Assessment of Postoperative Pain After Using Two Formulations of Calcium Hydroxide Intracanal Medication .

Inclusion Criteria: * .single-rooted teeth with pulpal necrosis and symptomatic apical periodontitis with visible radiographic disturbance of periapical lamina dura. The diagnosis of pulp necrosis was confirmed by negative response to cold test, electric pulp tester and clinically by absence of blood upon access cavity . * Clinical signs of apical periodontitis. * Teeth with sufficient coronal tooth structure for adequate rubber dam isolation were selected . * Patients who are over 18 years old . Exclusion Criteria: * Presence of open apices * Presence of non-restorable teeth * Presence of large carious lesions approaching the root. * Presence of calcification or resorption . * Patients who had received antibiotics during the last 3 months . * Teeth with periodontal probing depth \> 4 ml. * Teeth with previous root canal treatment . * Teeth with fluctuant facial swelling . * Pregnant females.