In model 1, the ORs of periodontitis in the middle Tertile (T2, total serum IgE; ≥67.3 kU/L and <269 kU/L) of total IgE was 2.067 (95% CI 1.269–3.367) compared to T1 (total serum IgE <67.3 kU/L). The gene discussed is IGHE; the disease is periodontitis.