title: Penetration of hypochlorites with lowered surface tension into dentine tubules.
abstract: BACKGROUND
  The purpose of the present study was to assess the effect of concentration and temperature of sodium hypochlorite (NaOCl) with added surfactants and time of exposure on its penetration into human dentine.
  
  
  METHODS
  Seventy-five extracted permanent maxillary anterior teeth with single canals were shaped by using ProTaper SX hand-operated instruments. Then teeth were sectioned perpendicular to their long axis. The crowns and apical thirds of all the teeth were removed. The remaining roots were processed into 4-mm-long blocks and stained overnight in crystal violet. One hundred fifty stained blocks were further split into halves and treated by six NaOCl-based solutions from different brands: three solutions added with surfactants (Hypoclean, H6, Chlor-Xtra) and their regular counterparts (5.25%, 6%, <%6NaOCl). The dentine blocks were exposed to the solutions for 2, 5, and 20 minutes at 20° C, 37° C, and 45° C, respectively. The depth of penetration of NaOCl was determined by bleaching of the stain and measured by light microscopy at magnifications of 20x and 40x. Statistical analysis was made by using two way ANOVA and by comparing groups two by two with t-test.
  
  
  RESULTS
  The shortest penetration (130.80±1.92μm) was measured after incubation with 5.25%NaOCl for 2 minutes at 20° C; the highest penetration (375.40±3.05μm) was obtained with Chlor-Xtra for 20 minutes at 45° C. Temperature and exposure time had a significant direct relationship with penetration of sodium hypochlorites with lowered surface tension into dentinal tubules.
  
  
  CONCLUSIONS
  The exposure time and temperature of sodium hypochlorite as well as the addition of surfactants may influence the penetration depth of irrigants into dentinal tubules.
authors.affiliation: Department of Neuroscience, Reproductive and Odontostomatological Sciences, Federico II, University of Naples, Naples, Italy - flaviopalazzi@gmail.com.
authors.forename: Flavio
authors.initials: F
authors.lastname: Palazzi
authors.forename: Gennaro
authors.initials: G
authors.lastname: Sadile
authors.forename: Zahed
authors.initials: Z
authors.lastname: Mohammadi
authors.forename: Massimo
authors.initials: M
authors.lastname: Del Fabbro
authors.forename: Francesco
authors.initials: F
authors.lastname: Riccitiello
mesh_terms: D003804:Dentin / Q000737:chemistry* / Q000648:ultrastructure; D004058:Diffusion; D006801:Humans; D066298:In Vitro Techniques; D009994:Osmolar Concentration; D011897:Random Allocation; D012388:Root Canal Irrigants / Q000493:pharmacokinetics*; D016037:Single-Blind Method; D012973:Sodium Hypochlorite / Q000493:pharmacokinetics*; D013500:Surface Tension; D013501:Surface-Active Agents / Q000494:pharmacology; D013696:Temperature
chemical_list: D012388:Root Canal Irrigants; D013501:Surface-Active Agents; D012973:Sodium Hypochlorite