Inclusion Criteria:  Single rooted teeth with and without radiographic evidence of apical periodontitis and a diagnosis of pulp necrosis confirmed by negative response to cold test and clinically by absence of blood . 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.