Background: one of most common procedural errors during clinical procedure is instrument separation during canal preparation, which can compromise apical seal. Whether to remove or bypass the fragment depends on its location and canal anatomy, but often the fragment remains, which can impact apical sealing. The effectiveness of a root canal filling is influenced by the quality of canal preparation, the type of sealer used, and the obturation technique.

AIM: To evaluate and compare the extent of apical microleakage in root canals containing fractured instruments obturated using two different sealers and three different obturation techniques.

Materials and Methods: This in-vitro study was conducted at Maratha Mandal’s Nathajirao G. Halgekar institute of dental sciences and research centre, Belgavi, Karnataka, India over a duration of 2 month from August 2025 to October 2025. Total 36 mandibular molars were decoronated and prepared with hand and rotary files upto size 20. An intentional scratch was made on a #F1 protaper gold rotary file, positioned 3 mm from its tip, using a high-speed handpiece, and it was deliberately fractured at the root apex. Radiographs were taken after the file was fractured to ensure the location of file in the canal, Againwith smaller no. file bypassing of separated instrument was done followed by enlarging the canal with hyflex 20/4%. Then the samples Was randomly divided into 3 groups each group containing 12 sample, Group A: Samples obturated by lateral compaction technique with AH plus and bioceramic sealer, Group B: Samples obturated using the thermoplasticised obturation technique with AH plus and bioceramic sealer, and Group C: Samples obturated using single cone technique with AH plus and bioceramic sealer. Roots were coated with nail varnish, sparing the apical 2 mm and glass ionomer cement was used to seal the coronal opening. The roots were submerged in methylene blue dye for a duration of 48 hours. After rinsing, mesiodistal sectioning of the roots was done using a cutting saw. A stereomicroscope, Magnification: (20X) was used to observe the segments, and the dye penetration depth was measured using an Image Analysis System.

Results: One-way ANOVA and Tukey’s post hoc test was used compare apical microleakage (dye penetration) across all groups, revealing statistically significant differences between sealers and techniques (p < 0.001).

Conclusion: The thermoplastized obturation technique achieved the most effective apical seal, particularly when used with bioceramic sealer.