Methods: 72 bovine incisor root canals were prepared. They were randomly divided into 6 groups of 12. Canals in one group were just obturated with Resilon filling material, without any EDTA rinsing or laser irradiation as control. In the second group, canals were rinsed with EDTA only, 12 canals irradiated with Nd:YAG laser (1.5 W, 15 Hz) only as the third group and other 12 canals received both mentioned treatments as 4th group. 12 canals with no EDTA rinsing but Er,Cr:YSGG and Nd:YAG lasers irradiation counted as the 5th group. The last twelve canals were treated using all three procedures. Obturation with Resilon root filling material was done by the same investigator. Also, roots were covered by polish except apical parts. After dye penetration process during 5 days as stimulation of apical leakage condition in incubator, histological measurements were done. The extent of leakage was scored as following: penetration of dye measured less than 500 um, between 500 and 1000 um, and more than 1000 um (1 mm). Data analysis was made by Stat view software and the extent of leakage in each group was investigated in both vertical and horizontal cuts. Kruskal-Wallis test was used to determine the significance of leakage differences between groups.
Results: Microleakage in all samples was less than 1 mm. The group with EDTA and both lasers showed less leakage (P<0.5). No significant difference was resulted between other treatment modalities.
Conclusions: Resilon showed very low leakage, especially when canals were rinsed with EDTA and lased.