Efficacy of Two NiTi Rotary Retreatment Systmes in Removing Gutta-Percha Obturated with Two Root Canal Sealers from Curved Root Canals : (An in Vitro Study) /

Abstract

Endodontic failure can be attributable to inadequacies in shaping, cleaning and obturation, iatrogenic events, or re-infection of the root canal system when the coronal seal is lost after completion of root canal treatment. Leakage and bacterial contamination are the most causes for root canal treatment failure. The main goal of non-surgical endodontic retreatment is to restore the integrity of the peri-apical tissues following ineffective root canal treatment or re-infection. Non- surgical retreatment includes complete removal of the pre-existent endodontic filling material to allow elimination of necrotic tissues. Safe, successful and effective removal of root filling materials is an integral component of non-surgical root canal retreatment. Access to the root canal system must be achieved in order to negotiate to the canal terminus so that deficiencies in the original treatment can be removed. Different techniques have been proposed for the removal of filling materials from the root canal system, including the use of hand files, Gates Glidden burs, nickel-titanium (NiTi) rotary instruments, solvents, heat pluggers, ultrasonic instruments and lasers. Many factors affect the efficacy of the removal of gutta-percha among which: root canal curvature, the initial root canal cross section and any previous shaping and filling procedures. To improve efficacy and retreatment success several NiTi rotary systems have been developed as Protaper Universal retreatment files and M-two retreatment files which were designed to be used to remove filling material.