title: Effect of needle insertion depth and root canal curvature on irrigant extrusion ex vivo.
abstract: BACKGROUND
  The aim of this study was to evaluate the effect of needle type and insertion depth, apical preparation size, and root canal curvature on irrigant extrusion by using a recently introduced method.
  
  
  METHODS
  Sixteen human teeth with a straight root canal (group A) and 16 with a moderately curved root canal (group B) were sequentially prepared to sizes 25 or 35, .06 taper and mounted on a plastic vial filled with distilled water to simulate a periapical lesion. The vial was either closed or open to the environment. A point-conductivity probe was used to determine the volume of extruded irrigant into the vial. NaOCl was delivered by an open-ended or a closed-ended needle at 1, 3, or 5 mm short of working length. Results were analyzed by two 4-way mixed-design analyses of variance. The level of significance was set to P < .05.
  
  
  RESULTS
  The open-ended needle extruded significantly more irrigant than the closed-ended. Irrigant extrusion decreased as needles moved away from working length or when the apical size was increased. Needle wedging increased extrusion, especially when an open-ended needle was used. Root canal curvature did not have a statistically significant effect on irrigant extrusion.
  
  
  CONCLUSIONS
  Needle type, needle insertion depth, and apical preparation size had a significant effect on irrigant extrusion.
authors.affiliation: Department of Endodontology, Dental School, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Zoi
authors.initials: Z
authors.lastname: Psimma
authors.forename: Christos
authors.initials: C
authors.lastname: Boutsioukis
authors.forename: Eleftherios
authors.initials: E
authors.lastname: Kastrinakis
authors.forename: Leonidas
authors.initials: L
authors.lastname: Vasiliadis
mesh_terms: D000704:Analysis of Variance; D003187:Compliance; D003786:Dental Pulp Cavity / Q000033:anatomy & histology*; D004867:Equipment Design; D005119:Extravasation of Diagnostic and Therapeutic Materials; D006801:Humans; D009339:Needles; D012388:Root Canal Irrigants / Q000009:adverse effects; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods*; D019227:Tooth Apex / Q000033:anatomy & histology
chemical_list: D012388:Root Canal Irrigants