Objective: The aim of this article is to evaluate the quality of filling in endodontically treated root canals using the lateral condensation technique and modified lateral condensation technique. Materials and Methods: Thirty-two single-rooted teeth were divided into two groups that were assigned by simple randomization according to the filling technique. Once the endodontic treatment was performed, a periapical radiograph was taken to assess the quality according to the radiographic density and tomography was taken to evaluate the quality according to the tomographic volume of spaces, compared with the post-preparation biomechanical tomography. Finally, we performed a statistical analysis (Student's t-test) to evaluate whether there were differences between the types of filling. Results: Radiographic radiodensity was 182.89 ± 9.81 and 186.72 ± 6.97 HU for teeth treated with the lateral condensation technique and modified lateral condensation technique, respectively. The void volume was 3.75 ± 2.35 and 2.43 ± 1.18 mm 3 for teeth treated with the lateral condensation technique and modified lateral condensation technique, respectively. Conclusion: No significant differences were found between the techniques for both filling quality parameters.