BACKGROUND To evaluate the voids percentage and the retreatability by different supplementary irrigation techniques of a matched-taper single cone and epoxy resin-based sealer. METHODS A total of 72 single-rooted premolars were prepared and filled with gutta-percha and MM-Seal. The percentage of voids in the whole root canal and each anatomical part were evaluated by Micro-CT scans. After root filling removal, the teeth were randomly allocated (N.=24) to group A, syringe irrigation; group B, Tornado Brush, and group C, ultrasonically activated irrigation and re-scanned to establish the volume of remnant root filling material. The data relative to voids and retreatment techniques were established by the Kruskal-Wallis test. Differences in retreatment time were examined using one-way ANOVA and Tukey's Test (P<0.05). RESULTS No significant difference was found in the voids percentage between the different root-thirds and between the supplementary irrigation groups in the MM-Seal remnants for the whole root canal and each section. In all groups, the coronal region exhibited more remaining material than other sections. CONCLUSIONS MM-Seal showed low voids percentage and its removal was not significantly improved by supplementary irrigation techniques.