The aim of this study was to compare the apical sealing ability,evaluating dye penetration in root canals filled with lateral condensationtechnique with the use of a 7/D11 spreader, a finger-spreader and anultrasonic activated tip. 90 distal roots of mandibular first molars wererandomly divided into three groups, each with 30 roots. Additionally wereused 4 roots as positive control and 4 as negative control. The preparedcanals were obturated with lateral condensation technique with sealer andgutta-percha cones condensed with 7/D11 in group 1, finger-spreader ingroup 2 and a tip activated by ultrasound in group 3. The samples wereimmersed in India ink and subsequently submitted to a demineralization andclearing process. The extent of dye penetration was measured using astereomicroscope with software Motic Images Advanced 3.0. The lowestmean leakage values were observed for 7/D11 group and the highest wereobserved for the ultrasound group. The difference between 7/D11 by oneside and finger spreader and ultrasound on the other was statisticallysignificant (p <0.05). Between ultrasonic tip and finger spreader groups thedifference was not significant.Under the conditions of this study it can be concluded that the use of the7/D11 instrument during condensation of gutta-percha showed better sealingability by allowing less leakage of the dye between the interphaseguttapercha-dentin than finger spreader and the ultrasonic tip
