Coronal leakage is now recognized as an important cause of failure of root canal treatment. This pathway of leakage may be affected by the presence or absence of the smear layer that in turn may affect the close adaptation between the root canal filling material and the root canal walls. This may result in subsequent coronal leakage and failure of treatment. The aim of this study was to compare the sealing ability of AH Plus sealer to the canal wall in the presence and absence of the smear layer. Forty five extracted teeth with fully developed apices were selected. The pulp of each tooth was...