Background: Several techniques have been proposed for root canal filling. New rotary files, with non-standardized taper, are appearing, so, points adapted to the taper of the last instrument used to prepare the canal can help in the obturation process. The aim of this study is to assess the sealing ability of different root canal filling techniques. Material and Methods: Root canals from 30 teeth were shaped with Mtwo and divided in three groups; A, standard lateral condensation with size 35 and 20 gutta-percha points; B, standard lateral condensation and injected gutta-percha; C, single gutta-percha point (standardized 35 Mtwo), continuous wave technique and injected gutta- percha. Root surfaces were covered with nail varnish, except for the apical 2 mm, and submerged in a NO 3 Ag 2 solution; apical stain penetration was measured in mm. Data were compared using the Kruskal-Wallis test with a 90% confidence interval. Results: A and B groups showed stain leakage in the 90% of the cases, whereas it was of 80% for group C. Stain leakage intervals were 1-5 mm for groups A and B and 1-3 mm for group C. There were no statistically significant differences between the three studied groups ( p >.05). Conclusions: All the analyzed root canal filling techniques showed some apical stain leakage, without significant differences among them