Lateral root canals, which often branch from the main root canal system, contain pulp tissue and may harbor pathological processes requiring endodontic intervetion. Effective identification, cleaning, and obturation of these lateral canals are crucial for the long-term success of root canal treatment. This study compares two commonly used obturation techniques: the single-cone technique using gutta-percha with AH Plus Bioceramic® sealer, and the Thermafil® technique with AH Plus® sealer.Standardized training blocks containing artificial root canal and two lateral canals (coronal and apical) were used. All canals were prepared using ProTaper Next® rotary files. Half of the samples were obturated using the single-cone technique with AH Plus Bioceramic® sealer, and the other half with the Thermafil® technique using AH Plus® sealer. Radiographs and photographs were obtained to evaluated whether lateral canals were filled, partially filled, or unfilled, and to identify the material responsible for the filling.Radiographic evaluation demonstrated successful obturation in 90% of coronal lateral canals and 56.7% of apical lateral canals, resulting in an overall success rate of 73%. No statistically significant differences were observed between the single-cone and Thermafil® techniques for either coronal or apical lateral canals (p > 0.05). Photographic assessment showed a non-significant trend toward improved apical filling with Thermafil® (p = 0.063). Coronal canals were significantly more likely to be filled than apical ones (p < 0.001). The presence of gutta-percha combined with sealer significantly increased the filling rate compared to sealer alone, particularly in apical canals treated with Thermafil® (p < 0.001).Although no significant differences were observed between techniques, Thermafil® exhibited a trend toward improved apical filling. Overall, coronal lateral canals were more successfully filled than apical canals, and the combination of gutta-percha and sealer was more effective than sealer alone.