title: Evaluation of irrigant flow in the root canal using different needle types by an unsteady computational fluid dynamics model.
abstract: BACKGROUND
  The aim of this study was to evaluate the effect of needle tip design on the irrigant flow inside a prepared root canal during final irrigation with a syringe using a validated Computational Fluid Dynamics (CFD) model.
  
  
  METHODS
  A CFD model was created to simulate the irrigant flow inside a prepared root canal. Six different types of 30-G needles, three open-ended needles and three close-ended needles, were tested. Using this CFD model, the irrigant flow in the apical root canal was calculated and visualized. As a result, the streaming velocity, the apical pressure, and the shear stress on the root canal wall were evaluated.
  
  
  RESULTS
  The open-ended needles created a jet toward the apex and maximum irrigant replacement. Within this group, the notched needle appeared less efficient in terms of irrigant replacement than the other two types. Within the close-ended group, the side-vented and double side-vented needle created a series of vortices and a less efficient irrigant replacement; the side-vented needle was slightly more efficient. The multi-vented needle created almost no flow apically to its tip, and wall shear stress was concentrated on a limited area, but the apical pressure was significantly lower than the other types.
  
  
  CONCLUSIONS
  The flow pattern of the open-ended needles was different from the close-ended needles, resulting in more irrigant replacement in front of the open-ended needles but also higher apical pressure.
authors.affiliation: Department of Endodontology, Dental School, Aristotle University of Thessaloniki, Thessaloniki, Greece. Amsterdam, The Netherlands. chb@dent.auth.gr
authors.forename: Christos
authors.initials: C
authors.lastname: Boutsioukis
authors.forename: Bram
authors.initials: B
authors.lastname: Verhaagen
authors.forename: Michel
authors.initials: M
authors.lastname: Versluis
authors.forename: Eleftherios
authors.initials: E
authors.lastname: Kastrinakis
authors.forename: Paul R
authors.initials: PR
authors.lastname: Wesselink
authors.forename: Lucas W M
authors.initials: LW
authors.lastname: van der Sluis
mesh_terms: D019295:Computational Biology / Q000379:methods; D003786:Dental Pulp Cavity; D003799:Dental Stress Analysis; D004867:Equipment Design; D006801:Humans; D006874:Hydrostatic Pressure; D009339:Needles; D012212:Rheology; D012388:Root Canal Irrigants / Q000008:administration & dosage; D033081:Shear Strength; D007507:Therapeutic Irrigation / Q000295:instrumentation
chemical_list: D012388:Root Canal Irrigants