IL4 and periodontitis: The aim of the present exploratory subanalysis was to evaluate the role of the IL-1A −889, IL-1B +3954, IL-4 −34, IL-4 −590, GATA-3 IVS4 +1468 and COX-2 −1195 gene loci in patients with periodontitis after a non-surgical periodontal therapy with or without additional adjunctive systemic antibiotics.