Child's Behavior Using Single Rotary File System Versus Manual Instrumentation in Pulpectomy of Primary Molars

Inclusion Criteria: * Patients: • Aged 4-6years, Medically free and Cooperative. * Teeth: * Restorable mandibular second primary molars with clinical signs or symptoms of irreversible pulpitis. Pre-operative Radiographic criteria: * Absence of internal or external root resorption. * Absence of periapical or inter-radicular radiolucencies. Exclusion Criteria: * Patients: * Uncooperative children. * Children with systemic disease. * Physical or mental disabilities. * Refusal of participation. * Unable to attend follow- up visits. * Refusal to sign the informed consent. Teeth: * Previously accessed teeth. * Mobile mandibular primary molars. * Pain on percussion. * Swelling in the vestibule or on palpation.