title: Assessment of residual active chlorine in sodium hypochlorite solutions after dissolution of porcine incisor pulpal tissue.
abstract: BACKGROUND
  In previous studies, surfactant-containing Hypochlor brands of sodium hypochlorite showed better tissue solubilizing abilities than Milton; differences not explained by original active chlorine content or presence of surfactant. It was postulated that exhaustion of active chlorine content could explain differences. This study aimed to assess whether Milton's poorer performance was due to exhaustion of active chlorine. Parallel experiments assessed the influence of titration methods, and the presence of chlorates, on active chlorine measurements.
  
  
  METHODS
  Time required to dissolve one or groups of 10 samples of porcine incisor pulp samples in Milton was determined. Residual active chlorine was assessed by thermometric titration. Iodometric and thermometric titration was carried out on samples of Milton. Chlorate content was also measured.
  
  
  RESULTS
  Dissolution of single and 10 pulp samples caused a mean loss of 1% and 3% respectively of active chlorine, not being proportional to tissue dissolved. Thermometric ammonium ion titration resulted in 10% lower values than iodometric titration. Chlorate accounted for much of this difference.
  
  
  CONCLUSIONS
  Depletion of active chlorine is not the reason for differences in tissue dissolving capabilities of Milton. Thermometric ammonium ion titration gives more accurate measurement of active chlorine content than iodometric titration.
authors: School of Dentistry, The University of Queensland.
authors: R M
authors: RM
authors: Clarkson
authors: T K
authors: TK
authors: Smith
authors: B A
authors: BA
authors: Kidd
authors: G E
authors: GE
authors: Evans
authors: A J
authors: AJ
authors: Moule
mesh_terms: D000818:Animals; D002713:Chlorine / Q000032:analysis*; D003782:Dental Pulp / Q000187:drug effects*; D007180:Incisor; D012388:Root Canal Irrigants / Q000737:chemistry*; D012973:Sodium Hypochlorite / Q000737:chemistry*; D013552:Swine; D017186:Titrimetry / Q000379:methods
chemical_list: D012388:Root Canal Irrigants; D002713:Chlorine; D012973:Sodium Hypochlorite
keywords: Dental pulp solubility; iodometric titration; residual active chlorine; sodium hypochlorite; thermometric titration