Background and Aim: Coronal seal is as important as the quality of root canal therapy in treatment success. This study aimed to compare the coronal microleakage of canals filled with Resilon and gutta percha with a glass ionomer coronal barrier .

  Materials and Methods: In this experimental study, the crowns of 64 single-rooted human premolar teeth were cut at the level of CEJ. Root canals were prepared using rotary ProTaper files. The teeth were randomly divided into 4 experimental groups (n=14) and 2 positive and negative control groups (n=8). Root canals of experimental group specimens were filled with gutta percha (groups 1 and 2) or Resilon (groups 3 and 4) using lateral condensation technique. The roots of negative control specimens were filled and all teeth surfaces were sealed with sticky wax. Root canals of positive controls were filled without the application of sealer. Glass ionomer coronal barrier was placed at the orifices in groups 2 and 4. Microleakage of Streptococcus faecalis was evaluated during 90 days. Data were analyzed using Chi square, Log-Rank and Tukey’s tests .

  Results: The degree of microleakage was less in groups with GI coronal barrier. However, this difference was not statistically significant (P>0.05). Time to microleakage in gutta percha+ coronal barrier and Resilon+ coronal barrier groups was significantly less than that in gutta percha and Resilon groups, respectively (P=0.03 ).

  Conclusion: Within the limitations of this study, microleakage occurred in all groups but glass ionomer acted as an effective barrier .