The Effect of Intensive Antibacterial Therapy on the Sulcular Environment in Monkeys: Part II: Inflammation, Mitotic Activity and Keratinization of the Sulcular Epithelium

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Abstract
The effect of an almost complete elimination of bacterial plaque upon the sulcular tissues was studied in Rhesus monkeys. They received thorough scaling and polishing and daily antibacterial therapy for 40 days. Biopsies including the gingival sulcus area were taken periodically during experimentation. They were also taken up to 74 days after therapy was discontinued. Biopsies were evaluated histologically for inflammation and keratinization. Half of each biopsy was exposed in vitro to tritiated thymidine to determine mitotic activity of the sulcular and junctional epithelium. The Inflammatory Index decreased from 28.3 in the junctional epithelium (Zone A) and 30.3 in the sulcular epithelium (Zone B) to approximately 3 to 4 in both zones after 40 days of therapy. The Radioactive Index decreased from 24.7 in Zone A and 29.7 in Zone B initially to approximately 2.0 in Zone A and to less than 1.0 in Zone B at Day 40. Both Radioactive Index and Inflammatory Index approached pretreatment levels 74 days after cessation of antibacterial procedures. The most striking feature histologically was a progressive keratinization, demonstrated by specific stains, of the sulcular epithelium. This change was coincident with the decreases in bacteria, inflammation, and mitotic activity. This study achieved an alteration in the sulcular environment by producing a decrease in the number of bacteria, inflammation, and mitotic activity. Keratinization of the gingival sulcus became evident as the sulcular environment changed. It seems reasonable to postulate that reduction in the subgingival bacterial flora reduces inflammation, reduces mitotic activity and allows full differentiation of the sulcular epithelium.