IntroductionThe aim of this study was to compare different obturation techniques in terms of the percentage of gutta-percha filled areas (PGFA), sealer filled areas (PSFA), and voids in straight root canals prepared with different instruments. MethodsOne hundred sixty extracted single-rooted mandibular premolars with straight canals were allocated into 10 groups (n = 16 teeth per group): A, manual instrumentation + lateral compaction (LC); B, Mtwo + GuttaFusion (GF); C, Mtwo + LC; D, Mtwo + single-cone (SC); E, Reciproc + GF; F, Reciproc + LC; G, Reciproc + SC; H, WaveOne + GuttaCore (GC); I, WaveOne + LC; and J, WaveOne + SC. Apical preparation was size 40 in all groups, and AH Plus was used as a sealer. The teeth were sectioned at 2, 4, 6, and 8 mm from the apex. The total area of each canal segment was measured, and the areas were converted to PGFA, PSFA, and voids. Data were subjected to the Kruskal-Wallis and post hoc Dunn tests. ResultsAt the 2-mm level, no significant differences in terms of PGFA and PSFA were obtained (P > .05). At all other levels, canals filled with GC and GF produced significantly higher PGFA and significantly lower PSFA than all other groups (P < .05). At the 2-mm, 4-mm, and 6-mm levels, canals filled with GC and GF showed less voids than group A (P < .05). ConclusionsUnder the conditions of this study, independent of the instrument used for canal preparation, GuttaCore and GuttaFusion produced very homogenous root canal fillings with high PGFA and a low incidence of voids.