Microbial ecology of plaque in rats with naturally occurring gingivitis

Emiko Isogai, Hiroshi Isogai, Hiroko Sawada, Hisayuki Kaneko, Nobuyoshi Ito

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


The microbial ecology of adherent plaque was investigated in relation to the pathological findings of gingivitis in plaque-susceptible rats. Plaque developed in the gingiva of the lower incisor in plaque-susceptible rats, but not in plaque-resistant rats, after they were fed a commercial powder diet. With increase in plaque volume, the total counts of bacteria increased 109 to 1011/g. In the first 3 months, Bacteroides species increased and became the predominant population. Streptococcus species also increased at the same time. After 9 months, Fusobacterium species and oral Treponema species were recognized in increasing numbers. The anaerobic bacteria increased in proportion with the progression of plaque development. Bacteroides intermedius, Fusobacterium nucleatum, Streptococcus salivarius, and other species were isolated. Acute gingivitis was observed within 3 months, and subacute-chronic gingivitis was observed between 2 and 12 months. These findings suggest that proportional changes in the gingival plaque flora may uniquely contribute to the development of gingival inflammation in this experimental model.

Original languageEnglish
Pages (from-to)520-527
Number of pages8
JournalInfection and immunity
Issue number2
Publication statusPublished - 1985
Externally publishedYes

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases


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