title: Measurement of pressure and flow rates during irrigation of a root canal ex vivo with three endodontic needles.
abstract: OBJECTIVE
  To monitor ex vivo intra-canal irrigation with three endodontic needles (25, 27 and 30 gauge) and compare them in terms of irrigant flow rate, intra-barrel pressure, duration of irrigation and volume of irrigant delivered.
  
  
  METHODS
  A testing system was constructed to allow measurement of selected variables with pressure and displacement transducers during ex vivo intra-canal irrigation with a syringe and three different needles (groups A, B, C) into a prepared root canal. Ten specialist endodontists performed the irrigation procedure. Each operator performed ten procedures with each needle. Data recorded by the transducers were analysed using Friedman's test, Wilcoxon Signed Rank test, Mann-Whitney U-test and Kendall's T(b) test. The level of significance was set to 95%.
  
  
  RESULTS
  Significant differences were detected among the three needles for most variables. Duration of delivery and flow rates significantly decreased as the needle diameter increased, whilst pressure increased up to 400-550 kPa. Gender of the operator had a significant impact on the results. Experience of the operators (years) were negatively correlated to volume of irrigant (all groups), to the duration of delivery (groups A, B) and to the average flow rate (group A).
  
  
  CONCLUSIONS
  Finer diameter needles require increased effort to deliver the irrigant and result in higher intra-barrel pressure. The syringe and needles used tolerated the pressure developed. Irrigant flow rate should be considered as a factor directly influencing flow beyond the needle. Wide variations of flow rate were observed among operators. Syringe irrigation appears difficult to standardize and control.
authors.affiliation: Department of Endodontology, Dental School, Aristotle University of Thessaloniki, Thessaloniki, Greece. chb@dent.auth.gr
authors.forename: C
authors.initials: C
authors.lastname: Boutsioukis
authors.forename: T
authors.initials: T
authors.lastname: Lambrianidis
authors.forename: E
authors.initials: E
authors.lastname: Kastrinakis
authors.forename: P
authors.initials: P
authors.lastname: Bekiaroglou
mesh_terms: D002614:Chelating Agents / Q000737:chemistry; D003786:Dental Pulp Cavity / Q000648:ultrastructure*; D004492:Edetic Acid / Q000737:chemistry; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D009339:Needles; D015588:Observer Variation; D011312:Pressure; D012212:Rheology; D012388:Root Canal Irrigants / Q000737:chemistry*; D018915:Root Canal Preparation / Q000295:instrumentation*; D012737:Sex Factors; D012973:Sodium Hypochlorite / Q000737:chemistry; D013193:Stainless Steel; D013499:Surface Properties; D013594:Syringes; D007507:Therapeutic Irrigation / Q000295:instrumentation; D013997:Time Factors; D014159:Transducers; D014160:Transducers, Pressure
chemical_list: D002614:Chelating Agents; D012388:Root Canal Irrigants; D013193:Stainless Steel; D004492:Edetic Acid; D012973:Sodium Hypochlorite