Objective ·To explore the efficacy of the XP-Endo Shaper (XPS) and Reciproc (RC) engine-driven nickel-titanium file systems in removing root canal fillings, and to provide evidence for clinical application. Methods ·The maxillary first permanent molars were obtained from patients who visited the Department of General Dentistry, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, between March and September 2022, which required tooth extraction due to periodontal disease. A total of 30 mesiobuccal or distobuccal root canals with moderate curvature were selected and randomly divided into the RC file group (control group, n=15) and the XPS file group (experimental group, n=15). All root canals were first negotiated and shaped using M3-PRO nickel-titanium files, followed by root canal obturation with bioceramic paste using the single-cone technique. Then, RC files (R25) were used in the control group, while XPS files were used in the experimental group to remove the root canal obturation. Cone Beam Computed Tomography (CBCT) scans were performed before and after the removal procedures. The time required for obturation removal, the percentage of residual obturation volume, the amount of apical debris extrusion, and the degree of instrument deformation were recorded. Independent-sample t-tests and chi-square test were used to compare the differences between the two groups. Results ·The XPS group required slightly more time (118.87±18.58) s than the RC group (107.93±14.79) s, but the difference between two groups was not statistically significant. The XPS group had a lower percentage of residual obturation volume (7.51±8.06)% compared to the RC group (15.02±14.63)%, but the difference was not statistically significant. The XPS group had significantly less apical debris extrusion (6.15±1.42) mg than the RC group (8.29±2.01) mg, with a statistically significant difference (P=0.002). Both groups exhibited varying degrees of instrument deformation, but yet no instrument separation occurred in either group. Conclusion ·The RC engine-driven nickel-titanium files were slightly more time-efficient in removing root canal fillings, whereas the XPS files achieved a higher canal cleanliness and produced less apical debris extrusion. As there was no significant difference in removal time, and considering the superior cleaning performance and reduced risk of postoperative complications, the XPS file system appears more suitable for removing root canal fillings in moderately curved root canals.