title: Micro-CT evaluation of calcium hydroxide removal through passive ultrasonic irrigation associated with or without an additional instrument.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
authors.affiliation: School of Dentistry, Federal University of Pará, Belém, Brazil.
authors.forename: L J M
authors.initials: LJ
authors.lastname: Silva
authors.affiliation: School of Dentistry, Federal University of Pará, Belém, Brazil.
authors.forename: O F
authors.initials: OF
authors.lastname: Pessoa
authors.affiliation: Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
authors.forename: M B G
authors.initials: MB
authors.lastname: Teixeira
authors.affiliation: Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
authors.forename: C H
authors.initials: CH
authors.lastname: Gouveia
authors.affiliation: Department of Biomaterials and Oral Biology, School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors.forename: R R
authors.initials: RR
authors.lastname: Braga
mesh_terms: D002126:Calcium Hydroxide / Q000737:chemistry*; D006801:Humans; D066298:In Vitro Techniques; D019946:Propylene Glycol / Q000737:chemistry; D012387:Root Canal Filling Materials / Q000737:chemistry*; D007507:Therapeutic Irrigation / Q000379:methods*; D013997:Time Factors; D014465:Ultrasonics; D055114:X-Ray Microtomography
chemical_list: D012387:Root Canal Filling Materials; D019946:Propylene Glycol; D002126:Calcium Hydroxide
keywords: calcium hydroxide; irrigation; microtomography; ultrasound