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Biomedical subjects

M Takeyama

Publications and source records attributed to M Takeyama.

At least 181 records · Page 10Linked to original sources
PubMed1982

[Studies on dental self-curing resins (19) - adhesion of 4-META/MMA-TBB resin to pretreated dentine (author's transl)].

A new 4-META/MMA-TBB adhesive resin has been studied and the effectiveness on adhesion to tooth substrates and dental alloys was reported previously. Here we are showing affection of cleaner or etchants on the adhesion between dentines and the 4-META/MMA-TBB resin. The adhesive strength becomes superior, 18 MPa, when dentines have been cleaned with a 10% citric acid-3% ferric chloride solution. On the other hand an etchant, phosphoric acid or citric acid alone, is not so effective as the mixed solution and the strength decreases to 6 MPa. Scanning electron microscopic study on pretreated dentine with several solutions is also carried out and it is found that debris on dentine should be removed but that in tubules is not necessary to be cleaned up to get good adhesion.

Acrylic Resins↗
PubMed1982

[Studies on dental self-curing resins (20) - adhesion mechanism of 4-META/MMA-TBB resin to dentine (author's transl)].

Scanning electron microscopic studies on dentine surface cleaned with a mixture of citric acid and ferric chloride, fractured surfaces parallel to the tubules of dentine and dentine with the cured adhesive and the partially demineralized fractured surfaces, tensile fractured surface of the joint on the dentine and cured adhesive resin tags impregnated in tubules were carried out to clarify the adhesion mechanism. Infiltration of monomers into dentine is more important to get good adhesion with dentine than the interlocking at dentinal tubules due to impregnated resin. Monomers with both hydrophobic and hydrophilic groups like 4-META promote the monomer infiltration. The infiltrated and cured adhesive layer in dentine is observed at the subsurface dentine zone. This zone has excellent resistance against acid demineralization.

Acrylic Resins↗
PubMed1982

[Studies on dental self-curing resins (22) - adhesion of 4-META/MMA-TBB resin to enamel (author's transl)].

Bovine enamels cleaned with citric acid and FeCl3 which had been brushed or ground were joined with PMMA rods with the 4-META/MMA-TBB cement. Their tensile adhesive strength was measured after post-treatments. Stable adhesive strength such as 6.2 MPa was obtained on an enamel which was brushed and washed with an aqueous solution of 10% citric acid-3% FeCl3 for 30 sec. even after a 60 times percolation test between 4 degrees C and 60 degrees C. It is adequate to clinics. The value increased to 16.1 MPa on ground enamel. These results suggest that phosphoric acid etching, essential nowadays, is not necessary for good adhesion to enamel. Monomers with both hydrophobic and hydrophilic groups like 4-META possess affinity with tooth substrates and promote the infiltration of cements into the enamel. The infiltrated monomers polymerized in situ and strong adhesion with the enamel took place. Comparison of the tag length formed in the enamel by cements, MMA-TBB, HNPM/MMA-TBB, Phenyl-P/MMA-TBB and 4-META/MMA-TBB supports this consideration.

Acrylic Resins↗
PubMed1981

4-META opaque resin--a new resin strongly adhesive to nickel-chromium alloy.

1) A new adhesive opaque resin containing a reactive monomer, 4-methacryloxy-ethyl trimellitate anhydride (4-META), was prepared, and its application to thermosetting acrylic resin veneer crowns was studied. 2) The 4-META opaque resin was applied to a variety of nickel-chromium dental alloy specimens which had undergone different treatment, and endurance tests were conducted to evaluate the durability of adhesion. 3) Stable adhesion against water penetration was achieved with metal surfaces first etched with HCl and then oxidized with HNO3. A bond strength of 250 kg/cm2 was maintained even after immersion in water at 37 degrees C for 30 wk or at 80 degrees C for ten wk. Furthermore, this value did not decrease even after the specimens were subjected to 500 thermal cycles. 4) The 4-META opaque resin studied can eliminate the necessity for retention devices on metal castings. 5) The smooth 4-META opaque resin should have no adverse effects on gingivae.

Acrylates↗
PubMed1981

[Physical properties of adhesive 4-META resin cement (author's transl)].

4-Methacryloxyethyl trimellitate anhydride (4-META) had been reported to be a suitable monomer which promotes adhesiveness of PMMA rods with tooth substrates and metals. Previously an adhesive opaque resin which could eliminate mechanical retention devices from metal surface of crown and bridge metal frame was suggested. A new denture base resin, which is adhesive to metal denture plate, was also reported based on 4-META in MMA. We are going to publish a new application of 4-META to an adhesive dental cement in this paper. The physical properties of the new cement were measured: film thickness, 15 mu, tensile strength, 228 kg/cm2, compressive strength 920 kg/cm2, transvers strength , 530 kg/cm2, water sorption, 1.97 mg/cm2. Tensile adhesive strength of the cement was higher than 100 kg/cm2 between PMMA rods and dentine, enamel, dental alloys, and the stability was acceptable.

Acrylates↗
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↗
PubMed1980

Studies on peptides. LXXXVII. Synthesis of an octacosapeptide amide corresponding to the entire amino acid sequence of chicken vasoactive intestinal polypeptide (VIP).

The octacosapeptide amide corresponding to the entire amino acid sequence of chicken VIP was synthesized in a conventional manner, using a new arginine derivative, NG-mesitylene-2-sulfonylarginine, Arg(Mts). Treatment of a fragment, Z(OMe)-Thr-Asp-Asn-Tyr-NHNH2 with methanesulfonic acid or HBr was found to give a product with a low recovery of Asp, after aminopeptidase digestion. Ring closure of the Asp-Asn unit seemed to be responsible for this phenomenon. Deprotection with HF or TFA exhibited definitely less such a tendency. In the final step of the synthesis, all protecting groups, including the Mts group, were removed by HF in the presence of m-cresol and the deprotected peptide was purified by ion-exchange chromatography on CM-cellulose followed by isoelectric focusing in Ampholine pH 9--1. Synthetic peptide exhibited the identical Rf value with that of natural chicken VIP and was active as the natural peptide.

Amides↗
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↗