title: Ultrasonic monitoring of the effect of sodium hypochlorite on the elasticity of dentine.
abstract: OBJECTIVE
  To determine the change in ultrasonic velocity of dentine after the application of 5% NaOCl.
  
  
  METHODS
  Twenty standardized plano-parallel dentine bars were divided into two groups. Dentine bars were wetted on only one surface. The test group (n = 10) was irrigated with 5% NaOCl, and the control group, (n = 10) with saline. Ultrasonic velocities before and after irrigation were compared to determine the change in the modulus of elasticity. Finally, dentine bars were loaded until failure in a 3-point bending test. Paired t-test and the mean of differences were used to assess the statistical significance between the groups.
  
  
  RESULTS
  The mean ultrasonic velocity decreased by 1.4% after the application of NaOCl; no change was observed for saline. The mean velocity reduction of 49 m s⁻¹ was found to be highly significant (P = 0.004). The ultrasonically derived modulus of elasticity decreased by 2.6% compared to the initial value of 17.8 GPa. However, the observed reduction in elasticity derived from the 3-point bending test was not significant (P = 0.238).
  
  
  CONCLUSIONS
  NaOCl reduced the ultrasonic velocity of dentine and the ultrasonically derived modulus of elasticity.
authors.affiliation: Division of Endodontology, Department of Conservative Dentistry, University of Tübingen, Germany.
authors.forename: C
authors.initials: C
authors.lastname: John
authors.forename: C
authors.initials: C
authors.lastname: Löst
authors.forename: A
authors.initials: A
authors.lastname: Elayouti
mesh_terms: D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging / Q000187:drug effects; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000000981:diagnostic imaging / Q000187:drug effects*; D055119:Elastic Modulus; D004548:Elasticity; D054459:Elasticity Imaging Techniques; D006801:Humans; D018583:Pliability; D012388:Root Canal Irrigants / Q000494:pharmacology*; D012965:Sodium Chloride; D012973:Sodium Hypochlorite / Q000494:pharmacology*; D013314:Stress, Mechanical
chemical_list: D012388:Root Canal Irrigants; D012965:Sodium Chloride; D012973:Sodium Hypochlorite