The effect of tapered master gutta‑percha cone on apical seal of straight and curved root canals prepared with nickel–titanium rotary files

Background: Gutta‑percha has been the predominant root canal filling material which is developed with different taper. Canal obturation fixed with nickel–titanium (NiTi) instruments and tapered gutta‑percha master cone and lateral condensation is advantageous because it is clinically effectual and appears to result in a radiographically acceptable outcome. The aim of this in vitro study was to determine the effect of tapered master gutta‑percha cone on apical seal of straight and curved root canals using NiTi rotary files. Materials and Methods: In this in vitro study total of 130 mandibular molars were selected and divided into six experimental groups (n = 20) based on the degree of root canal curvatures (0°–20°and 20°–40°) and the taper of master cones (0.02, 0.04, and 0.06). The roots were immersed in the bacterial leakage model and monitored daily for a period of 70 days. Data were analyzed using Kaplan–Meier approach, log‑rank test, and Chi‑square tests. P < 0.05 was considered statistically significant. Results: The microleakage in the 0°–20° canal curvature using 0.02‑ and 0.04‑tapered master cones was similar and considerably <0.06‑tapered master cone (P < 0.05). However, the microleakage in the 20°–40° canal curvature using 0.02‑ and 0.04‑tapered master cones was more than 0°–20° and for 0.06‑tapered master cone was <0°–20°, but there was no statistical difference between the use of 0.02‑, 0.04‑, and 0.06‑tapered master cones (P > 0.05). Conclusion: The lateral condensation filling technique using 0.02‑ and 0.04‑tapered master cones is more effective in minimizing microbial leakage in straight canals than 0.06‑tapered master cone.