Abstract The volume of sealer in the apical 1 mm of teeth filled using different techniques was evaluated by micro-commuted tomography (micro-CT). Sixty-four maxillary central incisors were prepared using NiTi rotary instruments. Teeth were randomly distributed into four groups according to root canal sealers (AH Plus, Endofill, Sealapex, and Sealer 26) and subdivided into two subgroups according to the filling techniques (active and passive lateral condensation; n = 8 each). Subsequently, teeth were examined using the 1174 SkyScan micro-CT device. Images were reconstructed using the NRecon software, and the sealer volume (mm3) in the apical region was analyzed using the two-way ANOVA and post-hoc Student-Newman-Keuls test (α = ٠.٠٥). The lowest volume of sealer was observed in teeth filled with Sealapex (0.100 ± 0.009) and Endofill (0.103 ± 0.010). The highest volume was observed in teeth filled with AH Plus (0.112 ± 0.008) and Sealer 26 (0.109 ± 0.018) (p > 0.05). Regarding the filling technique, a lower sealer volume was observed using the active lateral condensation technique compared with that using the passive lateral condensation technique (0.100 ± 0.010 vs. 0.111 ± 0.012) (p < 0.05). Therefore, the lowest volume of sealer was observed in teeth filled with Sealapex and Endofill using the active lateral condensation technique.