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Biomedical subjects

E Masuhara

Publications and source records attributed to E Masuhara.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1978

[Solubility and degree of hemolysis as methods for the in vitro evaluation of dental filling materials].

For the biological examination of dental resin filling materials, a solubility and hemolysis test is recommended as an in-vitro testing method. Solubility and degree of hemolysis were examined in various filling materials based on MMA and BIS-GMA. It was found that, at the beginning, solubility was considerably higher in MMA-containing materials than in the BIS-GMA systems, and that after a while the conditions were reversed. The degree of hemolysis decreased in the following order with the individual materials: 1. Posite, Sevriton, Adatpic, 2. Epoxylite, Smile, Palakav, 3. MMA-BPO/Amin and MMA-TBBO. Comparison between the MMA and BIS-GMA monomers showed that corresponding to the same molar amounts, BIS-GMA materials developed a higher degree of hemolysis.

Dental Materials↗
PubMed1978

[Polymerization shrinkage and fitness of denture (author's transl)].

Polymerization shrinkage causes dimensional change of denture during the processing. We can not control the amount of shrinkage but can control the initiation points and the direction of polymerization. Heat conductivities of dough and mould, the distance from heating or cooling place, and amount of MMA etc. have influence on the polymerization. Polymerization shrinkage mainly appears on the point where polymerize last. In the case of heat processing the shrinkage mainly appeared on the point where heat supply was slow. On the other hand in that of self-curing resin, the polymerization starts at the center of the mass when the mould is immersed in an ice water bath and the shrinkage appeared on the surface of mass. Dentures were prepared by heat processing resin conventionally heated in a water bath, heated from mucous side only on a heat plate, and self-curing fluid resin. An amount of filled light body silicone impression materials between the denture and cast was minimum in the case of the one side heat processed denture. That was middle in the self-cured. The maximum case was conventional heat cured denture.

Composite Resins↗
PubMed1978

[Preparation of clear thermosetting resin for veneered crown from several bisMEPP monomers (author's transl)].

The whitish translucent shade of a thermosetting resin cured from a mixture of a 2,2-Bis (p-methacryloxy (ethoxy)1-2 phenyl)-propane monomer and PMMA pearls makes it difficult to reconstruct a shade of the natural tooth. The attempt to improve the transparency of the mixed polymer was made in this study. Varying the molecular weight of BisMEPP monomer, PMMA polymer and curing temperature, cured specimens were prepared and their transparency was measured with a spectrophotometer. The results obtained are as follows. 1) In any molecular weight of PMMA, BisMEPP with 2.3 to 3.3 average number of ethylene oxide linkage showed the highest transpalency on the specimen. 2) With increasing the curing temperature, transpalency of the specimens made from BisME4.0 PP increased. With another molecular of BisMEPP, transpalency of the cured specimens showed the highest transpalency at the curing temperature of 120 degrees C. 3) With increasing the molecular weight of PMMA, the transpalency increased.

Acrylates↗
PubMed1978

[Studies on dental self-curing resins. (17). Adhesion of PMMA with bovine enamel or dental alloys (author's transl)].

We synthesized 4-methacryloxyethyl trimellite acid (4-MET) and anhydride (4-META), and tried them as a reactive comonomer for adhesives to bovine enamel. In the case of non-etched enamel, tensile adhesive strength was 40-50 Kg/cm2 after one day immersion in 37 degrees C water, but it decreased below 10 Kg/cm2 after a month immersion in 37 degrees C water. It could be concluded that this adhesion was not sufficient for practical usage. Then we applied this method to an etched enamel. After a series of experiments we concluded that it was necessary to etch bovine enamel surface with 30% citric acid for practical usage. Adhesion of some dental alloys with a PMMA rod was also studied and adhesive strength in Co-Cr alloy was over 150 Kg/cm2 either after one month immersion in 37 degrees C water or 60 times thermal cycles between 4 degrees C and 60 degrees C.

Adhesiveness↗
PubMed1978

[Effect of cross-linking agents on mechanical properties of a fluid resin (author's transl)].

Effect of several cross-linking agents added to MMA on the mechanical properties of self-cured fluid resins was studied. The cross-linking agents were 2,2-bis (4-methacryloxyethoxyphenyl) propane, trimethylolpropane trimethacrylate, neopentylglycol dimethacrylate, hexamethyleneglycol dimethacrylate and 1,2-polybutadiene. Their concentrations in MMA were 1,3,5 and 10 wt%. Measured mechanical properties were Brinell hardness, tensile strength, impact strength and transverse strength. The best composition was 5% neopentylglycol dimethacrylate in MMA among studied samples. Microscopic observation of the surface after tensile test suggested that diffusibility of cross-linking agents into PMMA powder affected the mechanical properties. Mechanical properties of both matrix and powder, and their adhesion at the interface had influence upon the mechanical properties of resins processed by powder-liquid method.

Acrylates↗
PubMed1978

Evaluation of polysulfone as a potential biomedical material.

In the course of preliminary screening of various potential biomaterials, polysulfone (PS) has been found to have good biocompatibility (1,2). This paper describes the detailed results of evaluation of PS by several methods. Although a number of screening programs for biomaterials have been published (3,4,5,6,), we used our own program in this experiment.

Animals↗