RESUMO
This study was conducted to evaluate the effect of apical terminus location of the root canal preparation on postoperative pain. Root canal preparation was completed in the first visit for sixty patients .The working length of the root canals were determined electronically by using apex locator and confirmed radiographically. The patients were divided randomly into three main groups according to apical termination of preparation [0.0, 0.5 and 1mm away from the apical foramen]. They recorded pain before treatment, 6, 12, 18, 24 and 48 hours after treatment. They assessed their severity of pain over the first two days following root canal preparation using a modified visual analog scale of [0-9]. Our results showed that Preparation to the apical foramen produced the highest significant level of postoperative pain at most of the time intervals. Otherwise no significant difference was found between the other groups