Studies on analysis of biofilm formation in dental plaque and on control methods for the biofilm formation.

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Teeth with severe advanced adult periodontitis were extracted and investigated whether a bacterial biofilm concerned with bacterial colonization and growth of dental plaque by scanning microscopy. The results of the study revealed that bacterial biofilms are related to colonization and growth of supra and subgingival plaque. By scanning immunoelectron microscopic techniques using both secondary and back-scattered imaging with rabbit antibodies specific for each bacteria, Actinomyces viscosus, Streptococcus mutans and Eubacterium alactolyticum were detected near the glycocalyx structures in the supragingival plaque. In the plaque-free zone, Porphyromonas gingivalis and A.viscosus were covered with an amorphous film-like structure. P.gin givalis were found in 8/13 samples examined, and film-like structures coated several positive cells. A.viscosus were found in 6/11 samples examined, and tended to overlay the amorphous capsula and aggregated. These findings indicated that both P.gingival … More is and A.viscosus were possibly related to biofilm formation in the both supragingival and subgingival plaque. P.gingivalis possibly formed biofilm and resisted host response at the advancing front of subgingival plaque.We developed experimental in vitro model of biofilm formation by A.viscosus. The model used the modified Robbin's device, which provided continuous source of A.viscosus grown in a Brain-Heart Infusion broth (from 3 to 28 days). Formation of bacterial biofilm were observed by scanning electron microscopy during a 28-day experimental period. By day 3, attached A.viscosus were seen but glycocalyx-like structure was not observed. After day 7, A.viscosus grew and embedded in extracellular glycocalyx-like substances. We suggested that the- experimental model developed in the present study was useful for investigating the biofilm formation of plaque bacteria.Caries and periodontal disease are infectious disease caused by plaque bacteria, and it is difficult to throw light on the whole mechanism of biofilm formation in the dental plaque. However, based on the present results, we evaluated several methods of plaque control used, and presented the current concept for the rational plaque control. Less