In 2009 Pradeep et al. (11) also published a case-control study in which they found that the lowest levels of IL-18 were in the control group patients and the highest levels in patients with periodontitis, with intermediate concentrations of this interleukin in the gingivitis group, and that the levels of IL-17 were imperceptible in all study groups. Here, IL18 is linked to gingivitis.