title: Viability and antibacterial efficacy of four root canal disinfection techniques evaluated using confocal laser scanning microscopy.
abstract: BACKGROUND
  Several disinfection techniques have been recently introduced with the main objective of improving root canal disinfection in the inaccessible areas of the root canal system. This in vitro study was done to evaluate the antimicrobial effect and viability of Enterococcus faecalis biofilms using conventional irrigation, EndoActivator (Dentsply, Tulsa Dental, USA), diode laser irradiation and photon-initiated photoacoustic streaming (PIPS).
  
  
  METHODS
  Root canals of 130 single rooted mandibular premolars, standardized to a uniform length of 20 mm were instrumented until finishing file, F1 (Universal Protaper Rotary System, Dentsply, Tulsa Dental Specialties, USA). After smear layer removal and sterilization, five teeth were randomly selected to assure sterility before bacterial inoculation. The remaining 125 samples were contaminated with E. faecalis suspension, incubated for 21 days and divided into five groups (n = 25). In Group 1; untreated group (positive control), the root canals were not subjected to any disinfection procedure. Sampling was performed within the canals and the colony-forming unit count was evaluated for 20 samples. Five samples were selected to visualize the pattern of colonization at Level 1 (4 mm from the apex) and Level 2 (1 mm from the apex) by confocal laser scanning microscopy. Samples in Groups 2-5 namely conventional needle irrigation, EndoActivator, diode laser and PIPS were subjected to their respective disinfection procedures. Postdisinfection sample evaluation criteria was followed for all groups as same as that for Group 1.
  
  
  RESULTS
  Diode laser displayed the highest antibacterial efficacy and least viable bacteria than the other three disinfection techniques.
  
  
  CONCLUSIONS
  Diode laser group showed better antibacterial efficacy and least viable bacteria when compared to conventional needle irrigation, PIPS and EndoActivator groups in minimally instrumented, experimentally infected root canals.
authors.affiliation: Department of Conservative Dentistry and Endodontics, Rajas Dental College, Tirunelveli District, Tamil Nadu, India.
authors.forename: Joan
authors.initials: J
authors.lastname: Mathew
authors.affiliation: Department of Conservative Dentistry and Endodontics, Rajas Dental College, Tirunelveli District, Tamil Nadu, India.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Emil
authors.affiliation: Department of Conservative Dentistry and Endodontics, Rajas Dental College, Tirunelveli District, Tamil Nadu, India.
authors.forename: Benin
authors.initials: B
authors.lastname: Paulaian
authors.affiliation: Department of Conservative Dentistry and Endodontics, Rajas Dental College, Tirunelveli District, Tamil Nadu, India.
authors.forename: Bejoy
authors.initials: B
authors.lastname: John
authors.affiliation: Department of Conservative Dentistry and Endodontics, Rajas Dental College, Tirunelveli District, Tamil Nadu, India.
authors.forename: Jacob
authors.initials: J
authors.lastname: Raja
authors.affiliation: Department of Conservative Dentistry and Endodontics, Rajas Dental College, Tirunelveli District, Tamil Nadu, India.
authors.forename: Jean
authors.initials: J
authors.lastname: Mathew
keywords: Confocal laser scanning microscopy; Enterococcus faecalis; diode laser; disinfection; minimal instrumentation; root canal