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 periradicular tissues. When microorganisms are competent to colonize in an extraarticular biofilm, they may be principally resistant to abolition by host defence mechanisms and antimicrobial agents. Objective: To compare the apical sealing ability of two materials MTA plus andBiodentin as well as to evaluate bacterial microleakage using a bacterial leakage model for 28 days. Methods: Sixtysingle 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, periradicular resorptive changes excessive curvatures, developmental defects, root fractures, with internal resorption, previously end odontically treated cracks or root defects were excluded from the study. Samples used in this in vitro study had been extracted for orthodontic or periodontal reasons. Results: Biodentineand 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. Biodentineand control groups onday5.Onday5,13.33%ofMineral trioxide aggregate (MTA)plus group leaked(2 out of 15 samples) against 40% of positive controls leaked (6 out of 15 samples). Conclusion: The resent study concludes that MTA plus and Biodentinehave good apical sealing ability against E.faecalisat 28days. Biodentinewas 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.