فهرست نشریات علمی دسترسی آزاد ایران

Objective: This study aimed to compare the fracture resistance of human mandibular premolar roots after instrumentation with different nickel–titanium (NiTi) rotary systems.Methods: Forty extracted human mandibular premolars were decoronated and randomly assigned to four groups (n=10). Group 1 served as an uninstrumented control, while Groups 2–4 were prepared using different NiTi rotary systems according to the manufacturers’ protocols: One Curve (OC) single-file system (Group 2), XP-Endo Shaper (XPS) single-file system (Group 3), and ProTaper NEXT (PTN) multi-file system (Group 4). All instrumented canals were obturated with gutta-percha and AH Plus sealer using the lateral compaction technique. Vertical fracture resistance was then tested with a universal testing machine. Data were analyzed using one-way ANOVA followed by Tukey’s post hoc test (α=0.05).Results: ANOVA revealed a significant difference in fracture resistance among the groups (P=0.005). The control group (402 ± 115.93 N) showed significantly higher mean fracture resistance compared to all instrumented groups (P < 0.05). Among the instrumented groups, XPS (304 ± 37.47 N) had the highest mean fracture resistance, followed by OC (291 ± 78.37 N) and PTN (288 ± 50.50 N), but these differences were not statistically significant (P > 0.05).Conclusions: Root canal instrumentation with both single-file and multi-file NiTi rotary systems significantly reduced fracture resistance compared to uninstrumented roots. There was no significant difference in fracture resistance between the single-file and multi-file systems, indicating that the single-file approach does not provide an advantage in preserving root strength.