Further Studies on the Sensitivity of the Periodontal Syndrome in the Rice Rat to Dietary Antibiotics

¹ Harvard School of Dental Medicine, Boston, Massachusetts

1. Preliminary periods of 4-28-day administration of 0.05 per cent penicillin in the diet of rice rats before the usual 84-day assay period on periodontal syndrome-producing Diet 700 caused highly significant reductions in the prevalence of the periodontal syndrome.

2. Continuous administration in Diet 700 of 0.01 or 0.05 per cent oxytetracycline or chlortetracycline or of as little as 0.0025 per cent penicillin caused highly significant decreases in the periodontal syndrome.

3. Intermittent feeding of Diet 700 supplemented with either 0.01 or 0.05 per cent penicillin as infrequently as 1 day in 7 caused highly significant reductions in the periodontal syndrome.

4. The inclusion of 15 per cent cellulose in the periodontal syndrome-producing diet had no effect upon the number of areas with soft-tissue or calcified-tissue lesions but did cause a modest reduction in the extent of these lesions.