BACKGROUND Obturation is a crucial step in dentistry, involving the filling and sealing of a prepared root canal with sealer and core material to prevent bacterial invasion and ensure successful treatment. This study employed scanning electron microscopy to compare the effectiveness of 3 obturation techniques - single-cone technique (SCT), cold lateral compaction technique (CLCT), and continuous-wave technique (CWT) - in sealing dentin to recently introduced root canal bioceramic sealer in 30 extracted mandibular second premolars. The goal was to determine the optimal technique for minimizing gaps at the sealer-dentin interface. MATERIAL AND METHODS Thirty premolars were divided into 3 groups (n=10 each) based on obturation technique: SCT, CLCT, and CWT. All groups used CeraSeal bioceramic root canal sealer. Root samples were sectioned at apical, middle, and coronal thirds, and high-resolution scanning electron microscopy was performed to measure marginal/internal gaps. Data were analyzed using one-way ANOVA and Tukey range test, with P≤0.05 considered statistically significant. RESULTS CWT showed fewer voids at all levels, with non-significant differences within a technique. Among the techniques, SCT had the largest mean gaps at all levels [apical (5.43±0.16), middle (5.28±0.20), coronal (5.73±0.24)], while CWT had the smallest mean gaps [apical (3.02±0.19), middle (2.95±0.14), coronal (2.76±0.15)]. The differences in means between techniques were statistically significant (P≤0.05). CONCLUSIONS CWT obturation with CeraSeal root canal sealer produces fewer marginal gaps at the sealer-dentin interface.