Majority of the studies examining the GCF biomarkers were designed according to 1999 classification, to the best of our knowledge, this is the first study to evaluate clinical measurements, GCF IL-10/12/18 levels, IL-18/IL-10 ratio and their correlations within the same population in healthy controls and subjects with periodontitis using the 2017 classification system. This evidence concerns the gene IL18 and periodontitis.