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Biomedical subjects

H Hisamitsu

Publications and source records attributed to H Hisamitsu.

At least 55 records · Page 3Linked to original sources
PubMed1992

Possibility of allergic reaction to dentin primer--application on the skin of guinea pigs.

We studied the allergic reaction of guinea pigs to glyceryl methacrylate (GM), hydroxyethyl methacrylate (HEMA) and meso-erythritol methacrylate (EM), which are used as dentin primers. On the 18th day of the application test, when macroscopic investigation revealed an inflammatory reaction, the methacrylic acid-treated group showed marked eschar formation in comparison with the control group. In each of the dentin primer groups, a slight degree of skin redness was noted, but there were no serious symptoms. On the 25th day, the applications were resumed macroscopic inspection on the 32nd day found eschar in the methacrylic acid group only. Therefore, this experiment with dentin primers suggests a delayed allergic reaction. Local irritability test showed a more severe reaction than the application test. In this test, all experimental dentin primers and methacrylic solution promptly showed inflammation, and the chemical compound, methacrylic acid was a factor in inflammation.

Animals↗
PubMed1992

Application of the environmental SEM in human dentin bleached with hydrogen peroxide in vitro.

The environmental SEM (E-SEM) can be used unfixed biological samples under a low vacuum and wet condition. In this study, the fractured dentin of unfixed human teeth was treated with a 30% hydrogen peroxide solution (H2O2) for the examination of tooth-bleaching prior to the E-SEM and a conventional SEM. The peritubular matrix (PM) always showed a few cracks along the long axis of a dentinal tubule, and the ends of fine fibrils rose to the smoothly changed surface of the intertubular matrix (IM). The E-SEM with non-fixation and the conventional SEM following fixation indicated that the hydrogen peroxide solution easily permeated the PM and dissolved the non-fibrillar substance including the cracks of the PM by the constriction. In the IM, the solution may partially dissolve the organic parts within mineralized fibrils as well as non-fibrillar substance between the fibrils, although these remnants might precipitate again there.

Adolescent↗
PubMed1990

Nociceptive projection from tooth pulp to the lateral hypothalamus in rats.

The response of the rat lateral hypothalamic (LHA) neurons to tooth pulp electrical stimulation and the sensory projection pathway from the incisor pulp to the LHA were studied by electrophysiology and histology. 1) LHA neurons that responded to contralateral lower incisor pulp stimulation were found in the lateral part of the LHA. These neurons also responded to intensive tail pinch, but not to innocuous stimuli nor to applied glucose. 2) Histological study after injection of WGA-HRP into the lateral part of the LHA revealed many retrogradely labeled neurons in the ventral part of the periventricular gray (PVG) in the mesencephalon. 3) The PVG neurons responded antidromically to LHA stimulation and to contralateral lower incisor pulp stimulation. 4) After injection of WGA-HRP into the ventral portion of the PVG, many labeled cells were found in the contralateral subnucleus caudalis in the spinal tract of the trigeminal nucleus (NTST) where termination of the pulpal afferent was previously reported. It is thus suggested that the PVG is the most likely site of transmission relay of nociceptive inputs from incisors to the LHA.

Afferent Pathways↗
PubMed1984

Class 2 composite restorations: prevention in vitro of contraction gaps.

The present in vitro study has shown that it is possible to prevent marginal contraction gaps at composite restorations in the proximal section of Class 2 cavities by use of a condensable composite and adequate condensers. An explanation of condensation to eliminate the wall-to-wall polymerization contraction is suggested, and a possible complete Class 2 composite technique is outlined. The subject studied is only one of several problems that must be analyzed before acceptance of composite resins as Class 2 restoratives can be made possible.

Acrylates↗
PubMed1983

Porosity in microfill restorative composites cured by visible light.

Previous studies indicate that porosity in dental microfill composite restoratives reduces the clinical qualities of this group of materials. Porosity may decrease the optical quality of restorations and is probably a strong factor in reducing wear resistance of Class 1 fillings. In view of possibly eliminating this disturbing factor it was the purpose of the present work to study the effect of variables in the clinical technique on porosity. Initially it was found that filling by spatula as well as paste-paste mixing of non-porous microfill materials caused high porosity, and that the visible light curing microfill brands studied were pore-free as delivered by manufacturers. Consequently only this type of material was studied in detail and only when applied by syringing technique. Poor adaptation of composite to tube inside and to cavity walls as well as too small diameter of the tube tip were found to be factors greatly adding to porosity. In cylindrical cavities, 3 mm in diameter and 2 mm deep, porosity could be consistently reduced to zero by wetting the inside of the tube as well as the cavity walls by a drop of visible light curing monomer and by use of tube with a tip opening of 1.0 mm. Similar positive results were obtained for simulated Class 1 fillings. No adverse effects of this technique were found.

Chemical Phenomena↗
PubMed1978

Measurements of cervical undercuts of human tooth crowns.

The dimensional factors of the cervical undercut of the human teeth were measured. The facial and lingual undercuts showed considerable deviations in depth, width, and inclination to the crown axis and the food stream. The proximal undercuts showed a uniform depth of 1 +/- 0.3 mm with some deviations in width and inclination.

Bicuspid↗