A comparison of techniques for assessment of coronal dye leakage

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.