title: Effects of 2% chlorhexidine and 5.25% sodium hypochlorite on gutta-percha cones studied by atomic force microscopy.
abstract: OBJECTIVE
  To compare the effects of 2% chlorhexidine (CHX) and 5.25% sodium hypochlorite (NaOCl) on gutta-percha (GP) cone structure using atomic force microscopy (AFM).
  
  
  METHODS
  Two standardized GP cones were sectioned 3 mm from the tip, attached to a glass base and immersed in 2% CHX or 5.25% NaOCl for 1, 5, 10, 20 and 30 min. Untreated GP cones were used as control. Topography and elasticity analyses were performed on 12 different regions located between 1 and 2 mm from the tip. Root mean square (RMS) parameters for contact mode imaging and force modulation microscopy variations were measured. The differences between RMS values were tested by anova with Fisher's protected LSD test for multiple comparisons.
  
  
  RESULTS
  There was no deterioration in the topography and physical properties studied when 2% CHX was used in comparison with the control (P < 0.05). The RMS parameter for topography increased after 10 min of 5.25% NaOCl exposure in comparison with the control (P < 0.05). In addition, 5.25% NaOCl increased the elasticity of the GP cone after an immersion time of 1 min in comparison with the control (P < 0.05).
  
  
  CONCLUSIONS
  Two per cent CHX did not change GP cone structure following up to 30 min exposure. Conversely, 5.25% NaOCl caused elastic changes after 1 min exposure.
authors.affiliation: Department of Genetics and Morphology, Institute of Biology, University of Brasília, Brasília, Brazil.
authors.forename: C R A
authors.initials: CR
authors.lastname: Valois
authors.forename: L P
authors.initials: LP
authors.lastname: Silva
authors.forename: R B
authors.initials: RB
authors.lastname: Azevedo
mesh_terms: D002710:Chlorhexidine; D004548:Elasticity; D006171:Gutta-Percha; D008422:Materials Testing; D018625:Microscopy, Atomic Force; D012388:Root Canal Irrigants; D012973:Sodium Hypochlorite; D013499:Surface Properties
chemical_list: D012388:Root Canal Irrigants; D006171:Gutta-Percha; D012973:Sodium Hypochlorite; D002710:Chlorhexidine