IL1B and periodontitis: Similarly, Meisel et al. [20] did not find correlations between IL-1 genotype and pocket bleeding in their epidemiological study, nor did Kornman et al. [5] and Liu et al. [1] in patients with untreated periodontitis, Jepsen et al. [26] in individuals neglecting hygiene procedures, or De Sanctis and Zucchelli [21] in patients under maintenance treatment after surgical regenerative treatment.