apical sealing ability of mineral trioxide aggregate, intermediate restorative material and calcium enriched mixture cement: a bacterial leakage study

introduction:  this  in vitro  study compared the apical sealing ability of three common root end filling materials namely mineral trioxide aggregate (mta), intermediate restorative material (irm) and calcium-enriched mixture (cem) cement using a bacterial leakage model.  methods and materials: the study was conducted on 83 single-rooted human teeth. tooth crowns were cut and root canals were prepared using the step-back technique. apical 3 mm of the roots were cut and a three-mm-deep cavity was prepared using an ultrasonic instrument. the samples were divided into three groups ( n =25) according to the root-end filling material including mta, irm and cem cement. the roots were inserted into cut-end microtubes. after sterilization with ethylene oxide, microtubes were placed in sterile vials containing 10 ml of brain heart infusion (bhi) broth and incubated at 37 ° c and 0.1 ml of enterococcus faecalis  suspension compatible with 0.5 mcfarland standard (1.5×10 8  cell/ ml), which was refreshed daily. this procedure was continued for 70 days. the data were analyzed using the chi-square, kruskal-wallis and log rank tests. the level of significance was set at 0.05.  results:  no significant difference was found in bacterial microleakage among three groups; mta showed slightly (but not significantly) less microleakage than irm and cem. however, the difference in the mean time of microleakage was significant among the groups ( p <0.04) and in mta samples leakage occurred in a longer time than cem ( p <0.012).  conclusion:  the three tested root end filling materials had equal sealing efficacy for preventing bacterial leakage.