Single-Cone vs. Carrier-Based Root Canal Obturation with a Calcium-Silicate-Based Sealer: An In Vitro µ-CT Analysis

The introduction of calcium-silicate-based sealers has renewed interest in simplified obturation protocols such as the single-cone technique, although warm techniques, including carrier-based obturation, are still considered the gold standard. The aim of this in vitro study was to compare the quality of root canal obturation achieved with single-cone and carrier-based techniques when used with the same calcium-silicate-based sealer. Thirty extracted mandibular molars were prepared using a standardized rotary instrumentation protocol and randomly assigned to two groups (n = 15 each): Group A was obturated using a carrier-based technique (Soft-Core obturators), while Group B was obturated with the single-cone technique. All canals were filled with the same calcium-silicate-based sealer (NeoSEALER Flo). Micro-computed tomography was used to evaluate the number and volume of voids of the obturation. Quantitative analysis showed that Group A exhibited a significantly lower number of voids (9.0 ± 5.0) and reduced total void volume (2.58 ± 0.8 mm³) compared with Group B (22.0 ± 10.1 voids; 4.71 ± 1.1 mm³; <i>p</i> = 0.00002 and <i>p</i> = 0.0026, respectively). Qualitative analysis confirmed that carrier-based obturation achieved a denser and more homogeneous filling, while the single-cone technique showed larger voids mainly in the coronal and middle thirds. Both techniques provided a reliable apical seal. Within the limitations of this in vitro study, carrier-based obturation demonstrated superior overall filling quality compared with the single-cone technique when used with a calcium-silicate-based sealer, particularly in the middle and coronal regions of the root canal.