Evaluation of Guided Endodontic Microsurgery and Two Different Retrograde Filling Materials

Inclusion Criteria: * Tooth is restorable pocket depth is less than 4mm and mobility in its normal limit ( less than 1mm) * Persisting or emerging disease following root-canal treatment when root canal re-treatment is inappropriate. * Tooth with acceptable endodontic treatment and have a new post and crown restoration, but have a persistent or enlarging periapical lesion ( size less than 10 mm) * Obstructed canal (the obstruction proved not to be removable, by passed and the risk of damage was too great). * Extruded material or instrument with clinical or radiological findings of apical periodontitis and/or symptoms are present. Exclusion Criteria: * Non restorable tooth * Contraindicating medical condition ( severe systemic condition and psychological condition) * Anatomical contra indication * Poor general oral status and supporting periodontal tissue.