The study compares the prognosis of cases treated with "selective root retreatment" to the cases treated with traditional retreatment approach

Post-treatment apical periodontitis is an inflammatory disorder of peri-radicular tissues caused by either persistent or secondary intra-radicular infection .Conventionally, nonsurgical retreatment has been believed to be an ''all or none'' treatment approach in which the endodontist has to remove all restorations from the tooth and to remove the obturation materials from all the canals in order to perform thorough disinfection of the entire root canal system. Nowadays, All operations in the medical field are aimed basically at the conservation of the human body. The alternative concept allows the endodontist to formulate clinical treatment decisions with respect to the presence of periapical pathosis related to individual roots rather than the tooth as a whole.

The literature is lacking the clinical outcome studies dealing with the prognosis of cases treated with "selective root retreatment" concept so the aim of this study was to compare the prognosis of such cases in comparison to the traditional retreatment approach.

Inclusion Criteria:

• endodontically treated teeth
• multirooted teeth
• radiographic evidence of periradicular infection related to one root

Exclusion Criteria:

• medically compromised patients
• fused roots
• root resorption
• root fracture