title: An initial investigation of the electrochemical dissolution of fragments of nickel-titanium endodontic files.
abstract: BACKGROUND
  A recent study presented the concept of an electrochemical-induced dissolution technique of fractured instruments. The purpose of this study was to test the ability to dissolve embedded fragments of K3 nickel-titanium (NiTi) files. The surface of the fragment exposed to the electrolytic solution was the main parameter evaluated as an interfering factor on the dissolution process.
  
  
  METHODS
  Three types of K3 NiTi 30.06 file fragments were produced, resulting in different exposed cross-section areas. Anodic current was recorded and used as a reference to evaluate the dissolution process of the fragments. Analysis of variance (P < .05) was used to compare the total electrical charge obtained from current versus time records among the fragments of the 3 groups. Radiographic analysis was carried out before and after the tests to observe the extension of dissolution achieved.
  
  
  RESULTS
  The total electrical charge values generated during the tests evidence a statistical difference among the 3 groups of fragments (analysis of variance, P < .05). The larger is the diameter of the exposed surface cross section, the higher is the total value of electrical charge. The radiographic images obtained before and after the tests showed a significant reduction of the fragment length as a result of the polarization imposed.
  
  
  CONCLUSIONS
  The results presented here showed that it is possible to obtain a significant dissolution of K3 NiTi endodontic instrument fragments. The diameter of the surface of fragment exposed to the medium affects the current levels used to promote the dissolution.
authors.affiliation: Department of Endodontics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Fabiola
authors.initials: F
authors.lastname: Ormiga
authors.forename: José Antônio
authors.initials: JA
authors.lastname: da Cunha Ponciano Gomes
authors.forename: Marcos Cesar Pimenta
authors.initials: MC
authors.lastname: de Araújo
authors.forename: Alexandre Ormiga Galvão
authors.initials: AO
authors.lastname: Barbosa
mesh_terms: D003722:Dental Alloys / Q000737:chemistry*; D004560:Electricity; D055664:Electrochemical Techniques / Q000295:instrumentation; D004566:Electrodes; D004572:Electrolysis / Q000379:methods; D004573:Electrolytes / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry*; D011048:Polarography; D011199:Potentiometry; D018915:Root Canal Preparation / Q000295:instrumentation*; D012995:Solubility; D013499:Surface Properties; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*
chemical_list: D003722:Dental Alloys; D004573:Electrolytes; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium