Comparative Evaluation of Apical Sealing Ability Following Canal Preparation with Different Instrumentation Techniques

Abstract

Background: Success in root canal therapy is dependent on effective cleaning, shaping, and establishment of a fluid tight apical seal. Instrumentation techniques significantly influence canal morphology and the quality of obturation. Aim: To evaluate and compare the apical sealing ability of obturations after canal preparation with different instrumentation techniques. Materials and Methods: In this in vitro study -Forty extracted mandibular premolars with single canals were standardized to 14 mm root length and randomly assigned to four groups (n=10 each). Group 1 – Step back technique with stainless steel hand files; Group 2 – Modified step back technique with hand files; Group 3 – Crown down technique with greater taper manual NiTi files; Group 4 – Crown down technique with greater taper rotary NiTi files. Following cleaning and shaping, all canals were obturated with gutta-percha and bioceramic sealer by lateral condensation. Coronal access was sealed with glass ionomer cement, and samples were stored at 37°C for 24 hours. Root surfaces were coated with varnish except for the apical 3 mm and immersed in 1% methylene blue dye for 72 hours. Longitudinal sections were examined under stereomicroscope at 30× magnification, and dye penetration was measured using ImageJ software. Data were statistically analyzed with ANOVA and Tukey’s test. Results: Mean dye penetration was highest in Group 1 (1.37 ± 0.24 mm), followed by Group 2 (1.06 ± 0.32 mm), Group 3 (0.78 ± 0.18 mm), and lowest in Group 4 (0.62 ± 0.16 mm). Significant differences were observed between step back and crown down groups (p < 0.05). No significant difference was noted between manual and rotary crown down groups. Conclusion: Crown down instrumentation using greater taper NiTi files provided superior apical sealing compared to step back methods. Incorporating coronal pre-flaring and progressive taper preparation enhances obturation quality. Both manual and rotary crown down techniques are effective, though rotary instruments improve efficiency.