Materials and methods. Following root canal filling in 70 extracted human single-rooted premolar teeth, the apical 3 mm of their root-ends was resected the root-end cavities with depths of 1, 2 and 3 mm were prepared by ultrasonic retrotips and filled with CEM cement. After setting of cement, the roots were immersed in 2% Rhodamine B and the dye leakage was measured under stereomicroscope (×16) using Image J software. The data were analyzed by one-way ANOVA and Bonferroni post hoc tests at 5% significance level. 

Results. The means and standard deviations of dye penetration in the 1, 2, and 3 mm groups were 3395.5 ± 1893.4, 3410.4 ± 1440.5, and 2581.6 ± 1852.9 µm, respectively. The one-way ANOVA analysis indicated significant differences (P < 0.001) however, the Bonferroni post hoc test revealed that only the positive control group differed significantly from the experimental groups (P < 0.001). 

Conclusion. The findings demonstrated CEM cement to have an adequate root-end sealing ability in 3-mm thickness.