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Biomedical subjects

N Shigeto

Publications and source records attributed to N Shigeto.

At least 37 records · Page 2Linked to original sources
PubMed1989

Corrosion properties of soldered joints. Part I: Electrochemical action of dental solder and dental nickel-chromium alloy.

The corrosion properties of contact between six Ni-Cr alloys and two dental solders were evaluated. Ni-Cr alloys with low Cr content coupled with silver solder induced continuous galvanic current, whereas Ni-Cr alloys with high Cr and some Mo content coupled with silver or gold solder induced galvanic current for a short time. Six Ni-Cr alloys were divided into two groups according to the dissolution of Ni, one with low resistance and the other with high resistance. The initial equilibrium was induced between high resistance Ni-Cr alloys and both solders by less current density, which implies a smaller degree of corrosive current than that in low-resistance alloys. Corrosion was observed in the silver solder coupled with high-resistance Ni-Cr alloy, but was not found in the gold solder coupled with both alloys. In soldering Ni-Cr alloy, it is better to use a gold solder and a high-resistance Ni-Cr alloy for corrosion resistance.

Chromium↗
PubMed1989

Evaluation of the methods for dislodging the impression tray affecting the dimensional accuracy of the abutments in a complete dental arch cast.

The dimensional accuracy of dies was evaluated in complete dental arch casts made by three different methods of dislodging the impression tray. By one method, the impression tray was dislodged parallel to the long axis of the abutment and by the other two the trays were inclined with the fulcrum at either the posterior or anterior region of the complete dental arch. The dimensional changes of the molar-die were significantly affected by the dislodging method in the inclined way but not those of the incisor-die. The anteriorly inclined method showed fewer dimensional changes than the posteriorly inclined method. On the other hand, the dimensional changes of the incisor-die were not significant by any dislodging method, but were observed when some impression material was used. If the impression tray is removed by the inclined way, the fulcrum should be chosen at a region remote from the abutment instead of at the proximal region.

Calcium Sulfate↗
PubMed1989

Metal hypersensitivity in dentists: a patch test study.

Patch test of dental alloys was conducted on dentists in the Department of Prosthetic Dentistry, Hiroshima University School of Dentistry. The positive rate of the first patch test in the test group was 47.1%, and that in the control group was 10.0%, showing a large difference between the two groups. Furthermore, a second patch test was conducted on those who showed a positive response together with pustular or follicular reaction. As neither positive response nor pustular or follicular reaction was observed in the second patch test, the results were regarded as negative. Only a very slight difference in the positive rate could be observed when the results of the two tests were combined. The results of the present study suggest that the possibility is small for dentists to develop metal hypersensitivity in normal clinical practice.

Adult↗
PubMed1986

Na/H exchange in cultured chick heart cells: secondary stimulation of electrogenic transport during recovery from intracellular acidosis.

Intracellular acidosis is capable of stimulating a rapid amiloride-sensitive Na/H exchange mechanism in the cell membrane of cultured chick heart cells. The sequence of changes of intracellular sodium and potassium contents during recovery from an acid load in heart cells was determined by atomic absorption spectrophotometry and correlated with electrophysiological measurements. Induction of an intracellular acid load by removal of NH4Cl from the bathing solution caused a rapid rise in sodium content that was amiloride-sensitive. Following a peak, sodium content declined concomitant with a rise in potassium content; these changes were ouabain-sensitive and corresponded with a ouabain-sensitive membrane hyperpolarization beyond the calculated potassium equilibrium potential. These observations indicate that pHi regulation in cardiac muscle, following an intracellular acid load involves extrusion of H+ by electroneutral Na/H exchange with the consequent rise in Nai stimulating the electrogenic Na/K pump to return Nai to control level. In the presence of amiloride (10(-4) M), the hyperpolarization was slower although still present: this suggests the existence of another sodium uptake mechanism which contributes to stimulation of electrogenic transport.

Action Potentials↗
PubMed1985

A decade of progress for the adhesive fixed partial denture.

The history of the development of adhesive fixed partial dentures was reviewed and present clinical problems discussed. Longitudinal studies are not available because adhesive prostheses with 4-META adhesive resin were introduced only a few years ago. However, scientific advances will make placement of resin-bonded metal prostheses a more stable, standard technique in fixed prosthodontics.

Adhesives↗