Endodontology (Jan 2020)
Fracture resistance of endodontically treated teeth after instrumentation with different nickel titanium systems
Abstract
Aim: To compare the vertical root fractures (VRFs) resistance of teeth instrumented with ProTaper Universal, ProTaper Next, HyFlex CM and HERO Shaper nickel titanium (NiTi) rotary systems and obturated with compatible gutta-percha cones using the single-cone technique. Materials and Methods: The present study was performed in 72 extracted mandibular premolars. After removing the coronal parts of the teeth and determining working length, the roots were mounted in Eppendorf tubes. The samples were divided into five experimental groups, and one control group (n = 12). In Group 1, teeth were instrumented by hand K files; Group 2 ProTaper Universal (PTU); Group 3 HERO Shaper (HS); Group 4 HyFlex CM (HCM); Group 5 ProTaper Next (PTN); and Group 6 (Controls): the root canals were not shaped or filled. After the preparations were completed, roots were obturated with gutta percha. All the mounted samples were subjected to fracture resistance testing. Statistical Analysis: One-way ANOVA test and post hoc Tukey's test at a significance level of P < 0.05. Results: Fracture resistance of hand K file did not differ significantly from, HERO Shaper, HCM, and PTN NiTi rotary files (P = 0.929; P = 0.996; P = 1.000, respectively). PTU showed significantly less fracture resistance than hand K file (0.044). Among all NiTi rotary files, PTN depicted the highest fracture resistance, whereas PTU showed the least fracture resistance with statistically significant difference (P = 0.048). However, PTN did not differ significantly from HERO Shaper and HCM regarding fracture resistance. Conclusion: All rotary files showed similar fracture resistance values to Hand K file group except ProTaper Universal, which demonstrated significantly lower fracture resistance.
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