SummaryThe effect on coronal leakage of the use of either a single gutta‐percha cone or cold lateral condensation of gutta‐ percha, with a glass ionomer sealer cement was studied. In addition, the effect of the removal of the smear layer was also determined. Eighty‐eight single‐rooted teeth were prepared chemomechanically using hand files, with the balanced force technique. Lubrication was provided by either Hibiscrub (maintaining the smear layer) or an EDTA ‐containing paste (to remove the smear layer). Copious irrigation was carried out with 2.2 sodium hypochlorite.The teeth were allocated randomly to four groups of 20 teeth each, the remaining eight teeth served as controls. Two groups of teeth, one with and one without smear layer, were obturated with either a single gutta‐ percha cone or cold laterally condensed gutta‐percha, with Ketac Endo as the sealer. The teeth were stored for 6 weeks, thermocycled, and the extent of coronal leakage determined for each group after immersion in India ink for 90 h. The teeth were demineralized, dehydrated and immersed in methyl salicylate, which rendered them transparent. Linear measurement of maximum dye penetration was recorded. The mean depth (+ SD) of leakage for the groups in which the smear layer was left intact was 1.68mm (+0.38) for the single cone (Al) and 2.29 mm (+ 1.58) for lateral condensation (Bl). When the smear layer was removed the mean depth of leakage For the single cone group (A2) was 2.04 mm (+ 0.73) and 2.37 mm (+ 1.70) for the laterally condensed group (B2).There was no significant difference in coronal leakage between the gr
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