In this in vitro study, we investigated the effects of the use of two different calcium hydroxide (Ca(OH2)) preparations as an intracanal dressing on the sealing ability of two different sealers were investigated. Eighty-eight freshly extracted, single-rooted maxillary anterior teeth were used. After the root canals were hand-instrumented, they were divided into six groups of 10 each. The root canals were dressed with Ca(OH)(2) paste, either mixed with sterile water (in groups 1 and 2) or with glycerine (in groups 3 and 4). The dressed root canals were incubated in 100% humidity at 37 degrees C for 7 days. In groups 5 and 6, the root canals were not dressed. After the root canal dressings were removed by irrigation with 5.25% NaOCl and remaining with a K-type file, all canals of the experimental groups were obturated with sealer ant gutta-percha using a cold lateral condensation technique. Calciobiotric Root Canal Sealer, (CRCS), (in groups 1, 3 and 5) and Diaket (in groups 2,4 and 6) were used as sealers. All specimens were placed in India ink for 7 days, and the amount of apical leakage was scored. Eight further prepared specimens were dressed with Ca(OH)(2) plus water or Ca(OH)(2) plus glycerine and examined with scanning electron microscopy (SEM) following the removal of dressings. There was a statistical difference in the leakage patterns amongst the 6 experimental groups (P < 0.05). Specimens in group 2 exhibited less leakage than the other experimental groups, except group 4 (P < 0.05). There were no other significant interactions. SEM examination revealed that Ca(OH)(2) crystals were present on the surface of smear layer in both groups where Ca(OH)(2) paste had been placed, but they did not penetrate into the dentinal tubules.