Postoperative Pain Associated With Three Endodontic Rotary Systems

Inclusion Criteria: * Systematically healthy patients, * maxillary or mandibular premolar teeth with acute irreversible pulpitis and indicated for conventional endodontic treatment. Exclusion Criteria: * Non-vital teeth, * teeth with apical periodontitis, * teeth requiring endodontic retreatment, * root resorption, * immature / open apex, * root canals with radiographic evidence of calcification, * presence of more than one symptomatic tooth in the same quadrant, * pregnancy, * medically compromised patients, * patients receiving medication for chronic pain, * patients who have taken analgesics in the last 12 hours before treatment. * teeth that have initial apical size more than 20, * teeth that could not be treated in a single session, * if any evidence of extrusion of root filling material noticed radiographically, patient will be excluded.