title: Effects of recasting on the biocompatibility of a Ni-Cr alloy.
abstract: OBJECTIVE
  To evaluate the effects of recasting on the biocompatibility of a commercially available Ni-Cr alloy.
  
  
  METHODS
  The alloy tested was cast and subsequently recast four more times. For each cast condition, 24 disk shaped specimens were fabricated (5 mm in diameter, 0.5 mm in thickness). All the recasting was performed without adding new alloy. After the first cast and following each recast, the surface composition and microstructure of the alloy were determined using an X-ray fluorescence spectrometer and optical microscope, respectively. The in vitro cytotoxicity and in vivo mucous irritation potential of the cast and recast Ni-Cr alloy were investigated. The results were statistically analysed at the significance level of 0.05.
  
  
  RESULTS
  Recasting neither yielded to cytotoxicity or to changes in the surface composition of the Ni-Cr alloy tested. However, an increase in impurities and porosity of the surface structure was observed with recasting. Also, the segregation of the impurities to grain boundaries was evident after multiple castings. After the fourth recast, the alloys showed significantly greater mucosal irritation than the control.
  
  
  CONCLUSIONS
  After fourth recast, the alloy of this type may contribute to mucosal inflammation. Furthermore, there is a need for diverse methods addressing different biological endpoints for the evaluation of dental alloys.
authors.affiliation: Department of Prosthodontics, Fujian Medical University, Fuzhou, People's Republic of China.
authors.forename: Chang Yuan
authors.initials: CY
authors.lastname: Zhang
authors.forename: Hui
authors.initials: H
authors.lastname: Cheng
authors.forename: Dong Hong
authors.initials: DH
authors.lastname: Lin
authors.forename: Ming
authors.initials: M
authors.lastname: Zheng
authors.forename: Mutlu
authors.initials: M
authors.lastname: Ozcan
authors.forename: Wei
authors.initials: W
authors.lastname: Zhao
authors.forename: Hao
authors.initials: H
authors.lastname: Yu
mesh_terms: D000535:Aluminum / Q000032:analysis; D000818:Animals; D001608:Beryllium / Q000032:analysis; D001672:Biocompatible Materials / Q000737:chemistry* / Q000633:toxicity; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002857:Chromium / Q000032:analysis; D002858:Chromium Alloys / Q000737:chemistry* / Q000633:toxicity; D006224:Cricetinae; D003735:Dental Casting Technique; D017743:Equipment Reuse; D005260:Female; D005347:Fibroblasts / Q000187:drug effects; D007509:Irritants / Q000633:toxicity; D008297:Male; D008422:Materials Testing; D008647:Mesocricetus; D051379:Mice; D008853:Microscopy; D008982:Molybdenum / Q000032:analysis; D009061:Mouth Mucosa / Q000187:drug effects; D009336:Necrosis; D009532:Nickel / Q000032:analysis; D016062:Porosity; D013052:Spectrometry, X-Ray Emission; D013280:Stomatitis / Q000139:chemically induced; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D002858:Chromium Alloys; D007509:Irritants; D002857:Chromium; D009532:Nickel; D008982:Molybdenum; D000535:Aluminum; D001608:Beryllium