Abstract:Objective To investigate the level of Notch1 mRNA in peripheral blood mononuclear cells of patients with chronic periodontitis and its relationship with disease severity. Methods 150 patients with chronic periodontitis treated in the Department of Stomatology of Graduate School of Zhejiang University of Traditional Chinese Medicine and Lishui People’s Hospital from January 2017 to December 2018 were selected as the observation group, and 150 healthy people who underwent physical examination during the same period were selected as the control group. According to the severity of the disease, the observation group patients were divided into mild group (54 cases), moderate group (51 cases), and severe group (45 cases). Real-time fluorescence quantitative polymerase chain reaction was used to determine Notch1 mRNA levels in peripheral blood. Flow cytometry was used to determine T helper 17 (Th17) cells in peripheral blood. Double-antibody sandwich ELISA was used to measure interleukin-17 (IL-17) levels in peripheral blood. Results The levels of Notch1 mRNA, Th17 cells and IL-17 in the observation group were higher than those in the control group (P < 0.05). There were significant differences in the levels of Notch1 mRNA, Th17 cells and IL-17 in peripheral blood of patients with different severity of chronic periodontitis (P < 0.05), where those in the moderate group and severe group were higher than those in the mild group (P < 0.05) and those in the severe group were higher than those in the moderate group (P < 0.05). The levels of Notch1 mRNA, Th17 cells and IL-17 in peripheral blood of patients with chronic periodontitis after treatment were lower than those before treatment (P < 0.05). The levels of Notch1 mRNA in peripheral blood of patients with chronic periodontitis before treatment were positively correlated with the levels of Th17 cells (r = 0.548) and IL-17 (r = 0.572) (P < 0.05). Conclusions Notch1 may participate in the pathogenesis of chronic periodontitis by promoting the differentiation of Th17 cells. The level of Notch1 mRNA can reflect the severity of chronic periodontitis to a certain extent.