Conclusions: Endodontic retreatment in 1 or 2 visits exhibited equally favorable periapical healing at 18 months, with no statistically significant differences between groups. Cestari Toia et al. J Endod 2022;48:4–14

This randomized clinical trial aimed to compare the effectiveness of endodontic retreatment of teeth with post-treatment apical periodontitis (PTAP) performed in 1 visit versus 2 visits on the reduction of cultivable bacteria and the periapical lesion volume (mm3) after 18 months of follow-up. M & M: 40 patients diagnosed with PTAP were selected and randomly divided into the following 2 groups: 1-visit retreatment and 2-visit retreatment with the placement of calcium hydroxide medication for 14 days. Cone-beam computed tomographic scans were performed at 2 stages: preoperatively and after 18 months of follow-up. Samples were collected before and after root canal procedures. Results: A higher bacterial load was found in the 2-visit group after the retreatment protocol, with no statistical differences between the groups regarding endotoxin levels and periapical lesion volume (mm3) at the 18-month follow-up analyzed by cone-beam computed tomographic imaging. Conclusions: Endodontic retreatment in 1 or 2 visits exhibited equally favorable periapical healing at 18 months, with no statistically significant differences between groups.