title: Effectiveness of four different final irrigation activation techniques on smear layer removal in curved root canals : a scanning electron microscopy study.
abstract: OBJECTIVE
  The aim of this study was to assess the efficacy of apical negative pressure (ANP), manual dynamic agitation (MDA), passive ultrasonic irrigation (PUI) and needle irrigation (NI) as final irrigation activation techniques for smear layer removal in curved root canals.
  
  
  METHODS
  Mesiobuccal root canals of 80 freshly extracted maxillary first molars with curvatures ranging between 25° and 35° were used. A glide path with #08-15 K files was established before cleaning and shaping with Mtwo rotary instruments (VDW, Munich, Germany) up to size 35/0.04 taper. During instrumentation, 1 ml of 2.5% NaOCl was used at each change of file. Samples were divided into 4 equal groups (n=20) according to the final irrigation activation technique: group 1, apical negative pressure (ANP) (EndoVac); group 2, manual dynamic agitation (MDA); group 3, passive ultrasonic irrigation (PUI); and group 4, needle irrigation (NI). Root canals were split longitudinally and subjected to scanning electron microscopy. The presence of smear layer at coronal, middle and apical levels was evaluated by superimposing 300-μm square grid over the obtained photomicrographs using a four-score scale with X1,000 magnification.
  
  
  RESULTS
  Amongst all the groups tested, ANP showed the overall best smear layer removal efficacy (p < 0.05). Removal of smear layer was least effective with the NI technique.
  
  
  CONCLUSIONS
  ANP (EndoVac system) can be used as the final irrigation activation technique for effective smear layer removal in curved root canals.
authors.affiliation: Post Graduate Student, Department of Conservative Dentistry and Endodontics Meenakshi Ammal Dental College, Chennai, India.
authors.forename: Puneet
authors.initials: P
authors.lastname: Ahuja
authors.affiliation: Department of Conservative Dentistry and Endodontics, Meenakshi Ammal Dental College, Chennai, India.
authors.forename: Suresh
authors.initials: S
authors.lastname: Nandini
authors.affiliation: Professor, Department of Conservative Dentistry and Endodontics, Meenakshi Ammal Dental College, Chennai, India.
authors.forename: Suma
authors.initials: S
authors.lastname: Ballal
authors.affiliation: Professor, Department of Conservative Dentistry and Endodontics, Meenakshi Ammal Dental College, Chennai, India.
authors.forename: Natanasabapathy
authors.initials: N
authors.lastname: Velmurugan
keywords: Root Canal Preparation; Root Canals; Smear Layer; Sodium Hypochlorite