Postoperative Pain and Substance P Levels After Bioceramic vs Calcium Hydroxide Intracanal Medicaments in Symptomatic Apical Periodontitis

Inclusion Criteria: * \- Patients aged 18-45 years with no sex predilection * Medically free Patients with no systemic conditions that can affect post operative pain response. * Patients should not be taking any pain medications 24 hours before intervention * Positive patients' acceptance for participating in the study * Patient able to sign informed consent * Permanent mandibular molars diagnosis with Symptomatic Apical Periodontitis * Permanent molars without any anatomical variations or severe curvatures Exclusion Criteria: * \- Medically compromised patients * Patients who have received antibiotic therapy within the last 2 weeks. * Pregnant or lactating women. * Patients with known allergy to any of the irrigants used. * Patients with swelling or acute peri-apical abscess or fistulous tract. * Teeth that have: * Wide or open apex . * Vital pulp tissue . * Periodontally affected with grade 2or 3 mobility. * Non restorable teeth . * Abnormal anatomy and calcified canals . * Pervious root canal treatment. * severe curved canal * Buccolingual and mesiodistal radiographs were taken to evaluate the root canal anatomy