A study on host-parasite interactions in human periodontal pockets.

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We observed subgingival plaque in 18 severe adult-periodontitis affected teeth by scanning electron microscopy. In the apical one-third zone of periodontal pockets, several bacterial species aggregated with glycocalyx-like structures, which comprised net-like and mucoidal structure. In the so-called "plaque-free" zone, two types of bacterial adherence were observed : bacterial cell walls directly contacted with the root surface, and microorganisms adhered to the root surface mediated by the glycocalyx net-like materials.After Providing informed consent, 30 teeth with severe advanced adult periodontitis were extracted, and the plaque-free zones were investigated with specific antibodies against four periodontal diseaseassociated bacteria by a scanning immunoelectron microscopy method. Porphyromonas gingivalis was actually found in the plaque-free zones in four of the seven samples examined, and Treponema denticola was detected in five of nine samples. Prevotella intermedia occurred in o … More nly one of the seven samples examined, and Actinomyces viscosus was identified in four of the seven samples. More than half of the number of the spirochetes and rods detected by secondary electron imaging in the plaque-free zones did not react positively with the four specific antibodies examined by back-scattered electron imaging. This suggests that several unidentified microorganisms were present in the plaque-free zones in addition to the above four bacterial species.We also examined immunohitologically the cell densities and distribution of T and B cells in periodontitis, and analyzed their relationship in terms of periodontal tissue destruction. T cells appeared in the low density of infiltrates and increased gradually with the number of total infiltrates, whereas B cells did not appear in the small infiltrates but increased rapidly with the number of infiltrates. The number of fibroblastic cells showed negative correlation with that of the total infiltrates and B cells, but it did not correlate with the number of T cells. These findings suggest that the T cells infiltrated into the imflamed sites at the onset and increased gradually with the development of inflammation, and that B cells infiltrated behind the T cells and their number increased rapidly with inflammation. Less