The levels of interleukin (IL)-1β, IL-8, IL-10, IL-17A, and matrix metalloproteinase (MMP)-8 were evaluated in 59 patients with severe periodontitis, allocated to one of three treatment groups for scaling and root planing with adjunctive irrigants: Aquin (1% polyhexamethyleneguanidine phosphate (PHMG-P)) (n = 19), 0.2% chlorhexidine (CHX) (n = 21), or dH2O (n = 19). This evidence concerns the gene CXCL8 and periodontitis.