title: The influence of the ultrasonic intensity on the cleaning efficacy of passive ultrasonic irrigation.
abstract: BACKGROUND
  It is not clear whether increasing the ultrasonic intensity would enhance the cleaning efficacy of passive ultrasonic irrigation (PUI) inside a root canal. The aim of this study was to evaluate the effect of the ultrasonic intensity on PUI to remove dentin debris and whether there is any lateral effect beyond the ultrasonic tip.
  
  
  METHODS
  Each of 15 in vitro root canal models with four standard depressions in the apical part of one canal wall were filled with dentin debris and received PUI repeatedly. The most apical depression was localized apically from the ultrasonic tip. The highest intensity was applied in group 1, the lowest intensity was applied in group 3, and syringe irrigation was performed in group 4 as a control. Before and after irrigation, images of the canal wall with depressions were taken and compared. The removal of dentin debris in the depression was categorized as clean or not clean. The data were analyzed by means of the chi-square test. The oscillation amplitude of the ultrasonic file at each intensity was recorded in vitro using time-resolved high-speed imaging.
  
  
  RESULTS
  Group 1 (highest intensity) exhibited significantly better cleaning than all the other groups (P < .05); no significant difference was found between the four levels of the depressions within any of the four groups. High-speed imaging showed that the amplitude of the oscillating file increased as the intensity went up, which leads to a higher velocity of the irrigant around the file.
  
  
  CONCLUSIONS
  Higher ultrasonic intensity resulted in a higher amplitude of the oscillating file and, consequently, enhanced the cleaning efficacy of PUI.
authors.affiliation: Department of Endodontology, University of Amsterdam, Amsterdam, The Netherlands. l.jiang@acta.nl
authors.forename: Lei-Meng
authors.initials: LM
authors.lastname: Jiang
authors.forename: Bram
authors.initials: B
authors.lastname: Verhaagen
authors.forename: Michel
authors.initials: M
authors.lastname: Versluis
authors.forename: Jelmer
authors.initials: J
authors.lastname: Langedijk
authors.forename: Paul
authors.initials: P
authors.lastname: Wesselink
authors.forename: Lucas W M
authors.initials: LW
authors.lastname: van der Sluis
mesh_terms: D003786:Dental Pulp Cavity / Q000473:pathology*; D003804:Dentin / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D009991:Oscillometry; D012212:Rheology; D012388:Root Canal Irrigants / Q000008:administration & dosage*; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods; D013594:Syringes; D007507:Therapeutic Irrigation / Q000295:instrumentation / Q000379:methods; D013997:Time Factors; D014465:Ultrasonics / Q000295:instrumentation
chemical_list: D012388:Root Canal Irrigants