Effect of Vachellia Nilotica Versus Sodium Hypochlorite as Root Canal Irrigant on Postoperative Pain and Bacterial Load Reduction in Mandibular Premolar Teeth With Necrotic Pulp

Inclusion criteria: 1. Systemically healthy patient (ASA I, II). 2. Age between 20 and 40 years. 3. Male or female. 4. Patient who is able to sign and comprehend the pain scale (committed patient). 5. Mandibular single rooted premolars having the following criteria: * With single root canal. * Diagnosed clinically with pulp necrosis. * Absence of spontaneous pulpal pain. * Positive pain on percussion denoting apical periodontitis. * Slight widening of periodontal space or peri-apical radiolucency smaller than 3 mm (0-2mm). Exclusion criteria: 1. Medically compromised patients (ASA III or IV). 2. Teeth with: * Immature roots. * Vital pulp tissues. * Association with swelling. * Acute peri-apical abscess or acute exacerbation of a chronic abscess. * Mobility Grade II or III. * Previously accessed or endodontically treated. * Deep periodontal pockets more than 4 mm. * Vertical root fractures, coronal perforation, calcification, and external or internal root resorptions. 3. Patients who could not interpret the NRS. 4. Patients with diabetes, immune-compromising, and immunosuppression disease and pregnant women will be also excluded. 5. History of intolerance to NSAIDs.