title: The evaluation of removal of calcium hydroxide paste from an artificial standardized groove in the apical root canal using different irrigation methodologies.
abstract: OBJECTIVE
  To evaluate the capacity to remove a calcium hydroxide (Ca(OH)2) paste from the root canal and to evaluate the efficacy of Ca(OH)2 removal during passive ultrasonic irrigation using either sodium hypochlorite (NaOCl) or water as an irrigant.
  
  
  METHODS
  Sixteen mandibular premolars were used. Each root was prepared to the apical foramen using GT instruments of size 30, 0.06 taper. Each root was split longitudinally. In one half of the root, a groove was cut in the canal wall 2-6 mm from the apex which was then filled with a Ca(OH)2 paste. Subsequently the roots were reassembled. In group 1 (n = 16), the teeth were ultrasonically irrigated using 50 mL 2.0% NaOCl as the irrigant. Group 2 (n = 16) was treated in the same manner as group 1, but using 50 mL water in place of the NaOCl. In group 3 (n = 16), the teeth were irrigated by syringe injection of 50 mL 2.0% NaOCl. The quantity of remaining Ca(OH)2 in the groove was scored and the data analysed with Kruskal-Wallis and Mann-Whitney tests.
  
  
  RESULTS
  The difference in remaining Ca(OH)2 between all groups was statistically significant (P < 0.001). Group 1 had significantly lower scores than group 2 (P < 0.001) and group 3 (P = 0.002), but there was no significant difference between groups 2 and 3 (P = 0.765).
  
  
  CONCLUSIONS
  Passive ultrasonic irrigation with 2% NaOCl was more effective in removing Ca(OH)2 paste from artificial root canal grooves than syringe delivery of 2% NaOCl or water as irrigant.
authors.affiliation: Department of Cariology Endodontology Pedodontology, Academic Centre for Dentistry Amsterdam (ACTA), Amsterdam, The Netherlands. l.vd.sluis@acta.nl
authors.forename: L W M
authors.initials: LW
authors.lastname: van der Sluis
authors.forename: M K
authors.initials: MK
authors.lastname: Wu
authors.forename: P R
authors.initials: PR
authors.lastname: Wesselink
mesh_terms: D002126:Calcium Hydroxide; D017005:Dental Debonding; D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; D018915:Root Canal Preparation / Q000379:methods*; D012973:Sodium Hypochlorite; D018709:Statistics, Nonparametric; D013594:Syringes; D019227:Tooth Apex; D014464:Ultrasonic Therapy; D014867:Water
chemical_list: D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; D014867:Water; D012973:Sodium Hypochlorite; D002126:Calcium Hydroxide