Introduction: The apical vessels may also be severed or damaged enough to interfere with the normal reparative process. Radicular lesions develop when microorganisms of sufficient pathogenicity and number gain access to peri-radicular tissues. Microorganisms may be predominantly resilient to eradication by host defence mechanisms and antimicrobial agents when they are arranging in an extraarticular biofilm. Objectives: The present study aims to compare the apical sealing ability of two materials Mineral trioxide aggregate (MTA) plus and Biodentin as well as to evaluate bacterial microleakage using a bacterial leakage model for 28 days. Methods: Sixty single-rooted extracted permanent teeth were selected. All the teeth should have straight pulp canals were included in the study while the tooth with root caries, multiple canals, lateral radicular canals Calcifications, peri-radicular resorp tive changes excessive curvatures, developmental defects, root fractures, with internal resorption, previously endodontically treated cracks or root defects were excluded from the study. Samples used in this in-vitro study had been extracted for ortho dontic or periodontal reasons. Results: Biodentine and controls on day 1. There was no leakage observed for MTA plus and Biodentine. Only one sample of positive control leaked. The comparison was done using the Kruskal Wallis test and the p-value was found to be 0.392 which was statistically not significant. Biodentine and control groups on day 5. On day 5, 13.33% of MTA plus group leaked (2 out of 15 samples) against 40% of positive controls leaked (6out of 15 samples). Conclusion: The resent study concludes that MTA plus and Biodentine have good apical sealing ability against E.faecalis at 28 days. Biodentine was better in performance than MTA plus in terms of apical sealing for accurately measuring the microleakage and quantify it further in-vitro models can be pursued.