The purpose of this study was to compare the bacterial leakage of root canals obturated with three root canal sealers, using Endodontalis faecalis as a microbial tracer to determine the length of time for bacteria to penetrate through the obturated root canal to the root apex. Seventy-five, single-rooted teeth with straight root canals had the crown cut off at the cementoenamel junction. Root canals were instrumented by a step-back technique. The prepared teeth were randomly divided into 3 groups of 19 teeth each and another 2 groups as positive and negative controls (9 teeth each). The experimental groups were dependent on the sealer used: AH-Plus, Apexit, and Ketac-Endo. The root canals were obturated using a lateral condensation technique. After 24 h the teeth were attached to microcentrifuge tubes with 2 mm of the root apex submerged in Brain Heart Infusion broth in glass test tubes. The coronal portions of the root canal filling materials were placed in contact with E. faecalis. The teeth were observed for bacterial leakage daily for 30 and 60 days. With the chi2 test for comparing pairs of groups at the 0.05 level (p < 0.05), there was no statistical difference between Ketac-Endo and AH-Plus (p > 0.06), but Apexit had significantly higher leakage (p < 0.05) at 30 days. After 60 days there was no statistical difference between Ketac-Endo and Apexit (p > 0.05), but Apexit leaked more than AH-Plus. The conclusion drawn from this experiment was that epoxy resin root canal sealer was found to be more adaptable to the root canal wall and filling material than a calcium hydroxide sealer when bacterial coronal leakage was studied.

Despite an irregular surface morphology and absence of a smear layer, bonding to pulpal floor dentine was weaker than previously reported for cut coronal dentine. The self-etching-priming system bonded more strongly than the 'one-bottle' system.

In terms of subsequent bond strength during restoration, sodium perborate mixed with distilled water appears to be the best intracoronal bleaching agent.

This study was designed to compare different techniques for coronal dye leakage testing. One hundred and fifty extracted human anterior teeth were fully instrumented and randomly divided into two experimental groups of 60 teeth each, plus two groups of 15 teeth each for positive and negative controls. One group was rinsed with 5.25% NaOCl (smear layer intact), whereas the other group was flushed with 17% EDTA and 5.25% NaOCl (smear layer removed). Roots were obturated with gutta-percha using lateral condensation and AH Plus as root canal sealer. Each experimental group was divided into three subgroups of 20 teeth each for three methods of testing coronal dye leakage: passive dye penetration, penetration with vacuum applied, and fluid filtration methods. The teeth were left in 100% humidity at 37 degrees C for 5 days before being immersed in Indian ink for 2 days and cleared. The linear extent of dye penetration was measured. Mean depth of leakage for the groups with the smear layer intact was 2.5 +/- 1.0 mm for passive dye penetration, 6.7 +/- 2.8 mm for vacuum dye penetration, and 3.0 +/- 1.1 mm for fluid filtration dye penetration. In the group in which the smear layer was removed, the mean depths of leakage were: 3.2 +/- 2.1 mm for passive dye penetration, 5.8 +/- 2.8 mm for vacuum dye penetration, and 3.4 +/- 2.1 mm for fluid filtration. The vacuum method resulted in significantly (p < 0.05) more dye penetration than fluid filtration and passive dye penetration. The presence or absence of smear layer had no statistically significant effect (p > 0.05) on any of the leakage testing techniques.