“…In this regard, gingival crevicular fluid (GCF) is the most attractive bioanalyte, whose composition, in the presence of inflammation in the body, may contain specific cells, components of serum, connective tissue, epithelium, and microbial flora [ 18 , 20 , 21 , 22 ]. Therefore, the molecular content of GCF represents a promising source of biomarkers [ 21 , 22 , 23 , 24 , 25 ] that may prove to be a source of important information, for example, for the assessment of the expression of genes encoding superoxide dismutase 1 (SOD1), glutathione peroxidase 1 (GPX1), and thioredoxin 1 (TXN1) in the saliva and gingival tissue of patients with periodontitis [ 26 ] or to determine the concentrations of selected non-enzymatic antioxidants in the gingival fluid and saliva of patients diagnosed with periodontitis [ 26 ].…”