GCF is a region-specific fluid consisting of blood, host factors, and a plaque system originating from the plexus of blood vessels under the epithelium.26,27 In this study, GCF was used to determine marker levels and, according to our findings, IL-1β, GM-CSF, and MIP-1α levels in the GCF have a good ability to indicate advanced stages of periodontitis. This evidence concerns the gene CSF2 and periodontitis.