title: The effect of urea on the corrosion behavior of different dental alloys.
abstract: OBJECTIVE
  Intraoral corrosion of dental alloys has biological, functional, and esthetic consequences. Since it is well known that the salivary urea concentrations undergo changes with various diseases, the present study was undertaken to determine the effect of salivary urea concentrations on the corrosion behavior of commonly used dental casting alloys.
  
  
  METHODS
  Three casting alloys were subjected to polarization scans in synthetic saliva with three different urea concentrations.
  
  
  RESULTS
  Cyclic polarization clearly showed that urea levels above 20 mg/100 ml decreased corrosion current densities, increased the corrosion potentials and, at much higher urea levels, the breakdown potentials.
  
  
  CONCLUSIONS
  The data indicate that elevated urea levels reduced the corrosion susceptibility of all alloys, possibly through adsorption of organics onto the metal surface. This study indicates that corrosion testing performed in sterile saline or synthetic saliva without organic components could be misleading.
authors: Department of Prosthodontics, Istanbul University, Faculty of Dentistry, 2nd Floor, Capa - 34390, Istanbul, Turkey.
authors: Onur
authors: O
authors: Geckili
authors: Hakan
authors: H
authors: Bilhan
authors: Tayfun
authors: T
authors: Bilgin
authors: J
authors: J
authors: Anthony von Fraunhofer
mesh_terms: D000327:Adsorption; D017554:Carbon Compounds, Inorganic / Q000737:chemistry; D002858:Chromium Alloys / Q000737:chemistry; D003343:Corrosion; D003722:Dental Alloys / Q000737:chemistry*; D003775:Dental Polishing / Q000379:methods; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D010984:Platinum / Q000737:chemistry; D011048:Polarography; D012464:Saliva, Artificial / Q000737:chemistry*; D017655:Silicon Compounds / Q000737:chemistry; D013499:Surface Properties; D014508:Urea / Q000008:administration & dosage / Q000737:chemistry*
chemical_list: D017554:Carbon Compounds, Inorganic; D002858:Chromium Alloys; D003722:Dental Alloys; D006047:Gold Alloys; D012464:Saliva, Artificial; D017655:Silicon Compounds; D010984:Platinum; D014508:Urea; C022088:silicon carbide