comparison of apical leakage in leteral condensatsion with and without tug-back with Two types of root canal sealers

in order to deermine the effect of root canal cealer on microleakage of obturated root canal by lateral condensation technique(LCT) with and without tug-back(TB).seventy exteracted single root canal teeth were examined.after preparation of root canal with step-back technique,teeth were divided to six groups as follows:5 teeth as positive control group that obturated by LCT with gutta-perch ithout sealer.5 teeth as negative control group in which entire root surfaces and apical foramen coated with nail varnish,and four experimental groups(each group consisted of 15 teeth).hroup I ZOE with TB.group II ZOE without TB.group III roth sealer with TB. and group IV roth sealer without TB.then the teeth were immerssed in pelikan ink for 72 hours and weparated in two peices through vertical long axis.stereomicroscope observation showed that tb groups (I &III) have statistically less microleakage then non TB groups (II&IV) (P<0.0001).there was no significant diffeernces between two TB groups.results also showed no relationship between root canal sealer and apical leakage with and without TB in both type of sealer.