EndoVac third as observed by histological sections[12,16,17]. Nielsen

EndoVac system has the advantage to eliminate the debris formed from instrumentation and also the necrotic pulp remnants by using a safe delivery o the irrigants to the full working length in the root canal without the risk of apical extrusion11,12. Several researches have reported the advantages in EndoVac system comparing the other irrigation techniques, such as risk free procedure from the extrusion of apex, improved cleaning quality13,14,15,16. The researches conducted by various authors in their report, showed the advantages of the EndoVac system which improved the cleansing of the apical one third as observed by histological sections12,16,17. Nielsen and Baumgartner17, using extracted teeth with vital pulps, showed improved cleaning efficacy of EndoVac system at 1 mm from the working length in comparison to conventional irrigation. The authors also showed that the volume of irrigant delivered by the EndoVac system was at least 3 times higher, compared to conventional needle irrigation. These results were confirmed in an in-vivo study where the EndoVac system showed a higher ability to clean the apical one third of vital pulp root canals.APICAL NEGATIVE PRESSURE IN PREVENTING EXTRUSION OF THE IRRIGANTSIrrigants are helpful in achieving the goal of cleanliness21,22. But certain irrigants could be extruded into the periapical tissues, which would lead to unwanted complications such as inflammation, hematoma and sometimes necrosis could also occur23,24,25. Hence, it is necessary to reduce the risks associated in root canal irrigation that would benefit the patient more26. In a study, Desai and Himel26, Brown et al.27, Myers and Montgomery28, and Roy and Laurence29, reported that the positive pressure irrigation could result in extrusion of apical root canal. But, Desai and Himel26, Fukumoto et al.30, and Mitchell31 demonstrated that negative pressure irrigation could be reducing the periapical extrusion. Desai and Himel researched the EndoActivator, Ultrasonic needle irrigation and RinsEndo. In EndoActivator, volume of extruded irrigants was very less comparing ultrasonic needle irrigation and RinsEndo. Hence, concerning extrusion negative pressure irrigation is comparatively safe. Apical negative pressure irrigation irrigated the root canal system effectively to the fullest of the working length32. This is due to the design of the micro cannulae, which avoids the vapour lock effect. However, the negative pressure irrigation could not completely activate the irrigants in the non-instrumented areas.IRRIGATION OF CURVED ROOT CANALS