Aims: The aim of this study was to evaluate the effect of passive ultrasonic activation on calcium hydroxide removal from simulated internal root resorption (IRR) cavities at different root levels.
Methods and material: Sixty mandibular canines were prepared and divided into 3 groups to create IRR cavities at apical, middle, coronal root levels. The cavities filled with calcium hydroxide (CH). Specimens were divided into two subgroups according to the technique used for CH removal: Passive ultrasonic activation (PUA), Classic syringe irrigation (CSI). The cavities were photographed with a stereomicroscope, and percentage of remaining CH was measured using digital image analysis software (Image J). Statistical analysis was performed with two-way ANOVA and post-hoc Duncan tests.
Results: PUA removed significantly more CH at apical and middle levels. (p < 0.05) There was no significant difference between PUA and CSI at coronal level. (p > 0.05) In PUA group, the amount of residual CH was the highest at coronal level. (p < 0.05) In CSI group, the amount of residual CH was the highest at apical level. (p < 0.05).
Conclusions: None of the tested technique was able to completely remove CH from the simulated IRR cavities. CH was removed better with PUA than CSI at middle and apical root levels. For both techniques, the best results were obtained at middle root level.
Keywords: Calcium hydroxide removal; endodontics; image analysis; internal root resorption; passive ultrasonic activation.