extrusion of infected dentin into the periapical tissue has been suggested as a major source of pain after endodontic treatment. Although debris extrusion is an inevitable finding even when instrumentation is limited to the confines of the canal, different armamentarium seem to be associated with different amounts of debris extrusion. Studies on the effect of various rotary files on post-endodontic pain are very few and have yielded conflicting results with some favoring full-sequence and others leaning towards reciprocal rotary systems. This study aims at assessing the intensity of post-endodontic pain following two different rotary systems, Reciproc and race.

Methods: in this single-blind, parallel-grouped randomized clinical trial a total of 150 otherwise healthy patients aged between 20 to 50 years old with a pulpal status of irreversible pulpitis for one tooth in the upper or lower molar region were analyzed. A clinician performed the endodontic treatment in two groups, a group instrumented using race and a third group with instrumentation performed using Reciproc rotary systems.

Inclusion Criteria:

• Inclusion criteria: the otherwise healthy patients were aged between 20 to 50 years old with a pulpal status of irreversible pulpitis for one tooth in the upper or lower molar region.

Exclusion Criteria:

• Exclusion criteria: previous endodontic treatment; a history of drug intake including corticosteroids; opioids and NSAIDs in the previous 12 hours; pregnancy; complicated anatomy (curves greater than 25 degrees); calcifications; internal & external resorption; open apices; periodontal disease; swelling & abscess; presence of periapical lesions; sensitivity to percussion and lack of occlusal contact.