Genes related to oxidative stress pathways, such as SOD and CAT, have been associated with periodontitis,12 while microRNA genes are involved in inflammatory diseases by silencing several mRNA targets related to cellular processes, including cellular homeostasis, proliferation, differentiation, development, growth, and apoptosis,11 particularly the miR-9 family targets transcripts of inflammatory cytokines.16 This evidence concerns the gene CAT and periodontitis.