This randomized, controlled, double-blinded clinical trial aims to directly compare the efficacy of Sonically Activated Irrigation (SAI) versus Passive Ultrasonic Irrigation (PUI) in the root canal treatment of teeth with chronic apical periodontitis, analyze potential influencing factors, and thereby identify a highly effective and safe root canal irrigation protocol. The ultimate goal is to provide an evidence-based rationale for optimizing irrigation technique selection and overall treatment strategies for chronic apical periodontitis.