Presence of smear layer can reduce the efficiency of the root canal irrigants used for canal disinfection, simultaneously reduce the adhesion of the filling materials to the root canal wall, and increase the apical microleakage, leading to root canal treatment failure. Thus, the prerequisite for a clinically successful root canal treatment is the effective removal of smear layers.OBJECTIVE:
To assess the factors affecting the efficiency of chelating agents starting from its basic structure and action mechanism.METHODS:
The first author searched Medline (1999-01/2011-12) with the key words of “chelating agent, smear layer, root canal irrigation, root canal preparation” for the initial retrieval of relevant articles. After reviewing and quality assessment, a total of 50 articles were included.RESULTS AND CONCLUSION:
The factors affecting the efficiency of chelating agents for smear layer removal are as follows: the concentration of the fluid, volume used for irrigation, duration of irrigation, method of irrigation and other irrigating agents used in combination. Among these, time and the other irrigating agents used in combination are found to be the important factors affecting the efficiency with longer duration of irrigation responsible for the erosion of the dentin. Ultrasonic vibration is found to enhance the efficiency of chelating agent by allowing it to reach the apical third within the shortest duration. The combination of sodium hypochlorite and chelating agent is found to enhance the efficient smear layer removal although the best combination is yet to be determined.