treatment of necrotic teeth using two engine-driven systems and patient’s postoperative pain: a double-blind clinical trial

introduction: one of the most important reasons for postoperative pain is the extrusion of debris from the apical foramen during preparation and shaping of root canals. the aim of this clinical trial was to evaluate the severity of postoperative pain with the use of two different engine-driven niti systems. methods and materials: ninety mandibular molars were randomly divided into two groups ( n =45), and root canal cleaning and shaping was done using either race or reciproc instruments. the severity of postoperative pain was determined with visual analogue scale (vas) at 4-, 12-, 24-, 48- and 72 h and 1-week intervals and postoperative pain was compared between the two groups. the chi-squared test and repeated-measures analysis were used to compare the data between the two groups. results: based on the results of the statistical analyses, the two groups were matched regarding the age and gender, with no significant differences. in addition, except for 4- and 24-h and 1-week intervals, postoperative pain was significantly less in the race group compared to the reciproc group ( p <0.001). conclusion: based on the results of the present study, use of race files for cleaning and shaping of root canals in necrotic mandibular molars resulted in less severe postoperative pain compared to reciproc files.