title: Spectrophotometric determination of irrigant extrusion using passive ultrasonic irrigation, EndoActivator, or syringe irrigation.
abstract: BACKGROUND
  Sodium hypochlorite (NaOCl) irrigation is critical to endodontic success, and several new methods have been developed to improve irrigation efficacy (eg, passive ultrasonic irrigation [PUI] and EndoActivator [EA]). Using a novel spectrophotometric method, this study evaluated NaOCl irrigant extrusion during canal irrigation.
  
  
  METHODS
  One hundred fourteen single-rooted extracted teeth were decoronated to leave 15 mm of the root length for each tooth. Cleaning and shaping of the teeth were completed using standardized hand and rotary instrumentation to an apical file size #40/0.04 taper. Roots were sealed (not apex), and 54 straight roots (n = 18/group) and 60 curved roots (>20° curvature, n = 20/group) were included. Teeth were irrigated with 5.25% NaOCl by 1 of 3 methods: passive irrigation with needle, PUI, or EA irrigation. Extrusion of NaOCl was evaluated using a pH indicator and a spectrophotometer. Standard curves were prepared with known amounts of irrigant to quantify amounts in unknown samples.
  
  
  RESULTS
  Irrigant extrusion was minimal with all methods, with most teeth showing no NaOCl extrusion in straight or curved roots. Minor NaOCl extrusion (1-3 μL) in straight roots or curved roots occurred in 10%-11% of teeth in all 3 irrigant methods. Two teeth in both the syringe irrigation and the EA group extruded 3-10 μL of NaOCl.
  
  
  CONCLUSIONS
  The spectrophotometric method used in this study proved to be very sensitive while providing quantification of the irrigant levels extruded. Using the PUI or EA tip to within 1 mm of the working length appears to be fairly safe, but apical anatomy can vary in teeth to allow extrusion of irrigant.
authors.affiliation: Division of Endodontics, University of Minnesota School of Dentistry, Minneapolis, Minneapolis.
authors.forename: Carolina
authors.initials: C
authors.lastname: Rodríguez-Figueroa
authors.affiliation: Division of Endodontics, University of Minnesota School of Dentistry, Minneapolis, Minneapolis.
authors.forename: Scott B
authors.initials: SB
authors.lastname: McClanahan
authors.affiliation: Division of Endodontics, University of Minnesota School of Dentistry, Minneapolis, Minneapolis. Electronic address: bowle001@umn.edu.
authors.forename: Walter R
authors.initials: WR
authors.lastname: Bowles
mesh_terms: D003786:Dental Pulp Cavity / Q000033:anatomy & histology; D005119:Extravasation of Diagnostic and Therapeutic Materials / Q000175:diagnosis*; D006801:Humans; D008422:Materials Testing; D009339:Needles; D011897:Random Allocation; D012388:Root Canal Irrigants / Q000008:administration & dosage* / Q000032:analysis; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D012973:Sodium Hypochlorite / Q000008:administration & dosage / Q000032:analysis; D013010:Sonication / Q000295:instrumentation* / Q000379:methods; D013053:Spectrophotometry / Q000379:methods; D013594:Syringes; D007507:Therapeutic Irrigation / Q000295:instrumentation* / Q000379:methods; D019227:Tooth Apex / Q000033:anatomy & histology; D014464:Ultrasonic Therapy / Q000295:instrumentation* / Q000379:methods
chemical_list: D012388:Root Canal Irrigants; D012973:Sodium Hypochlorite
keywords: Creosol purple; endodontic irrigation; sodium hypochlorite; spectrophotometer