Results: The SIRT1 rs3818292 AG genotype was associated with a 2-fold and 1.9-fold increase in the development of periodontitis 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). The gene discussed is SIRT1; the disease is periodontitis.