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Biomedical subjects

E Masuhara

Publications and source records attributed to E Masuhara.

At least 19 recordsLinked to original sources
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↗
PubMed1979

[Application of 4-META on adhesive opaque resin. (Part 1) Adhesive strength and the stability (author's transl)].

Mechanical devices, which has been conventionally used for retaining thermo-setting acrylic resin veneers possesses disadvantage of poor marginal sealing and requires rather complicated procedure applying on the metal casting. An application of adhesive resins to overcome these disadvantages was studied. Adhesive opaque resin consisted of MMA, epoxy acrylate, TiO2 and adhesive monomer 4-META was prepared and the adhesive bonding strength between the opaque resin and Ni-Cr alloy which is for crown and bridge works, was measured. As the results, the opaque resin applied on the metal casting with proper surface treatment showed an excellent adhesive bonding strength of 260 kg/cm2. This value did not decreased even after subjected to 300 time thermal cyclings (4 degrees C and 60 degrees C). After a three months immersion in water at 37 degrees C, adhesive bonding strength decreased slightly to 190 kg/cm2.

Acrylic Resins↗
PubMed1979

[Application of 4-META on adhesive opaque resin. (Part 2) Improvement of adhesive stability (author's transl)].

We had reported 4-META adhesive opaque resin for a metal casting etched with HC1. The bonding strength was as excellent as 260 kg/cm2 after 300 times thermal cycles between 4 degrees C and 60 degrees C but it decreased to 70 kg/cm2 when immersed in water at 37 degrees C for 30 weeks. It was required to improve the stability of bonding against water penetration into the adhesive junction before the clinical application. Preparation of the passive state on the metal casting adhesive stability between this film and the opaque resin were studied in this paper. When the metal casting was dipped in conc. HNO3 for fifteen minutes, adhesive strength was 260 kg/cm2 even after a 30 weeks immersion in water at 37 degrees C or the 10 weeks at 80 degrees C. It could be concluded that the adhesive opaque resin possesses enough adhesive strength and the stability for oral application.

Acrylates↗
PubMed1978

Development of adhesive pit and fissure sealants using a MMA resin initiated by a tri-n-butyl borane derivative.

A new adhesive fissure sealant, which consists of a solution of 3% 2-hydroxy-3-beta-naphthoxypropyl methacrylate in methyl methacrylate (MMA), poly-MMA powder and an oxidized tri-n-butyl borane, a polymerization initiator, was developed. Tensile bond strength between an acid-etched bovine enamel and a poly-MMA bar joined by this sealant was 60 kg/cm2, and the value did not decrease much after 30 days immersion in water at 37 degrees C. Penetration of fuchsin into the sealant-enamel interface during a percolation test was not observed. SEM observation showed no voids between the enamel and the cured sealant.

Adhesives↗
PubMed1978

Spherical powder for retaining thermosetting acrylic resin veneers.

1. Nine different sizes of spherical powder were prepared, and their effectiveness as retentive devices was evaluated against those available commercially. 2. Smaller-diameter spherical powder (No. 5) gave the best results of all retaining devices tested. 3. The physical properties of the resins play an important role in the retentive strength with No. 5 retention beads. The retentive strength was reduced when brittle resin was used. 4. The retentive strength of the resin veneer was greatly affected by the angle of stress at the incisal resin. The retentive strength increased as the angle between the longitudinal axis of the specimen and the direction of stress decreased.

Acrylic Resins↗
PubMed1978

Studies on hemolytic activity of bisphenol A diglycidyl methacrylate (BIS-GMA).

To clarify the high hemolytic activity of BIS-GMA, the molar concentration producing 50% hemolysis (H50) and the partition coefficient inoctanol-water were determined using BIS-GMA and various types of methacrylates. It is suggested that the strong hemolytic potency of BIS-GMA is due to the high hydrophobic nature of the compound.

Acrylates↗