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Biomedical subjects

E Masuhara

Publications and source records attributed to E Masuhara.

At least 73 records · Page 4Linked to original sources
PubMed1980

[Preparation of hard crown and bridge resin without PMMA powder (III) (author's transl)].

We have been studying hard crown and bridge resins. Mixtures of several polyfunctional monomers and a composite filler finely pulverized, prepared by polymerization of trimethylolpropane trimethacrylate in the presence of hydrophobic colloidal silica, were polymerized and their mechanical properties were studied. They were excellent and a sample from 2.6 E.UDMA comonomer was the best among them. The new filler possessed better affinity with matrices than composite fillers reported previously, presumably due to the reactivity with matrices. Introduction of this new filler into the hard crown and bridge resin preparation must improved the resins remarkably.

Crowns↗
PubMed1980

[Heat treatment of gold alloy to get adhesion with resin (author's transl)].

Combination of gold alloy and resin is common to prepare prostheses and restorations in dentistry. However, durable adhesion between gold alloy and resin has not been achieved, and mechanical retention which possesses many disadvantages is indispensable to fix them with each other. In our previous report, we had prepared a 4-META adhesive opaque resin and made sure of its excellent adhesiveness to dental non-precious alloy. Here, we developed a new method to change gold alloy surface adhesive and studied the adhesion between 4-META opaque resin and the modified alloy surface. The treatment is consisted of heat treatment and acid pickling. 4-META opaque resin could adhere strongly to treated gold alloys and the adhesive bond strength was 250 Kg/cm2. Moreover, durability of the adhesion is excellent and the value did not decreased even after subjected to 2000 cycle of thermal cycling (4 degrees C and 60 degrees C) or long immersion in water at 37 degrees C.

Adhesiveness↗
PubMed1979

[Preparation of hard crown and bridge resin without PMMA powder (author's transl)].

Elimination of PMMA powder to prepare better hard crown and bridge resin had been pointed out by the authors even though polyfunctional methacrylates were used. Application of hydrophobic coloidal silica instead of PMMA pearl with triethyleneglycol dimethacrylate and Bis-GMA was studied. Polyermization was carried out in the hot air stream at 120 degrees approximately 130 degrees C or in a pressure vessel at 4.5 kg/cm2 gauge, 100 degrees C. Mechanical properties, brinell hardness, compressive strength, an amount of water sorption, comparative average abrasion loss depth with those of PMMA, were measured. They were improved very much by this new system.

Acrylates↗
PubMed1979

[Properties of polyfluoroethylene-copolymers for the denture base lining material (author's transl)].

Silicone rubber is conventionally used as a lining soft material for denture base. However it still has some properties to be improved, such as poor adhesive strenth with acrylic resin, discoloration, degradation and growth of candida. We attempted to apply chemically-stable polyfluoroethylene-copolymers for this purpose. The terpolymers consisting of difluoroethylene, tetrafluoroethylene and chlorotrifluoroethylene (or hexafluoropropylene) were prepared and tested for tensile strenth, adhesive strength to acrylic resin, water sorption, contact angle, shore hardness, and toxicity by hemolysis test, cell culture test and extraction test. One of the selected terpolymer showed less water sorption (0.1 mg/cm2), stronger tensile strength (160 kg/cm2) and adhesive strength (110 kg/cm2) than the silicone rubber lining material. The toxicity test results suggested that the terpolymer will pose a low potential acute toxicity in vivo. All the test results seem to suggest that the polyfluoroethylene elastomer described here is a promising soft liner material for denture base.

Acrylic Resins↗
PubMed1979

[Analysis of eluate extracted from dental filling resin by high performance liquid chromatography (author's transl)].

Since the residual monomer of cured filling resin has been implicated in toxicological effects, a high performance liquid chromatography (HPLC) was used to analyze the eluate of bisphenol A diglycidylmethacrylate (Bis-GMA) and methyl methacrylate (MMA) type resins presently used. The main chemicals of the eluate from resin into three kinds of solution, water, 85% methanol water solution and 100% methanol were the residual monomers which formely were Bis-GMA, triethylenglycol dimethacrylate and latterly MMA. Residual initiators, benzoyl peroxide and hydroquinone were also determined. This investigation has shown that HPLC is rapid, reliable and an acurate method to analyze the residual monomers of cured dental filling resins.

Chromatography, High Pressure Liquid↗
PubMed1979

[The in vitro biological evaluation of dental cements using elution and binding by bovine serum albumin (author's transl)].

In order to evaluate in vitro biological properties of dental cements sixteen different cements including zinc oxide eugenol (ZOE), EBA, resin, polycarboxylate, glass ionomer cement and calcium hydroxide base material were tested regarding elution and binding by bovine serum albumin (BSA). The persistency of elution over long time after subsequent transfer to fresh water was calculated at 210 nm absorbance with ultra violet spectrometer. Also the eluates obtained were analyzed by high performance liquid chromatograpy. The continuous leaching of eugenol from ZOE cement was observed. Binding of eluates from cement to BSA was evaluated spectrophotometrically by utilizing the competition with 2-(4' hydroxyphenylazo) benzoic acid (HABA). EBA cement showed the highest binding ability by BSA because of the leaching o-ethoxybenzoic acid from this cement. The relevance of protein and pulp toxicity is discussed.

Animals↗
PubMed1979

[Preparation of hard crown and bridge resin without PMMA powder (II) (author's transl)].

It had been required to improve mechanical properties of hard crown and bridge resins. We had pointed out that mixing of PMMA powder with crosslinking agents for fablication of crown or bridges was not suitable to get better materials. Several trials were taken place to eliminate the PMMA powder. Hydrophobic colloidal silica was a good candidate to replace PMMA. But it is required to improve handling properties. A mixing of monomers, Bis-GMA and triethylene glycol dimethacrylate, and the silica was polymerized and pulverized and then the powder was applied for the fablication. The mechanical properties did not change as direct application of colloidal silica.

Acrylic Resins↗