title: In vitrocomparison of passive and continuous ultrasonic irrigation in curved root canals.
abstract: BACKGROUND
  The efficacy of endodontic irrigation procedures can be compromised by the complexity of the root canal system. Delivering irrigants to the apical third of curved canals presents a particular challenge to endodontists. This study compared the effects of two ultrasonic irrigation techniques on the penetration of sodium hypochlorite into the main canal and simulated lateral canals of curved roots in extracted teeth.
  
  
  METHODS
  Two sets of simulated lateral canals were created at 2, 4, and 6 mm from the working length in 60 single-rooted teeth (6 canals/tooth, n = 360 canals). The teeth were randomly divided into three experimental irrigation groups: group 1 (n = 20), positive pressure irrigation (PPI); group 2 (n = 20), passive ultrasonic irrigation (PUI); and group 3 (n = 20), continuous ultrasonic irrigation (CUI). To assess the irrigation solution penetration, 20% Chinese ink (Sanford Rotring GmbH, Hamburg, Germany) was added to a 5% sodium hypochlorite solution and delivered into the curved root canals. The penetration of contrast solution into the simulated lateral canals was scored by counting the number of lateral canals (0-2) penetrated to at least 50% of the total length.
  
  
  RESULTS
  The CUI group showed significantly higher (P< 0.05) irrigant penetration into the lateral canals and into the apical third of the main canals. The PPI group showed significantly lower sodium hypochlorite penetration (P< 0.001) into the main and lateral canals compared with that in the CUI and PUI groups. Significantly higher irrigant penetration was observed in the PUI group than the PPI group.
  
  
  CONCLUSIONS
  Using CUI as the final rinse significantly increased the penetration of irrigant solution into the simulated lateral canals and apical third of curved roots.Key words:Continuous ultrasonic irrigation, curved root canals, passive ultrasonic irrigation, positive pressure irrigation, root canal irrigation.
authors.affiliation: DDS, PhD, University of Santiago de Compostela, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Castelo-Baz
authors.affiliation: PhD, University of Santiago de Compostela, Spain.
authors.forename: Purificación
authors.initials: P
authors.lastname: Varela-Patiño
authors.affiliation: PhD, University Vita-Salute San Raffaele of Milan, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Cantatore
authors.affiliation: DDS, University of Santiago de Compostela, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Domínguez-Perez
authors.affiliation: PhD, University of Santiago de Compostela, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Ruíz-Piñón
authors.affiliation: DDS, University of Santiago de Compostela, Spain.
authors.forename: Ramón
authors.initials: R
authors.lastname: Miguéns-Vila
authors.affiliation: PhD, University of Santiago de Compostela, Spain.
authors.forename: Benjamín
authors.initials: B
authors.lastname: Martín-Biedma