Microbial changes associated with advancing periodontitis in STR/N mice

Subgingival bacteria in STR/N periodontitis‐susceptible mice and Swiss‐Webster nonperiodontitis‐susceptible mice were evaluated. STR/N or Swiss‐Webster mice with an age of 3, 8, or 13 months were sacrificed. Cultivable microorganisms and alveolar bone loss were correlated with the age of the mice. The proportion of Veillonella spp. were significantly higher in STR/N mice when compared with Swiss‐Webster mice at 3, 8, and 13 months of age. In addition, Haemophilus spp. were found to be significantly higher at 8 and 13 months and Streptococcus spp. at 13 months in STR/N mice. With increasing age, STR/N mice exhibited a progressive increase in bone loss and this correlated with a significant increase in the proportion of Streptococcus spp., Neisseria spp., Actinomyces spp., and Haemophilus species. On the other hand, Swiss‐Webster mice did not exhibit significant bone loss over 13 months and only Actinomyces spp. significantly increased between 3 and 13 months. The following microorganisms were not observed in any of the plaque samples; spirochetes, Lactobacillus spp., Eikenella corrodens, Actinobacillus actinomycetemcomitans, Actinomyces viscosus, Actinomyces naeslundii, Streptococcus sanguis, Streptococcus salivarius, Streptococcus mutans, dark‐pigmented Bacteroides spp., Fusobacterium spp., Capnocytophaga spp., and Branhamella species.