口腔細菌を用いた in vitro の実験系における象牙質齲蝕の誘発
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概要
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The induction ability of dentinal caries by Streptococcus salivarius, Actinomyces viscosus, Streptococcus mutans and Lactobacillus casei were studied in vitro. The dentin blocks, extracted human caries-free premolars prepared with class I cavity (depth : 2mm), were incubated anaerobically with these four bacterial strains respectively. In addition to the monoinfective groups, mixed culture of L. casei with S. mutans or A. viscosus was also performed. One half of the culture broth was replaced by fresh medium and the pH of the culture medium was measured every 3 days through the experimental interval. After 4 weeks or 12 weeks, these dentin blocks were investigated with SEM, CMR, as well as with Brown-Brenn stain and enzyme immunohistochemical staining for light microscopical observation. The final pH of the S. salivarius group showed the highest value of 5.1, was higher than those of others, around 4.3. In every experimental specimen inoculated with bacteria, decalcification of dentin was observed in various degrees under the surface of the cavity. The bacterial invasion into dentinal tubules was observed in all of the experimental groups except S. salivarius group. When monoinfected, the bacterial invasion ratio was highest in the S. mutans group, followed by the A. viscosus group and the L. casei group. In the two mixed infection groups, high invasion ratio was also observed. However, it was revealed by the enzyme immunohistochemical staining that the invasion of S. mutans and A. viscosus were not observed but that of L. casei only. Meanwhile, the invasion ratio of L. casei was higher in mixed infection group with either S. mutans or A. viscosus, than that of monoinfection. These results suggest that lactobacillus may play an important role in the development of dentinal caries. Furthermore, the presence of other bacteria may promote the induction ability of dentinal caries of this bacterium.
- 九州歯科学会の論文
- 1988-12-25