Postoperative pain after the removal of root canal filling material using different techniques in teeth with failed root canal therapy: a randomized clinical trial

Objectives: This study evaluated the intensity and duration of postoperative pain after the removal of root canal filling material in retreatment procedures of upper incisor teeth with chronic apical periodontitis, using different techniques. Materials and methods: One hundred and thirty-five patients requiring retreatment of upper incisor teeth with chronic apical periodontitis were included in the study. The patients were assigned to three groups of 45 patients, according to the method used to remove old canal filling material. In group 1, canal filling material was removed using hand files. In group 2, the canal filling material was removed with ProTaper universal retreatment (PTUR) instruments. In group 3, Reciproc instruments were used to remove canal filling material. Teeth were then medicated with calcium hydroxide and sealed using temporary filling material. The presence of postoperative pain was assessed after 6, 12, 24, 48 and 72 h, 7 days, and finally after 10 days. Results: In all time intervals, except for 72 h, 7 days and 10 days, group 1 participants reported more intense postoperative pain than those in groups 2 and 3 (p = 0.02). In all time intervals, there was no difference in the pain scores between groups 2 and 3 (p = 0.08). In all groups, the intensity of postoperative pain decreased over time. The required time to remove canal filling material was less for the Reciproc group compared to the hand and ProTaper retreatment groups (p = 0.032). Conclusions: Hand files caused greater postoperative pain after non-surgical endodontic retreatment (NSER) of upper incisor teeth with chronic apical periodontitis compared to the ProTaper retreatment and Reciproc files.