To compare the volume of voids in oval canals obturated with single cone and bioceramic sealer (SCBC), single cone with lateral condensation or Guttacore by means of micro- computed tomography analysis. To measure the obturation time used for each technique.65 uni-radicular teeth with an oval canal were selected. Canals were shaped with Protaper Next and divided into three groups according to the tested obturation technique. The time taken to obturate the canals was recorded. Each specimen was scanned using micro-CT at a voxel resolution of 25 µm. The volume of detected voids and volume of obturated canal was calculated in relation to the total volume. Voids were classified according to their location in the radicular thirds. 2D images obtained were used to calculate the percentage of filled area and percentage of voids. ANOVA test was used to assess significant differences in voids detected in the root thirds and obturation time. Multiple comparisons were made with the Bonferroni test. To analyze the root thirds Kruskal-Wallis was used and for pairwise comparisons Mann-Whitney with Bonferroni modification.The highest percentage of void volume and void area was found in the single cone group with lateral condensation technique. These differences were significant in the apical third (p<0,01). SCBC was significantly faster (p<0.001).The three-obturation techniques achieved low void rates. SCBC had the least number of voids and was the fastest obturation technique. Clinical Relevance: In oval canals the quality of obturation carried out with these techniques were suitable and clinically acceptable. SCBC was the most efficient obturation technique. Key words:Bioceramic sealer, Oval canals, Single cone technique, Root canal filling, Micro-CT analysis, Guttacore Obturator.