title: In vitro comparison of passive and continuous ultrasonic irrigation in simulated lateral canals of extracted teeth.
abstract: BACKGROUND
  Complete endodontic system disinfection requires the removal of vital and necrotic pulp tissue, microorganisms, and toxins. The purpose of this study was to compare the effects of 2 ultrasonic irrigation techniques on the penetration of sodium hypochlorite into the main canal and simulated lateral canals of extracted teeth.
  
  
  METHODS
  Two simulated lateral canals each were created 2, 4, and 6 mm from the working length in 60 single-rooted teeth (6 canals/tooth, n = 360). To resemble the clinical situation, a closed system was created in each tooth. The teeth were randomly assigned to 3 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). Samples were evaluated by direct observation of still images recorded under a dental operating microscope. To examine irrigating solution penetration, 20% Chinese ink (Sanford Rotring GmbH, Hamburg, Germany) was added to a 5% sodium hypochlorite solution and delivered into the root canals.
  
  
  RESULTS
  The results showed a significantly higher (P < .05) penetration of irrigant into the lateral canals in the CUI group. PUI and CUI did not differ significantly in solution penetration into the apical thirds of the main canals. The PPI group showed a significantly lower penetration of sodium hypochlorite into the main and lateral canals compared with the CUI and PUI groups.
  
  
  CONCLUSIONS
  CUI as a final rinse significantly increased the penetration of irrigating solution into simulated lateral canals.
authors.affiliation: University of Medicine and Dentistry, Santiago de Compostela, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Castelo-Baz
authors.forename: Benjamín
authors.initials: B
authors.lastname: Martín-Biedma
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Cantatore
authors.forename: Manuel
authors.initials: M
authors.lastname: Ruíz-Piñón
authors.forename: José
authors.initials: J
authors.lastname: Bahillo
authors.forename: Berta
authors.initials: B
authors.lastname: Rivas-Mundiña
authors.forename: Purificación
authors.initials: P
authors.lastname: Varela-Patiño
mesh_terms: D002244:Carbon; D004396:Coloring Agents; D003786:Dental Pulp Cavity / Q000187:drug effects* / Q000473:pathology; D004492:Edetic Acid / Q000008:administration & dosage; D006801:Humans; D008422:Materials Testing; D008853:Microscopy; D009339:Needles; D011312:Pressure; D012388:Root Canal Irrigants / Q000008:administration & dosage*; D018915:Root Canal Preparation / Q000295:instrumentation / Q000379:methods*; D012973:Sodium Hypochlorite / Q000008:administration & dosage*; D013010:Sonication / Q000379:methods; D013594:Syringes; D007507:Therapeutic Irrigation / Q000379:methods; D013997:Time Factors; D019227:Tooth Apex / Q000187:drug effects / Q000473:pathology; D014465:Ultrasonics
chemical_list: D004396:Coloring Agents; D012388:Root Canal Irrigants; C028433:chinese ink; D002244:Carbon; D004492:Edetic Acid; D012973:Sodium Hypochlorite