The present study shows adherence of Treponema denticola L12D and Treponema vincentii RitzA to guinea pig ear epithelial cells in vitro. The number of adhering organisms was positively related with the treponemal concentration and contact time. Incubation of washed T. denticola L12D and T. vincentii RitzA organisms or their culture supernatants with the epithelial cells induced morphological damage and detachment of these cells. In addition, indications for inhibition of epithelial cell proliferation were found. The activity of the supernatants was dose dependent, heat sensitive, and sensitive to sulfhydryl-containing components, suggesting the presence of enzymatic activity that might be of importance in the pathogenicity of these oral treponemes.

Attachment of gingival tissues to the protruding post of an endosseous dental implant is of great importance for the prognosis of its clinical success. Little is known about the requirements an implant material must meet to secure a durable permucosal seal. The objective of this study, therefore, was to gain insight into the morphology of epithelial cell-implant interfaces for a number of well-known or potential implant materials.Guinea pig epithelial cells were cultured on gold, titanium, carbon, hydroxylapatite, carbonate apatite, and modified polystyrene substrates The metallic and carbon substrates were obtained by vapor-phase deposition of thin films on polystyrene carriers. This technique allowed for the preparation of ultra-thin sections for transmission electron microscopy containing substrate as well as the cells adhering to it. The cultures on apatite were decalcified prior to sectioning.The results revealed that as attachment structures, focal contacts, extracellular matrix contacts, and hemidesmosome-like contacts could be distinguished. Hemidesmosome-like contacts were only observed on apatite and polystyrene and not on the metallic or carbon surfaces.The results of this study suggest the existence of some, as yet unknown, property of the substrate that determines the nature and the structure of the contact site with epithelial cells.

The attachment of 10 different Treponema denticola strains to monolayers of 4 types of epithelial cells derived from rat palatal epithelium, guinea pig ear, human buccal epithelium and human corneal epithelium was screened microscopically. Most T. denticola strains were able to attach to all four types of epithelial cells. The T. denticola strains seemed to attach better to epithelial cells derived from primary cultured material. The T. denticola strains showed different degrees of attachment. Scanning electron microscopy studies revealed that the attachment of T. denticola was not only tip-associated but occurred also at random points in close contact with microvilli of the epithelial cells. Attached spirochetes were non-uniformly distributed over the monolayers, indicating the presence of receptive subpopulations of epithelial cells in the monolayers.

In the present study an assay for the attachment of T. denticola to epithelial cells is described. An indirect immunohistochemical staining method, using two native polyclonal antisera, revealed dark-brown coloured spirochetes attached to rat palatal epithelial cell (RPE) monolayers. In addition, two morphologically distinct populations of RPE cells could be distinguished in the monolayers when using phase contrast microscopy. One minor population consisted of isolated rounded RPE cells that were lying on top of a confluent monolayer of flattened RPE cells. The rounded RPE cells were more receptive for the attachment of T. denticola than the flattened cells. The rounded RPE cells were evenly distributed over the monolayer, but the attachment of spirochetes to the rounded cells was greater at the edge than in the centre of the monolayers. The percentage of rounded RPE cells with attached spirochetes depended on the incubation time (optimum 6 h), temperature (optimum 37 degrees C) and pH (optimum 7.0). It is speculated that the attachment of T. denticola is a physical/chemical process of yet unknown nature and that differences in the number of microvilli and/or the amount of available receptors, between the two morphologically distinct cell types, accounts for the differences in the numbers of attached spirochetes.

We studied the nature of attachment of Treponema denticola ATCC 33520 to a microscopically distinct population of rounded rat palatal epithelial cells. The motility of the freshly harvested spirochetes appeared not be a prerequisite for attachment. Treatment of T. denticola ATCC 3350 with proteinase-K, heat, glutaraldehyde, formaldehyde and periodate oxidation decreased the attachment to the rounded rat palatal epithelial cells, indicating the involvement of protein and carbohydrate moieties. Trypsin treatment had no effect on the attachment. The attachment of T. denticola ATCC 33520 was decreased after treatment with native non-immune rabbit serum, native polyclonal rabbit serum, D-mannose, N-acetyl-D-galactosamine and sialic acid. The results indicate that the attachment of T. denticola ATCC 33520 to rounded rat palatal epithelial cells is mediated by trypsin-resistant adhesin(s) of protein and carbohydrate nature, with affinity for D-mannose, N-acetyl-D-galactosamine and sialic acid.