Complete debridement and disinfection of the pulpal space are considered to be essential for predictable long- term success in endodontic treatment. Residual pulpal tissue, bacteria and dentin debris may persist in the irregularities of root canal systems, even after meticulous mechanical preparation. Irrigation is a critical component because irrigants can reach areas inaccessible to instruments. Therefore, several irrigating substances have been recommended for use in combination with canal preparation, including sodium hypochlorite (NaOCl), chlorhexidine gluconate, 17% EDTA, citric acid, MTAD and 37% phosphoric acid solution. However, if these substances remain in the root canal, they might affect the penetration of the resin sealer in dentin and its polymerization. They might also degenerate dentin if they have a negative effect on the collagen fibres. It has long been recognized that the antibacterial effects of chemo-mechanical procedures can be enhanced by the subsequent placement of an antimicrobial intracanal medication, particularly in those cases of exudation, haemorrhage, perforation, root resorption, trauma or incomplete root formation. Nevertheless, the efficacy of both procedures also depends on the vulnerability of the involved microbial species present in the root canal system. Moreover, in order to avoid re-infection of the cleansed space, not only the placement of a host-compatible root canal filling but also of a permanent coronal restoration must be performed.