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Biomedical subjects

T Fusayama

Publications and source records attributed to T Fusayama.

At least 73 records · Page 4Linked to original sources
PubMed1978

Physiological recalcification of carious dentin.

In order to confirm the ability of physiological recalcification of the human carious dentin, the first layer of carious dentin was removed from the symmetric cavities of bilateral pairs of human teeth, disclosing it by 0.5% basic fuchsin-propylene glycol solution staining. One of the pair teeth was immediately extracted and the other was left in the mouth after filling the cavity with polycarboxylate cement. The Ca content and hardness of the remaining second layer immediately and three months after the operation were compared by an electron probe microanalyzer and microhardness tester. They increased markedly after three months returning to the normal level from inside, proving physiological recalcification. A similar experiment was performed by using bilateral pairs of dog teeth with cavities having artificially decalcified dentin floor. After removing the fuchsin-stainable first layer, one of the pair was immediately extracted and the other was left in the mouth for three months after exposing or filling the cavity with various cements. As the Ca content was compared, a marked recalcification of the second layer of softened dentin was observed after three months returning to the normal level from the inside. The effect of different cavity treatment was slight.

Animals↗
PubMed1977

Effect of a carious dentin softener on the dentin and pulp.

The application of GK-101 to carious dentin softens the first or outer layer which contains denatured collagen. The second or inner layer of carious dentin, containing normal collagen fibers, is unaffected. The pulps of dog teeth were not affected by applying the solution to freshly prepared sound dentin.

Animals↗
PubMed1977

Structure and effects of non-gamma-2 amalgam.

The metallurgical structure of a non-gamma-2 amalgam was investigated by using metallurgical microscopy, surface, point, and line analyses by an electron probe microanalyzer, and a microhardness test. Referring to these findings, their effects on clinical results were then discussed. Findings were as follows: The residual dispersant particle was less hard than the gamma 1 matrix, but the ring around it was much harder than the gamma 1 matrix or the residual gamma particle. The improved mechanical properties seem to be the result of the presence of this ring. The gamma 2 phase was absent in this amalgam. The absence of gamma 2 phase seems to improve chemical resistance, to prevent the deformation by mercuroscopic expansion of amalgam margins, and thus to decrease their fracture potential. The minute gamma 1 crystals found adjacent to the ring around the residual dispersant particle seem to indicate that they were late in crystallization, resulting in low early strength.

Chemical Phenomena↗
PubMed1977

Collagen biochemistry of the two layers of carious dentin.

The amino acid composition and intermolecular cross links of collagen fibers in the two layers of carious dentin, differentiated by a 0.5% basic fuchsin-propylene glycol-stain, were biochemically investigated. No difference in the pattern of amino acid composition of collagen fibers was found between the first and second layers of carious dentin and the sound dentin. However, obvious differences in the intermolecular cross links of collagen fibers were found between the three layers. Namely, compared with the sound dentin, the second layer of carious dentin had decreased cross links and increased precursors. This change is considered to be reversible. Contrastingly, in the first layer, both the cross links and the precursors remarkably decreased. In addition, the hexitollysines (protein-saccharide compounds probably related to bacterial metabolism) were found and several peaks of unknown materials appeared. This indicates irreversible destruction of cross-linkage in the first layer of carious dentin.

Amino Acids↗
PubMed1977

Structure and hardness of four types of amalgam.

Three non-gamma2 and one conventional amalgams were compared for their structure and hardness. The Ag-Cu dispersants hardened the amalgam by generating hard Cu-Sn halos and diminishing the gamma2 phase. The Ag-Sn-Cu-In single composition alloy produced the hardest amalgam by its high hardness and the Cu-Sn reaction phase scattered as minute granules.

Chemical Phenomena↗
PubMed1976

Adhesion of polycarboxylate cements to dental casting alloys.

The adhesive strengths of four commercial polycarboxylate cements to five dental casting alloys were compared with the strength of a conventional zinc phosphate cement. The following results were obtained. (1) The polycarboxylate cements showed adhesion that was four to 12 times greater than that of the zinc phosphate cement to all alloys tested. (2) The adhesive strength of the polycarboxylate cements was greater to the chemically active substitute alloys, such as the copper, nickel-chromium, and silver-tin-zinc alloys. The adhesion of the polycarboxylate cements to the chemically stable gold and silver-palladium alloys was not as great, but was four to six times that of the zinc phosphate cement. (3) The difference in adhesive strength between the brands of polycarboxylate cement was generally slight or statistically insignificant.

Acrylates↗