title: Biofilm removal by 6% sodium hypochlorite activated by different irrigation techniques.
abstract: OBJECTIVE
  To compare the removal of biofilm utilizing four irrigation techniques on a bovine root canal model.
  
  
  METHODS
  Fifty dentine specimens (2 × 2 mm) were infected with biofilm. The samples were then adapted to previously created cavities in the bovine model. The root canals were irrigated twice with 2 mL of 6% sodium hypochlorite for 2 min (4 min total). Following initial irrigation, the different treatment modalities were introduced for 60 s (3 × 20 s intervals). The evaluated techniques were needle irrigation, Endoactivator (Dentsply Tulsa Dental, Tulsa, OK, USA), passive ultrasonic irrigation and laser-activated irrigation (photon-induced photoacoustic streaming). The controls were irrigated with distilled water and conventional needle irrigation. Subsequently, the dentine samples were separated from the model and analysed using a scanning electron microscope (SEM). Fifteen operative fields were scanned per block, and SEM pictures were captured. Two calibrated evaluators examined the images and collected data using a four-degree scale. Nonparametric tests were used to evaluate for statistical significance amongst the groups.
  
  
  RESULTS
  The group undergoing laser-activated irrigation using photon-induced photoacoustic streaming exhibited the most favourable results in the removal of biofilm. Passive ultrasonic irrigation scores were significantly lower than both the Endoactivator and needle irrigation scores. Sonic and needle irrigation were not significantly different. The least favourable results were found in the control group.
  
  
  CONCLUSIONS
  Laser activation of 6% sodium hypochlorite significantly improved the cleaning of biofilm-infected dentine followed by passive ultrasonic irrigation.
authors.affiliation: Department of Endodontics, Dental School of Bauru, University of São Paulo, Bauru, Brazil.
authors.forename: R
authors.initials: R
authors.lastname: Ordinola-Zapata
authors.forename: C M
authors.initials: CM
authors.lastname: Bramante
authors.forename: R M
authors.initials: RM
authors.lastname: Aprecio
authors.forename: R
authors.initials: R
authors.lastname: Handysides
authors.forename: D E
authors.initials: DE
authors.lastname: Jaramillo
mesh_terms: D000818:Animals; D018441:Biofilms; D002417:Cattle; D003786:Dental Pulp Cavity; D023421:Models, Animal; D012973:Sodium Hypochlorite / Q000737:chemistry / Q000494:pharmacology*; D007507:Therapeutic Irrigation
chemical_list: D012973:Sodium Hypochlorite
keywords: biofilms; irrigant solutions; laser-activated irrigation; photoacoustic streaming