Tubular sclerosis rather than the smear layer impedes dye penetration into the dentine of endodontically instrumented root canals

Aim To evaluate the effect of different root canal irrigating regimes on dentine penetration of Patent Blue dye. Methodology Eighty extracted single‐rooted human mandibular premolar teeth with narrow root canals were prepared using ProFile instruments. After each instrument, canals were irrigated with 1% sodium hypochlorite. Subsequently, teeth were randomly assigned to receive a 10 mL rinse of aqueous 17% (w/v) ethylenediaminetetraacetic acid or tap water for 2 or 10 min, followed by a final rinse with a 2% Patent Blue dye solution for 2 or 10 min (eight groups, n = 10 teeth per group). Teeth were then horizontally sectioned 3, 6 and 9 mm from the apex. Sections were digitally photographed and dye penetration was calculated as percentage of total dentine area using NIH Image J. Values were compared using one‐way anova and Bonferroni correction with the alpha‐type error set at