Currently, several studies have evaluated the levels of IL‐23 and IL‐17, including their receptors, in patients with periodontitis in different biological samples such as gingival tissue [21, 22, 23], serum [24, 25], plasma [26, 27, 28], saliva [29, 30] and gingival crevicular fluid [23, 25, 31, 32, 33]. This evidence concerns the gene IL17A and periodontitis.