Modified Surface of PLGA Nanoparticles in Smart Hydrogel

Inclusion Criteria: * Root canal filled single rooted teeth with post treatment disease manifested by one or more of the following signs and symptoms: * History of recurrent acute and/or chronic periapical abscess * Pain on palpation and/or percussion at least after one month of previous procedure * Radiographic evidence of bone loss either as a new developing lesion or an increase in the size of a pre-existing one. Exclusion Criteria: * Teeth that were badly broken down indicated for extraction or with difficult isolation * Immuno-compromised patients. * Patients with history of taking antibiotics orally. * Periodontally affected teeth.