Evaluation of apically extruded bacteria associated with different nickel-titanium systems

Introduction The aim of this in vitro study was to evaluate the amount of apically extruded bacteria associated with several root canal preparation systems. Methods Forty-four extracted human mandibular premolar root canals were contaminated with an Enterococcus faecalis suspension. After incubation at 37°C for 24 hours, the root canals were instrumented using the Twisted File (SybronEndo, Orange, CA), OneShape (Micro Mega, Besançon, France), and ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland). During instrumentation, apically extruded bacteria were collected into vials containing 0.9% NaCl. The microbiological samples were taken from the vials and incubated in brain-heart agar medium for 24 hours. The numbers of colony-forming units were determined. The data obtained were analyzed using Welch analysis of variance followed by post hoc Games-Howell tests. Results ProTaper Next extruded the highest amount of bacteria, whereas OneShape extruded the least compared with all the other instruments (P =.004). There was a significant difference between OneShape and ProTaper Next in the number of colony-forming units (P =.007) but not between OneShape and Twisted File (P >.05). Conclusions All instrumentation systems extruded bacteria beyond the foramen. The OneShape system extruded less bacteria compared with the Twisted File and ProTaper Next systems. © 2015 American Association of Endodontists

Evaluation of the amount of apically extruded debris during retreatment of root canals filled by different obturation techniques

Objective: To evaluate the amount of apically extruded debris during retreatment (with or without solvent) of root canals filled by two obturation techniques. Materials and Methods: Forty-eight root canals were prepared using ProTaper Universal F3 and filled with Gutta-percha and AH 26 sealer using single cone or lateral condensation techniques. The root canal fillings were removed using ProTaper Universal Retreatment system with or without solvent, and the canals were further prepared with ProTaper F4. The operating time was measured. The debris extruded was collected into preweighed Eppendorf tubes. The dry weight of the extruded debris was calculated by subtracting the weight of the empty tube from that of the tube containing debris. Statistical analysis was performed with two-way analysis of variance test, with Bonferroni correction at a 95% confidence level. Results: There was no statistically significant difference in the amount of extruded debris between the two obturation techniques ( P = 0.332). The mean amount of debris was higher in the nonsolvent groups than the solvent groups, particularly with the single cone technique ( P = 0.013). There was a significant difference between groups with regard to the retreatment time ( P 0.001). Gutta-percha removal took less time in the single cone group than in the lateral condensation group ( P 0.001). Gutta-percha removal in the nonsolvent groups took significantly less time than that in the solvent groups ( P 0.001). Conclusions: The amounts of apically extruded debris were similar in both obturation techniques. A greater amount of apically extruded debris was observed in the nonsolvent groups than the solvent groups