This study aimed to evaluate and compare the efficacy of the S1 reciprocating system and the D-Race retreatment rotary system for filling material removal and the apical extrusion of debris.

Sixty-four freshly extracted maxillary canines were shaped with size 10 and size 15 K-files, instrumented using ProTaper Gold under irrigation with 2.5% sodium hypochlorite (NaOCl), obturated according to the principle of thermo-mechanical condensation with gutta-percha and zinc oxide eugenol sealer, and allowed to set for 3 weeks at 37°C. Subsequently, the teeth were divided into a control group (n = 4), the D-Race rotary instrument group (n = 30), and the S1 reciprocating instrument group (n = 30). After classical retreatment, the canals were subjected to a complementary approach with the XP-Endo Shaper. Desocclusol was used as a solvent, and irrigation with 2.5% NaOCl was performed. Each group was divided into subgroups according to the timing of radiographic readings. The images were imported into a software program to measure the remaining filling material, the apical extrusion, and the root canal space. The data were statistically analyzed using the Z-test and JASP graphics software.

No significant differences were found between the D-Race and S1 groups for primary retreatment; however, using a complementary cleaning method increased the removal of remnant filling (p < 0.05).

Classical removal of canal filling material may not be sufficient for root canal disinfection, although a complementary finishing approach improved the results. Nevertheless, all systems left some debris and caused apical extrusion.