Retreatment methods and files used in endodontics

The retreatment aims to remove completely the root filling, to enable effective cleaning, shaping and filling of the root canal system. Instruments that have been used and tried for gutta-percha (GP) removal are many in number, including endodontic hand files, engine driven rotary files, ultrasonic tips and files, and heat carrying instruments. Chemicals are sometimes used as solvents. GP removal using hand files either with using solvents or without is time-consuming, especially when the filling materials are well condensed. Nickel–titanium (NiTi) rotary instruments have been used successfully in root canal cleaning and shaping. In the recent years, the ProTaperNiTi rotary system has been upgraded to the ProTaper Universal system, which includes shaping, finishing and retreatment instruments. The three retreatment instruments (D1, D2 and D3) are designed for removing filling materials from root canals, from the coronal, middle and apical portions of canals. The shaping and finishing instruments and the retreatment series have a convex cross section; however, D1 has a working tip that facilitates its initial penetration into filling materials. Present laboratory studies are done to evaluate the efficacy of ProTaper Universal retreatment files in removing GP from root canals. Root canal retreatment aims to eliminate or to substantially reduce the microbial load from the root canal.