Effect of Two Techniques of Separated File Removal Systems on Dentin Loss and Fracture Resistance of Teeth (In Vitro Study)

Purpose: to evaluate the fracture resistance of teeth after removal of separated files using either the BTR Pen system or Zumax kit, the impact of the retrieval technique on the fracture resistance, and to assess the correlation between the amount of volume lost during retrieval and fracture resistance of teeth. Materials and Methods: sixty mandibular first molar teeth were selected. Teeth were placed in acrylic resin blocks and were randomly assigned into two groups. Group A: the control group (n=20) and Group B: the study group (n=40). In the study group, five mm of ProTaper Next X2 rotary files were separated in the mesiobuccal canals. The study group was divided into two subgroups, 20 each. Group BI: the broken tool remover (BTR) pen system was utilized to retrieve separated instruments and Group BII: the Zumax kit was employed for retrieval of separated instruments. Cone Beam Computed Tomography (CBCT) was taken before and after retrieval for volumetric analysis. Fracture loading test was performed using the universal testing machine. Values were analyzed by SPSS software using F-test (ANOVA) and independent t-test. Results: there was a significant increase (P=0.001) in canal volume in the study groups. Comparing the mean fracture resistance of the three groups, no significant difference among the groups was found (P= 0.384). Conclusions: retrieving separated instruments from the coronal third of the root canal is regarded as a safe procedure and has no impact on tooth fracture resistance.