Background-The objectives were to measure the levels of gingival crevicular fluid (GCF) biomarkers and subgingival bacterial species in periodontally healthy and periodontitis subjects in order to explore relations among these biomarkers, the subgingival microbiota, and clinical parameters of periodontal disease.

Levels of IL-18 were higher in patients with chronic periodontitis compared with patients with gingivitis, even at sites with similar pocket depths. The presence of similar levels of red complex species in gingivitis sites from periodontitis patients and from gingivitis patients suggested that the higher levels of IL-18 were not associated with a different microbial challenge.

These results suggest that IFN-γ levels in GCF depend on the clinical stage of the site and not on the disease stage of the patient, but need to be expanded to a greater number of subjects and additional analysis of corresponding gingival tissue biopsies for cytokine gene expression.