CTRI

Postoperative pain is an unwanted yet, unfortunately a common sensation after endodontic

treatment. The incidence of postoperative pain was reported to range from 3% to 58%6 . Even severe pain may occur within 24 to 48 hours after therapy5 .After the treatment was finished, 12% of patients experienced severe pain within this time interval according to a visual analog scale (VAS)5. Irritants to the periapical tissues that can evoke pain sensation include medications or irrigating solutions.Antimicrobial debridement is a key step in root canal therapy. Bacteria play a primary role in the development of pulp necrosis, periapical pathosis, and post treatment disease1 . Mechanical instrumentation alone is not enough to render canals free from microorganisms. Several studies have proven the effectiveness of sodium hypochlorite for bacterial reduction in addition to mechanical cleaning and shaping . Sodium hypochlorite works because of its ability to hydrolyze and oxidize cell proteins, its release of free chlorine, and its pH of 11 to 12 . Because of the strong cell toxicity, an associated risk with the use of sodium hypochlorite is the inadvertent injection into the periapical tissues through the apical constriction of the root canal, leading to severe, painful postoperative complications. Sodium hypochlorite accidents have been reported in the literature. Teeth with wide open foramina or with apical constrictions damaged by resorptive processes or by iatrogenic errors during instrumentation are at an elevated risk for the extrusion of sodium hypochlorite. Moreover, if excessive pressure is used during irrigation or the irrigation needle is bound within the root canal and prevents the safe coronal outflow of the solution, large quantities of sodium hypochlorite may be pushed out into the periapical tissues and subsequently lead to tissue necrosis and postoperative pain . This causes a dilemma because it is known that a high volume and frequency of irrigation as well as the ability to reach the apical intraradicular tissues are necessary for effective disinfection.To prevent periapical tissue damage and lessen postoperative pain, a safe irrigation delivery system is desirable. Commonly, hypodermic or endodontic needles are used for irrigation. Recently, a new irrigation system, the EndoVac system (Discus Dental, Culver City, CA), was introduced to endodontics. Conventional irrigation works with positive pressure to flush the disinfecting solution into the root canal and force the irrigant out again coronally by displacement with new volumes of solution.The EndoVac system works with negative pressure. Briefly, an irrigation tip is attached to a conventional medical syringe containing the solution. Through this tip, irrigant is released into the pulp chamber. Overflow is prevented by a suction tip that is directly attached to the delivery tip and connects to the high-speed suction of the dental unit. A second tube, connected to the high-speed suction, is used for the attachment of cannulas of varying diameter for different levels of irrigation within the root canal. A stainless steel microcannula of size #32 with 12 small, lateral holes is used for the apical 0 to 3 mm. The tip is inserted to the working length and provides a constant flow of new

irrigation solution to the apical third by sucking it apically from the fresh reservoir in the pulp chamber and disposing the used solution through the evacuation tube toward the high-speed suction of the dental unit