Intra orifice barrier placed over the canal orifices has been recommended to ensure good coronal seal. This in vitro study compared the microbial leakage of E. faecalis bacteria through MTA, Biodentine, Cention –N and Ketac - Silver when used as intra orifice coronal barrier, in an in-vitro experimental set up and also to compare the preferred thickness between 2 mm and 4 mm of intra orifice coronal barrier. Materials and methods: A total of 120 human extracted, single rooted teeth were selected. Decoronation done, access opening done, working length determined, and canals were cleaned and shaped with pro taper file and obturated with sealer and gutta percha using lateral condensation technique. Samples were divided into four experimental groups and two control groups. Approximately 2 mm and 4 mm of Gp was removed from the coronal orifice and restored with respective restorative materials. Teeth were attached in 1.5 ml of eppendorf tube and suspended in 30ml reagent bottle containing BHI broth which was used to check bacterial leakage. Tubes were incubated and checked for turbidity for 30 days. Data were analyzed using chi –squared test between the test groups. Results: Significantly the least number of samples turned turbid in the MTA 4mm group followed by MTA 2 mm, Biodentine 4 mm, 2 mm, Cention - N 4 mm, 2 mm and Ketac –Silver 4 mm, 2 mm showed the maximum turbidity. Conclusion: The MTA is a better intra orifice barrier, followed by Biodentine, Cention-N and Ketac –Silver.