Inclusion Criteria:  Cooperative male children with age ranging from 10 to 13 years. All patients should have pulp necrosis with apical periodontitis in one or more upper incisor(s). Teeth included in the study were preliminarily evaluated by preoperative periapical radiographs and should have: single canal (type I vertucci's classification) with closed apices, periapical lesions of endodontic origin with a diameter ranging from 2 to 5 mm without any previous RCT procedure.  Exclusion Criteria:  immune-compromised patient or patient with complicating systemic disease. Patients received antibiotic therapy within the previous 3 months. Tooth having gross carious lesions, fractures or cracks involving the periodontium (un-restorable tooth). Tooth with root canal calcifications or resorption  6- Tooth with periodontal pockets of more than 4 mm depth, with or without endo-perio communication either concomitant or combined.