Objectives: The purpose of this study was to compare the efficiency in the removal of smear layer in the apical third using two different techniques. Methods: There were used 20 human maxillary central incisor divided in two groups with 10 samples each. Group A: with a thin syringe (multiflex Diadent) the root canal was irrigated for the period of 30 seconds with 10% citric acid solution, positioned at 3mm without moving the syringe, from the root apex; Group B: The same technique was used, but in this procedure there was used longitudinal movements in and out of the root canal with a range between 3 to 7 mm from the root apex. The samples were prepared for SEM(2000x) observation. After that the number of dentine tubules were counted, identifying obliterated and non obstructed ones, in the photomicrographs obtained. Results: The percentage of non obstructed canals or no were submitted to Mam-Whitney statistical test, showing that Group B presented a larger percentage of non obstructed canal tubules.

Conclusions: After the result analysis we could conclude that the longitudinal movements applied while irrigating the root canal turn the smear-layer removal more efficient.