Abstract
The method of facilitating accumulation of dental plaque by preparating the cavities on the mesiolinguales at the cervical portions of the upper molars of rat was devised.
Following the intramuscular injection with 1ml bismuth/kg/day for experimental period, the changes with lapse of the time after bismuth injection in gingival tissue were studied macroscopically, histopathologieally, and by means of electron probe microanalysis (EPMA).
In the conttrol group, preparatting no cavities on the teeth, injected with bismuth.
1. In the control group, no bismuth deposition was observed in the gingival tissue macroscopically and histopathologically.
2. Bismuth line formation in the gingival tissue.
1) Light microscopic observation.
a: After one day, no bismuth deposition was seen in the gingiva.
b: After 3 days, bismuth granules were deposited around the capillaries in the lamina propria of gingiva beneath the bottom of the sulcus epithelium.
c: After 7 days, a large amount of bismuth depositions was seen along the sulcus epithelium.
d: After 14-35 days, a large amount of bismuth depositions was seen over the whole lamina propria of the gingiva.
2) Electron microscopic observation.
a: After one day, fine bismuth granules were found around the capillaries in the lamina propria of gingiva beneath the bottom of the sulcus epithelium and basement membrane of the epithelium.
b.: After 3 days, these fine bismuth granules were observed in the lysosome-like vesicles of the fibroblast and histiocyte-like cells.
c: After 7 days, these fine granules gradually grew in size to form larger precipitation in the lysosome-like vesicle, and f ibroblast and histiocyte-like cells which had taken up a large amount of fine bismuth granules exhibited some degenerations which were at first apparent in the membrane system such as rough-surfaced endoplasmic reticulum and Golgi apparatus.
d: After 14-35 days, some degrees of degenerations were found in the cells in the lamina propria of gingiva and bismuth depositions were composed of degenerated nuclei, intracellular organelles of the cells and many aggregation of bismuth granules.
e: Throughout the entire experimental period, no fine bismuth granules were found within the epithelial cells of the gingiva and intercellular space.
3. The dark brown depositions within gingival tissue were indicated to be the sulfide bismuth by means of electron probe microanalysis.
