title: Corrosive and cytotoxic properties of compact specimens and microparticles of Ni-Cr dental alloy.
abstract: OBJECTIVE
  Nickel-chromium (Ni-Cr) dental alloys have been widely used in prosthodontic practice, but there is a permanent concern about their biocompatibility due to the release of metal ions. This is especially important when Ni-Cr metal microparticles are incorporated into gingival tissue during prosthodontic procedures. Therefore, the aim of this study was to examine and compare the corrosion and cytotoxic properties of compact specimens and microparticles of Ni-Cr dental alloy.
  
  
  METHODS
  Ni-Cr alloy, Remanium CSe bars (4 mm diameter), were made by the standard casting method and then cut into 0.5-mm-thick disks. Metal particles were obtained by scraping the bars using a diamond instrument for crown preparation. The microstructure was observed by an optical microscope. Quantitative determination and morphological and dimensional characterization of metal particles were carried out by a scanning electron microscope and Leica Application Suite software for image analysis. Corrosion was studied by conditioning the alloy specimens in the RPMI 1640 medium, containing 10% fetal calf serum in an incubator with 5% CO2 for 72 hours at 37°C. Inductively coupled plasma-optical emission spectrometry was used to assess metal ion release. The cytotoxity of conditioning medium (CM) was investigated on L929 cells using an MTT test. One-way ANOVA was used for statistical analysis.
  
  
  RESULTS
  After casting, the microstructure of the Remanium CSe compact specimen composed of Ni, Cr, Mo, Si, Fe, Al, and Co had a typical dendritic structure. Alloy microparticles had an irregular shape with a wide size range: from less than 1 μm to more than 100 μm. The release of metal ions, especially Ni and Mo from microparticles, was significantly higher, compared to the compact alloy specimen. The CM prepared from compact alloy was not cytotoxic at any tested dilutions, whereas CM from alloy microparticles showed dose-dependent cytotoxicity (90% CM and 45% CM versus control; p < 0.005).
  
  
  CONCLUSIONS
  Ni-Cr microparticles showed less corrosion resistance and lower biocompatibility than compact alloy. This could affect health on long-term exposure, especially in sensitized individuals.
authors.affiliation: Dental Clinic, Military Medical Academy, Belgrade, Serbia.
authors.forename: Ljubisa
authors.initials: L
authors.lastname: Ristic
authors.forename: Dragana
authors.initials: D
authors.lastname: Vucevic
authors.forename: Ljubica
authors.initials: L
authors.lastname: Radovic
authors.forename: Snezana
authors.initials: S
authors.lastname: Djordjevic
authors.forename: Milutin
authors.initials: M
authors.lastname: Nikacevic
authors.forename: Miodrag
authors.initials: M
authors.lastname: Colic
mesh_terms: D000535:Aluminum / Q000737:chemistry / Q000633:toxicity; D000818:Animals; D002460:Cell Line; D048430:Cell Shape / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002857:Chromium / Q000737:chemistry / Q000633:toxicity; D002858:Chromium Alloys / Q000737:chemistry / Q000633:toxicity*; D003035:Cobalt / Q000737:chemistry / Q000633:toxicity; D003343:Corrosion; D003734:Dental Casting Investment / Q000737:chemistry / Q000633:toxicity; D018130:Diamond / Q000737:chemistry; D005347:Fibroblasts / Q000187:drug effects; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007501:Iron / Q000737:chemistry / Q000633:toxicity; D008422:Materials Testing; D051379:Mice; D008855:Microscopy, Electron, Scanning; D008982:Molybdenum / Q000737:chemistry / Q000633:toxicity; D009532:Nickel / Q000737:chemistry / Q000633:toxicity; D010316:Particle Size; D012825:Silicon / Q000737:chemistry / Q000633:toxicity; D013054:Spectrophotometry, Atomic; D013499:Surface Properties
chemical_list: D002858:Chromium Alloys; D003734:Dental Casting Investment; D002857:Chromium; D003035:Cobalt; D018130:Diamond; D009532:Nickel; D008982:Molybdenum; D000535:Aluminum; D007501:Iron; D012825:Silicon
keywords: Ni-Cr; alloy; corrosion; cytotoxicity; microparticles