Restrepo-Restrepo FA, et al. - Researchers conducted this observational cohort study to retrospectively determine the strength and independence of the association of various patient-, tooth- and treatment-related prognostic variables with the outcome of root canal treatment in patients with pre-therapeutic apical periodontitis and to establish the concordance between those predictors evaluated by both cone-beam computed tomography (CBCT) and digital periapical radiography (DPR) after a 1- to 12-year follow-up period. The cohort of the research included 125 teeth in 84 people. Data reported that the success rate was 53.6%. The results from the present study indicate that several predictor variables related to the tooth and treatment, including tooth location, periapical radiolucency size, quality of the coronal restoration, magnification/illumination, disinfection of gutta-percha, time elapsed to definitive coronal restoration, as well as, the density of root canal filling can act strongly and independently to determine the outcome of the root canal treatment in teeth with pre-therapeutic apical periodontitis.