monomer of 4-methacryloxyethyl trimellitic acid (4-MET) diluted in methyl methacrylate (MMA) was examined by measuring the Raman spectra. It was concluded that the carboxyl group of 4-MET reacted with the calcium in the substrate to form a salt that was detected by the Raman band at around 1,380 cm-1. However, formation of the salt on the surface of the hydroxyapatite (HAP) with the carboxyl group, and polymerization of the 4-MET in the methacryl group near the surface were mutually exclusive reactions for the same 4-MET molecule.

Adhesives↗

PubMed1990

Effect of water sorption and thermal stress on cavity adaptation of dental composites.

The effect of water sorption of composite and thermal stress on the marginal adaptation to the dentin cavity wall was evaluated by measurement of the gap width between composite fillings and the dentin cavity wall. The wall of a cylindrical dentin cavity prepared in the proximal surface of extracted human molars was cleaned with neutralized 0.5 M EDTA and pre-treated with one of three experimental dentin primers [35% hydroxyethyl methacrylate (HEMA), 35% HEMA containing 5% glutaraldehyde, and 35% glyceryl methacrylate]. A light-activated composite (Silux, 3M Co., St. Paul, MN) was used to fill the cavity after application of a bonding agent (Clearfil New Bond, Kuraray Co., Osaka, Japan). The marginal gap width was measured after the specimens were immersed in water and thermal-cycled. The initial contraction gap of the tested bonding systems was closed completely by the water sorption of the composite for six hours, and such a marginal adaptation was not interrupted by 60 thermal cycles between 10 and 45 degrees C. Among the dentin primers tested, only the 35% aqueous solution of glyceryl methacrylate mediated gap-free fillings in all specimens.

Composite Resins↗

PubMed1990

Morphological changes of rabbit skin by application of dentin primer.

The side effects of dentin primer applications on soft tissue were examined pathologically. Of the 4 experimental dentin primers tested, dimethylaminoethyl methacrylate (DMAEM) and glutaraldehyde (GLU) caused irritation to the skin of rabbits whereas hydroxyethyl methacrylate (HEMA) and glyceryl methacrylate (GM) caused only insignificant changes in the substrate. It was concluded that an aqueous solution of GM can be used clinically because of its low irritation to skin and high bonding efficacy, as previously reported, though possible irritation to pulp tissues should perhaps still be investigated. The mechanisms of irritation to operator fingertips caused by repeated direct contact with dentin primers containing HEMA remain unknown.

Animals↗

PubMed1990

Clinical evaluation of the sedative effect of HEMA solution on the hypersensitivity of dentin.

The sedative effect of the dentin primer, 35% hydroxyethyl methacrylate (HEMA) solution, on dentin hypersensitivity was clinically evaluated. Exposed root surfaces of teeth were cleaned with neutralized 0.5 mol/L EDTA and treated with 35% HEMA solution followed by the application of a commercial dentin bonding agent. The extent of sedation was estimated by comparison of the responses before and after treatment to irritation by a cold water spray, compressed air blast and scratching with an explorer. The degree of the response to these irritations was decreased significantly upon the combined application of HEMA and commercially available dentin bonding agents though it was still ineffective in nearly 30% of the 48 cases tested.

Composite Resins↗

PubMed1990

[Adaptability of composite resin inlays. 1. Adaptability to the experimental MOD cavity prepared in an acrylic block].

The adaptability of composite resin inlays was examined. CR Inlay and INLAY/ONLAY were used as materials. After the CR Inlay was polymerized in a U-form metal mold, the dimensional changes were measured before and after heating. Furthermore, the composite resin inlays made according to the manufacturer's instructions were cemented in an MOD type cavity and the film thickness of the cement was measured. The polymerization shrinkage of CR Inlay was 0.63% in the inside of the inlay and after heating it increased to 0.71%. The film thickness of the cement in the case of CR Inlay was more than 250 microns and that in the case of the INLAY/ONLAY was more than 750 microns in the MOD type cavity. Dentacolor XS (a box type photo generator) was better than Wite Lite (a handy type photo generator) for the polymerization of CR Inlay. Because of the poor adaptation of the inlays and the difficulty in removing a inlay from a stone model for CR Inlay, perhaps polymerization shrinkage of the inlay should be compensated in some way.

Cementation↗

PubMed1989

Bonding stability and shelf life of GLUMA.

