Effect of root canal sealer with bioceramic content applied at different root levels in single-rooted teeth with different apical diameters on root canal filling quality and apical extrusion

Objective: To evaluate the apical extrusion amount and root canal filling percentage of bioceramic root canal sealer applied at different root levels in single-rooted teeth with different apical diameters by micro-computed tomography. Method: 60 human mandibular premolar teeth with a single root and a single canal were included in the study. For standardization, crowns were cut and removed to obtain a root length of 14 ± 1 mm. The teeth were randomly divided into 3 main groups with apical diameters of 25/.04, 25/.06 and 30/.04 (n=20). Then, each main group was randomly divided into 2 subgroups according to the application level of bioceramic root canal sealer (4 and 7 mm from the apex) (n=10). The root canals of the teeth were shaped using rotary files and endomotors. Plastic spheres were placed with cyanoacrylate at the apex of the teeth and embedded in c-type silicone. The spheres in the samples were removed and agar gel was placed in the resulting space. The root canals were filled with bioceramic root canal sealer and gutta-percha compatible with the preparations using the single cone technique. The application tip of the bioceramic root canal sealer was delivered to the canal by adjusting the stopper according to the root level tested in each group. The teeth were kept in the oven for 7 days for the root canal sealer to harden. Then, micro-computed tomography images were taken for the volume of the sealer amount extruded from the apex and the root canal filling percentage. The root canal filling and the apically extruded material of each tooth were subjected to a volumetric analysis using microtomography. After image acquisition and two-dimensional projection, the sections were reconstructed using NRecon software, v.1.7.4.2. CTAn software, v.1.18.4.0 was used to measure the volume of the extruded material in mm3 and to find the filling percentage of the root canals. The filling percentage of the root canals was calculated by dividing the root canal filling volume by the root canal filling and the empty volume in the root canals. In the evaluation of root canal filling percentage data, One-Way ANOVA, Post Hoc Tukey and independent t-test were used. In the evaluation of apical extrusion data, Chi-square test was performed and confirmed with Bonferroni test. Results: No statistically significant difference was found between the groups in terms of root canal filling percentage at 4 mm root level. At 7 mm root level, higher root canal filling percentage was found in 25/.06 apical diameter compared to 25/.04 (P <0.05). No statistically significant difference was found between the groups in the apical extrusion of the sealer applied at 4 mm root level. At 7 mm root level, the lowest amount of apical extrusion was found in teeth with 30/.04 apical diameter (P <0.05). Conclusion: Root canal sealer applied at 7 mm root level showed the most successful results with high root canal filling percentage and minimal apical extrusion in teeth with 30/.04 apical diameter. Application of root canal sealer at 7 mm root level provided a more controlled filling compared to 4 mm and reduced the risk of extrusion.. Keywords: apical extrusion, bioceramic based root canal sealer, root canal filling percentage, root canal treatment, micro-computed tomography.