Sonic vs Passive Ultrasonic Irrigation for Chronic Apical Periodontitis

Inclusion Criteria: 1. Agree to participate in this study and provide informed consent; 2. Age 18-59 years at the time of enrolment; 3. At least one permanent tooth diagnosed with chronic periapical periodontitis at root development stage of Nolla10th; 4. Able to follow up on schedule. Exclusion Criteria: 1. Allergies to any medications or materials necessary to complete the procedures; 2. Non-restorable teeth, teeth with severe defects, or teeth that need to be extracted due to orthodontic treatment; 3. Teeth with root canal treatment or vital pulp therapy; 4. Teeth with canal calcification or root canal instrument separation; 5. Teeth with root fracture or vertical root fracture; 6. Tooth with internal or external root resorption; 7. Patients with periodontitis; 8. Patients with orthodontic treatment; 9. Presence of dental phobia; 10. Women who are pregnant; 11. Patients who have taken medications that affect central nervous system, such as tricyclic antidepressant; 12. Patients who have taken medications that affect immune response, such as glucocorticoid or cyclosporin; 13. Patients after radiotherapy of tumor head and neck; 14. Patients who have taken medications that affect curative effect, such as bisphosphonates; 15. Patients with serious systemic diseases that can affect curative effect; 16. Participation in other clinical studies within the past several weeks; 17. Patients who are deemed unsuitable to participate in the study by investigators.