Observation of fimbriae and flagella in dispersed subgingival dental plaque and fresh bacterial isolates from periodontal disease

The interbacterial matrix of subgingival plaque obtained from 12 individuals was examined by agar‐filtration negative stain electron microscopy. Flagellated bacteria were abundant in all samples from patients having periodontal disease. In addition, the plaques of all patients having periodontal disease, with the exception of two children diagnosed as having localized severe periodontitis, had varying amounts of long thin filamentous extracellular bacterial appendages morphologically identical to bacterial fimbriae. These appendages seemed to form into bundles to which bacterial membranes, blebs, and debris appeared to attach. Further studies examined the cell surface structures of bacteria freshly isolated from several of these plaque samples. Of 113 bacterial colonies examined, 49 (43.3%) had surface fimbriae like appendages. Actinobacillus actinomycetemcomitans, Bacteroides gracilis, Actinomyces odontolyticus, Capnocytophaga species, Fusobacteria species, and Haemophilus species had fimbriae. Only 4 of 113 colonies bore flagella. It was concluded that bacterial extracellular appendages resembling fimbriae are common morphologie components of plaque interbacterial matrix and may pay play a significant role in adhesive interactions within plaque. Although flagellated bacteria were commonly seen within subgingival plaques, few fresh isolates were observed to produce these structures.