Sequence of Irrigation in Endodontics

Irrigation has an important role during endodontic treatment. We are proposing a sequence for the different irrigating agents in order to achieve the best chemical preparation possible. During the last several years endodontics has progressed to the point for treatment to be less traumatic for the patient and less stressful for the dentist. However, if the use of nickel titanium rotary instruments has allowed us to gain time during endodontic treatment, it can also tempt us to neglect one of the main objectives of endodontics, that being the "cleaning" on which Dr. Herbert Schilder has emphasized since he insisted on "cleaning and shaping". It may be more appropriate to say, "shaping for cleaning". The main goal of the root canal treatment is to completely eliminate the different components of the pulpal tissue, calcification and bacteria, the placement of a hermetic seal to prevent infection or re-infection and to promote healing of the surrounding tissues if needed. There are many techniques available to accomplish the root canal preparation. There are also many techniques for filling the root canal system (ie. vertical compaction of warm gutta-percha, System B, lateral condensation). We must ask ourselves the question, "Why do we irrigate and what irrigation protocol will provide the cleanest canal?" In this context, let us remember that the shaping is the result of endodontic instruments while the cleaning results from irrigation. Therefore, we have two types of preparation. The first one is chemical and the second one is mechanical. It is the chemical preparation that will be discussed in the scope of this article. Moreover, it has been proven that there is a close correlation between these two types of preparation. In fact, with greater tapered preparations, the quantity and the concentration of the irrigating solution will be greater and will therefore better eliminate the smear layer.6 The files can clean only parts of the root canal system. They create a reservoir that can hold the different irrigating solutions, which will access and clean portions of the root canal system that the instruments cannot reach. In endodontics the most commonly used irrigating solution is sodium hypochlorite (NaOCl). It has many desirable qualities and properties. It performs bactericidal cytotoxicity, dissolution of organic material, and minor lubrification.9 But sodium hypochlorite by itself is not sufficient for total cleaning of