title: Effect of maintaining apical patency on irrigant penetration into the apical two millimeters of large root canals: an in vivo study.
abstract: BACKGROUND
  Factors such as complex root canal anatomy and the vapor lock phenomenon have been shown to limit the penetration of irrigating solutions into the apical third in both in vivo and in vitro studies involving small and wide canals. Hence, the aim of this study was to determine whether the use of a patency file is related to the presence of a radiopaque irrigating solution in the apical 2 mm of large human root canals.
  
  
  METHODS
  Forty-three large human root canals were randomly divided into 2 groups. Apical patency was maintained in 1 group (P, n = 22) during shaping and cleaning procedures with a no. 10 K-file 1 mm beyond the working length (WL) but not in the other group (no patency [NP], n = 21). In both groups, the canals were shaped with the K3 system. Irrigation was performed with 1 mL of a solution prepared with a radiopaque contrast medium and 5.25% sodium hypochlorite. Digital images were taken, and 2 calibrated readers determined the presence or absence of the irrigating solution in the apical 2 mm of the root canals.
  
  
  RESULTS
  There were significantly more canals with irrigant in the apical 2 mm when apical patency was maintained with a no. 10- Kfile 1 mm beyond the WL than when apical patency was not maintained throughout the cleaning and shaping procedures (P = .04).
  
  
  CONCLUSIONS
  Maintaining apical patency improves the delivery of irrigants into the apical third of large human root canals.
authors.affiliation: University of Tlaxcala, Tlaxcala, Mexico. jveraro@yahoo.com.mx
authors.forename: Jorge
authors.initials: J
authors.lastname: Vera
authors.forename: Erick M
authors.initials: EM
authors.lastname: Hernández
authors.forename: Mónica
authors.initials: M
authors.lastname: Romero
authors.forename: Ana
authors.initials: A
authors.lastname: Arias
authors.forename: Lucas W M
authors.initials: LW
authors.lastname: van der Sluis
mesh_terms: D016009:Chi-Square Distribution; D003287:Contrast Media / Q000008:administration & dosage; D003790:Dental Pulp Necrosis / Q000628:therapy; D006801:Humans; D011671:Pulpitis / Q000628:therapy; D011859:Radiography; D012388:Root Canal Irrigants / Q000008:administration & dosage*; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods*; D016037:Single-Blind Method; D012973:Sodium Hypochlorite / Q000008:administration & dosage; D019227:Tooth Apex / Q000033:anatomy & histology / Q000000981:diagnostic imaging
chemical_list: D003287:Contrast Media; D012388:Root Canal Irrigants; D012973:Sodium Hypochlorite