Effect of Simvastatin Versus Calcium Hydroxide Intracanal Medications on Post-operative Pain and Interleukin 6 and 8

Inclusion Criteria: * Patients who are free from any physical or mental handicapping condition with no underlying systemic disease. * Lower single rooted premolars: * Presence of pain with percussion. * Widening in the periodontal membrane space or with small sized periapical radiolucency. * Diagnosed clinically with symptomatic apical periodontitis. * Patients' acceptance to participate in the trial. * Patients who can understand pain scale and can sign the informed consent Exclusion Criteria: * Medically compromised patients * Pregnant women * Patients who are allergic to non-steroidal anti-inflammatory drugs. * Patients with two or more adjacent teeth requiring root canal therapy * If analgesics or antibiotics have been administrated by the patient during the past two weeks preoperatively. * Patients reporting bruxism or clenching. * Teeth associated with acute periapical abscess, swelling or a fistulous tract. * Greater than grade I mobility or pocket depth greater than 5mm. * Non restorable teeth. * Immature teeth. * Teeth with previous endodontic treatment. * Radiographic evidence of external or internal root resorption vertical root fracture, perforation, calcification.