Objective: To compare in vitro irrigation systems’ efficacy in removing calcium hydroxide paste (Ca(OH)2) in single-root teeth. Methods: Sixty permanent teeth were prepared using ProTaper® rotatory instruments, up to F3. Specimens were split longitudinally into two halves, and two grooves located in the apical and coronal zones were created. Ca(OH)2 application into the grooves was assessed by radiographic and photographic methods. After the halves were reassembled in a silicone mold, teeth were randomly divided into experimental groups (n=15), testing Ca(OH)2 removal: 1 – CanalBrush™; 2 – E1 – Irrisonic tip; 3 – manual dynamic irrigation (MDI); 4 – XP-endo Finisher® (XP). A total volume of 10 mL of 2.5% sodium hypochlorite was used in each tooth. Finally, all groups were scored regarding the Ca(OH)2 remnants using the same methods as before. Statistical analysis was conducted using the Kruskal-Wallis test followed by Mann-Whitney U tests (with Bonferroni correction). A value of p<0.05 was considered statistically significant. Results: None of the techniques demonstrated 100% efficacy in both regions. CanalBrush™ was more effective in the apical region. Overall, E1 – Irrisonic tip and CanalBrush™ removed significantly more Ca(OH)2 than MDI and XP-endo Finisher® (p<0.05). Conclusion: Globally, E1 – Irrisonic tip and CanalBrush™ were more effective, although without statistically significant differences between them.