The effect of intensive antibacterial therapy on the sulcular environment in monkeys. Part I. Changes in the bacteriology of the gingival sulcus.

The changes induced in the bacteriology of the gingival sulcus were evaluated as part of a study considering the keratinizing potential of the sulcular epithelium when bacterial plaque was essentially eliminated. Two Rhesus monkeys were scaled and placed on a daily therapeutic regimen which included a prophylaxis, systemic tetracycline, and topical chlorhexidine. Over the 40 day experimental period and 74 days post-therapy, subgingival plaque samples were taken periodically. The plaque samples were cultured anaerobically and aerobically to determine the predominant bacterial flora. The total cultivable bacterial flora decreased from initial levels by greater than 99.9% with the antibacterial therapy. The flora shifted with therapy from one dominated by anaerobic organisms, including Bacteroides melaninogenicus (18%) and Fusobacterium species (13.9%), to a flora dominated by organisms growing aerobically. During treatment B. melaninogenicus and Fusobacterium species were not detected in any sample. After cessation of all therapy the anaerobes increased to dominance again, but B. melaninogenicus remained undetectable through 74 days post-therapy.