Abstract: The re-treatment of failed endodontic treatment includes complete removal of the root filling material, shaping root canals, disinfection with medicaments and ultimately filling. Removing as much filling material as possible is very essential for success. However, one of the greatest difficulties faced by re-treatment is achieving complete removal of filling materials. With the development of modern instruments and techniques, stainless steel hand files, engine-driven rotary files, solvents, heat-carrying and ultrasonic instruments are helpful devices aiming to remove completely the root filling material. This review was undertaken of the current literature on modern methods of filling material removal.

Key words: re-treatment, root filling material, nickel-titanium rotary file, dental operating microscope