One of the most important findings is the proof that the -590C/T polymorphism in the promoter region and VNTR in intron 3 of the gene encoding IL-4 affect not only the production of this interleukin, as described earlier [28–30], but also the production of other cytokines in response to the action of dental plaque bacteria or selected mitogens, this effect being much more conspicuous in patients with chronic periodontitis when compared with healthy controls. Here, IL4 is linked to chronic periodontitis.