DESCRIPTION: Post-treatment endodontic disease might occur due to the persistence of bacteria in the root canal system as a consequence of insufficient cleaning, untreated canals, inadequate filling or coronal/apical leakage. Non-surgical root canal retreatment is the first choice to re-establish healthy periapical tissues. The procedure requires complete removal of the filling material from the canal system to allow effective cleaning, shaping and re-filling. ProTaper retreatment files are designed to be used in sequence to remove filling materials, such as gutta-percha, carrier-based obturators and paste fillers. The three, easily identified files are designed for the different needs of unfilling before canal reshaping.