Abstract: OBJECTIVE To investigate the pathogenic distribution and risk factors of root canal infection in patients with chronic periapical inflammation, and to explore the predictive value of microRNA (miR)-146a-5p, interleukin (IL)-1β, and IL-34 in root canal infection. METHODS A total of 94 patients with chronic periapical periodontitis admitted to Shaoxing Traditional Chinese Medicine Hospital from Jan 2018 to Dec 2022 and 101 healthy volunteers with orthodontic extraction during the same period were retrospectively recruited as the research subjects, which were divided into the study group and the control group. The root canal tissue fluid was collected for pathogenic examination and pathogenic distribution analysis of root canal infection in chronic periapical inflammation patients. The clinical data of the two groups were collected to analyze the high-risk factors for root canal infection in patients with chronic periapical inflammation using univariate and multivariate Logistic methods. Real-time fluorescence quantitative polymerase chain reaction (PCR) was used to detect the expression levels of miR-146a-5p, IL-1β and IL-34 in periodontal tissue of both groups, and the receiver operator characteristic (ROC) curve was drawn to analyze the predictive value of the three detection individual and combined in root canal infection in patients with chronic periapical inflammation. RESULTS A total of 113 strains of pathogenic bacteria were isolated from the root canal fluid of 94 patients with chronic periapical inflammation, including 63 strains of gram-positive bacteria (55.75%) and 50 strains of gram-negative bacteria (44.25%). Old age, sweet diet, short brushing time, dental caries, poor root canal filling, poor crown repair, and poor crown filling were the risk factors for root canal infection in patients with chronic periapical inflammation (P＜0.05). The expression levels of miR-146a-5p, IL-1β and IL-34 in damaged periodontal tissue of the study group were higher than those in the healthy periodontal tissue of the control group (P＜0.05). And the AUC of the combination of the three detection in root canal infection patients with chronic periapical inflammation was 0.935, which was higher than that of single detection (P＜0.05), with the sensitivity and specificity of 91.49% and 82.18%, respectively. CONCLUSION The risk factors for root canal infection in patients with chronic periapical periodontitis include root canal filling, crown repair and poor filling. The combined detection of miR-146a-5p, IL-1β and IL-34 in periodontal tissue had a high value in predicting root canal infection in patients with chronic apical periodontitis. Therefore, targeted antibacterial treatment or intervention measures could be given to high-risk patients according to the expression levels of miR-146a-5p, IL-1β and IL-34 in periodontal tissue, in order to reduce the incidence of root canal infection.