The antimicrobial effects of subgingival chlorhexidine (CH) irrigations on the pathogenic flora in advanced periodontal lesions were assessed. Changes in the patterns of colonization within the subgingival sites were monitored by differential dark-field microscopy, in 16 patients, over a period of 10 weeks. In addition, changes in the clinical parameters of the diseased sites were also monitored. Initial base-line evaluations were made for both the clinical and microbiological parameters. 4 sites of moderate to advanced periodontal disease were selected in each patient. These were randomly irrigated with a single dose of either 0.2% CH gel, 0.2% CH solution, or physiological saline, while 1 site was left as a control. The patients were seen weekly, until the 5th week, then at the 7th and 10th weeks. At each appointment, a microbiological sample was taken from the subgingival region of each site, together with an assessment of the clinical indices. Results indicated that a single irrigation of an 0.2% solution of CH or 0.2% CH gel had a marked effect in decreasing the % of spirochaetes and, to some extent, motile bacteria. There was a concomitant shift in colonization to cocci, fusiform and filamentous organisms in pockets that were irrigated; this coincided with a reduction in the % of bleeding sites. Various patterns of colonization were observed which have been described and may assist in differential dark field (DDF) monitoring of lesions. Bleeding on blunt probing was found to be correlated with a flora dominated by spirochaetes. No other correlations were found over the 10-week period between the other parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

T6 antigen is a highly specific marker for human Langerhans cells (LC). Previous studies have demonstrated that Interleukin-1 (IL-1) and an IL-1 inhibitor (ILS) modulate LC T6 expression (T6E) in explant culture. The present study examined the in vitro modulation of T6E by two molecules: epidermal-cell-derived thymocyte-activating factor (ETAF), and a bone-derived protein (BP) implicated in the control of bone homeostasis. The effect of purified ILS was also examined. ETAF mimicked the stimulatory effect of IL-1 on LC T6E, while BP depressed T6E in a manner resembling that seen with ILS. No agents altered Class II (DR and DQ) expression by LC. BP was a specific IL-1 inhibitor, and did not inhibit thymocyte proliferation in the standard IL-1 bioassay in the absence of IL-1. These results demonstrate that molecules resembling IL-1 or ILS can modulate T6E, and implicate locally produced ETAF and ILS in the regulation of T6E in the oral mucosa in vivo.