The long-term bonding stability and shelf life of the two dentin-bonding systems--GLUMA combined with Clearfil New Bond and HEMA combined with Clearfil New Bond--were evaluated by measurement of the tensile bond strength and the wall-to-wall polymerization contraction in the cylindrical dentin cavity. The tensile bond strengths of the two bonding systems did not decrease significantly after the specimens were stored in water at room temperature for a maximum period of 24 weeks. Since the bonding efficiency of the two bonding systems was not affected by the storing of these solutions in a refrigerator for a maximum period of 24 weeks, the shelf life of these agents is considered to be longer than 24 weeks.

Acrylates↗

PubMed1989

Effects of self-etching primers on dentin.

The effects of self-etching dentin primers on the hardness of dentin was evaluated by determination of the Vickers Hardness of both untreated dentin and dentin treated with different primers. Several experimental primers were prepared by dilution of dicarbonates or their esterified salts with different ratios of HEMA to obtain ratios of 5% and 35% by weight. Methacryloxyethyl succinate (MES) and Methacryloxyethyl phthalate (MEP) experimental primers caused less softening of dentin than did maleic acid diluted with HEMA or a commercial dentin primer (Scotchprep, 3M). A high correlation was observed between the pH of a primer and the hardness of dentin treated with the primer. A correlation was also observed between the hardness of treated dentin and the wall-to-wall polymerization contraction of a light-curing microfilled resin (Silux, 3M).

Acid Etching, Dental↗

PubMed1989

Investigation of self-etching dentin primers.

In order to simplify the dentin bonding procedures by combining the dentin cleansing and dentin primer steps, we investigated the efficacy of the four acidic monomers--monomethacryloxyethyl succinate (MES), dimethacryloxyethyl phosphate (DMEP), tertiary butylacrylamide sulfonic acid (TBAS), and 4-methacryloxyethyl trimellitic anhydride (4-META), diluted in 35% hydroxyethyl methacrylate (HEMA) solution--by measuring the maximum contraction gap of the visible-light-curing composite (Silux 3M, St. Paul, MN, USA) in the cylindrical dentin cavity mediated by the bonding agent (Clearfil New Bond, Kuraray Co., Osaka, Japan). More than five of the ten specimens which were pre-treated with an aqueous mixture of 35% HEMA and four functional monomers at the concentrations of 0.1 M, 0.2 M, and 0.3 M showed a complete marginal adaptation, and this result was the same as in the control group in which the cavities were cleansed and pre-treated with 0.5 M EDTA and 35% HEMA, respectively. Moreover, the procedures were simpler. Therefore, these four monomers are considered to be effective as self-etching primers.

Acid Etching, Dental↗

PubMed1989

Clinical study of an experimental gallium containing alloy.

The possibility for the clinical application of an experimental restorative material, which is composed of an Ag-Sn-Cu-Pd spherical alloy and a Ga-In-Sn-Ag alloy, was examined by observing periodic changes during class I restoration. In all of the restorations tested, the surface texture and the marginal integrity had deteriorated after a period of one year. Therefore, it was concluded that this metallic plastic filling material couldn't overcome physical and chemical stresses in the mouth, as a result, some improvement is required before this material can be substituted for the high copper amalgam.

Dental Alloys↗

PubMed1989

Adaptation of composites to the dentin cavity wall.

The cavity adaptation of marketed composite resins was evaluated by measuring the contraction gap width in a cylindrical dentin cavity. Cavity walls were cleaned with neutralized 0.5 M EDTA and treated with an aqueous solution of 35% HEMA and a dentin bonding agent. The inorganic filler content was measured by weighing specimens before and after burning. When the composite which contained an inorganic component of less than 75 wt% was employed, a relatively low contraction value of less than 0.09% was obtained. On the other hand, for the composite with an inorganic component of more than 75 wt%, the gap values varied from 0.01 to 0.43%. However, using regression analysis, no statistically significant correlation was observed between the wall-to-wall polymerization contraction and the inorganic filler content.

Composite Resins↗

PubMed1989

Light activated resin containing organic dyestuff.

The physical properties of experimental visible light-activated resins containing dyestuff, which could be quickly discolored by irradiation was, evaluated by analyzing light absorbance characteristics and measuring micro Vickers hardness. The experimental resin, which was prepared by mixing equivalent weights of Bis GMA and triethyleneglycol-dimethacrylate, was colored by one of three organic dye stuffs, and camphorquinone and dimethyl-p-toluidine were added to activate polymerization. In the tested materials, the experimental resins containing Methylene blue and Nile blue A were discolored quickly after the start of irradiation, and this was considered to be useful for dental practice because an overfilled margin could be easily identified. The Vickers hardness number of the base resin decreased slightly by a level of 6% by adding the dyestuff.

Bisphenol A-Glycidyl Methacrylate↗