Micro-CT evaluation of calcium hydroxide removal through passive ultrasonic irrigation associated with or without an additional instrument

Abstract

Aim: To use computerized microtomography (micro-CT) to evaluate the efficacy of passive ultrasonic irrigation (PUI), with or without an additional file (F5), in removing calcium hydroxide medication.

Methodology: The root canals of single-rooted human teeth were prepared with a ProTaper(®) F4 file (Dentsply Maillefer) and filled with calcium hydroxide/propylene glycol 400 paste. After 30 days of storage under 100% humidity, the teeth were divided into four groups (n = 8) according to the removal technique: passive ultrasonic irrigation (PUI) only, additional file only (file F5), PUI + additional file and master apical file only (F4, control). The specimens were scanned (SkyScan 1174, resolution: 14.36 μm) after chemomechanical preparation, 30 days after the application of Ca(OH)2 paste and following its removal. The percentage of medicament remaining was calculated in terms of total canal volume and medicament volume after storage, based on microtomographic images. Data were analysed using three-way anova/Tukey's test or Kruskal-Wallis/Student-Newman-Keuls test (alpha: 5%).

Results: The use of PUI resulted in lower Ca(OH)2 residue volumes (3.7%) compared to when PUI was not used (6.4%; P < 0.001). The use of the additional file did not significantly influence the percentage of remaining Ca(OH)2 . The percentage of Ca(OH)2 residue was greater in the apical region (6.4%) than in the cervical region (3.8%; P < 0.01).

Conclusions: The use of PUI resulted in more effective Ca(OH)2 paste removal relative to the control regardless of the use of the additional file. The apical region had the highest residue volumes in all techniques.

Keywords: calcium hydroxide; irrigation; microtomography; ultrasound.