Influence of Irrigant Delivery Systems on the Incidence of Postoperative Discomfort in Oval Canals

Despite their proven efficacy in improving canal cleanliness and disinfection, theseirrigation protocols are not without drawbacks. Mechanical and chemical interactions maylead to extrusion of irrigants or debris beyond the apical foramen, potentially causingirritation of the periapical tissues. As a result, patients may experience varyingdegrees of postoperative pain or discomfort following treatment, depending on theirrigation method and activation technique employed.Manual Agitation:Manual agitation is a simple and cost‐effective method used to enhance irrigantpenetration and exchange within the root canal system. It involves the use of instrumentssuch as gutta‐percha cones or endodontic brushes to manually move the irrigant inside thecanal. Although this technique can improve irrigant distribution, its effectiveness islimited by the operator's ability and the lack of continuous flow or activation energy,making it less efficient in complex canal anatomies.Conventional Needle Irrigation:Conventional needle irrigation remains the most widely practiced method of deliveringirrigants into the canal. Typically, side‐vented or open‐ended needles are used todispense the solution within 1‐2 mm of the working length. While this technique allowscontrolled delivery, its major limitation lies in the restricted penetration of irrigantinto irregularities and apical areas due to vapor lock and inadequate fluid replacement.Consequently, canal cleanliness and disinfection depend heavily on the needle design,placement depth, and flow rate.Sonic and Ultrasonic Activation:Sonic and ultrasonic activation techniques utilize energy transmitted through oscillatingtips or files to enhance the dynamic movement of irrigants within the canal. Sonicdevices operate at lower frequencies (1‐10 kHz), generating acoustic streaming thatimproves debris removal. Ultrasonic systems function at higher frequencies (25‐40 kHz),producing vigorous cavitation and acoustic streaming effects that significantly enhancethe cleaning and disinfecting potential of irrigants. However, excessive activation orimproper use may increase the risk of irrigant extrusion and subsequent postoperativediscomfort.Negative Pressure Irrigation:Negative pressure systems, such as the EndoVac or SafeClean, were developed to minimizethe risk of apical extrusion and improve irrigant exchange in the apical third.Thesesystems deliver irrigant from the coronal portion while simultaneously applying negativepressure to draw the solution down the canal and aspirate it at the apex. This designenables effective irrigation of the apical region while maintaining safety and preventingperiapical irritation.There is limited clinical evidence comparing the effect ofdifferent irrigation/activation protocols on postoperative pain in canines and premolars.