The analysis revealed that the SIRT1 rs3818292 AG genotype was associated with 2-fold and 1.9-fold increased odds of periodontitis development under the codominant and overdominant models (OR = 1.959; CI = 1.239–3.098; p = 0.004; and OR = 1.944; CI = 1.230–3.073; p = 0.004, respectively). This evidence concerns the gene SIRT1 and periodontitis.