Effect of infection with Eikenella corrodens on the progression of ligature-induced periodontitis in rats.

The periodontopathic ability of Eikenella corrodens 1073-R (EcR) on ligature-induced periodontal defects in immunosuppressed and non-immunosuppressed rats was studied bacteriologically and histologically. Silk ligatures were placed around the maxillary second molars of rats, and the rats were divided into eight groups. Four groups received cyclophosphamide (CY), an immunosuppressive agent, the day after ligature placement. On days 3 and 4, the oral cavities of the rats in all four groups were inoculated with 8 x 10(8) cells of live EcR. Rats were sacrificed on d 1, 3, 5, 8, 11 and 18. Alveolar bone resorption of ligated rats was enhanced by the implantation of EcR, although the number of total cultivable bacterial cells from ligated sites was not changed by the implantation of EcR. CY suppressed the number of white blood cells, inflammatory cellular infiltrates in gingival tissue, and repair of periodontal tissue, and enhanced bone destruction. The implantation of EcR in the ligature- and CY-treated rats also enhanced osteoclastic bone resorption. Without ligatures, high doses of CY or EcR inoculum did not result in periodontal destruction. These results indicate that it is possible to establish EcR in conventional rat flora with a ligature and that EcR causes osteoclastic bone resorption in this model.