Periodontal disease in gnotobiotic rats.

The present investigation was carried out in order to assess the development of periodontal disease in germfree rats infected with microorganisms associated with human gingivitis, periodontitis and periodontosis lesions. One hundred and forty gnotobiotic rats of the Spraque-Dawley strain were weaned 21 days after birth and then randomly divided into five groups (four experimental groups and one control) consisting of 28 animals each. After weaning the animals of the experimental groups were infected with one of the following strains; strain I (Actinomyces naeslundii), strain 1073 (Eikenella corrodens), strain 381 (Bacteroides asaccharolyticus), strain 4 (Capnocytophage sputigena). Animals were sacrificed to provide specimens for examination 14, 28, 56 and 84 days after infection. Germ-free controls were sacrificed at the same time intervals. The degree of alveolar bone loss was assessed on defleshed and dried jaws. Microscopic assessments regarding loss of connective tissue attachment, degree of bone resorption, and degree of impaction of hair and bedding material were determined in histological sections. In addition, a morphometric analysis of the gingival tissues was carried out using a standardized morphometric test procedure. The results showed that germfree rats monoinfected with different bacteria associated with human periodontal diseases may suffer severe breakdown of the periodontal tissues. The degree of breakdown tended to increase with increasing experimental time. However, periodontal tissue destruction was obviously related to the impaction of hair and bedding material. In fact, only in areas with severe impaction of foreign material could gross destruction of the supporting apparatus be recognized.