title: [The cytotoxicity of N48 NdFeB magnets coated with titanium-nitride].
abstract: OBJECTIVE
  To evaluate the effect of N48 NdFeB magnets coated with titanium-nitride on the growth and apoptosis of L929 mouse fibroblast cells, and to determine the material biocompatibility.
  
  
  METHODS
  The NdFeB magnets coated with titanium-nitride, bare NdFeB magnets and ordinary brackets were put into RPMI-1640 to prepare fusions. L929 mouse fibroblast cells were cultivated in the negative control liquid, positive control liquid, 100%, 50% and 25% sample fusions, respectively. The cell proliferation vitality was detected by MTT assay and the relative growth rate was calculated.Cell scatter diagrams of the negative control liquid, 100% titanium-nitride coated magnets fusion and bare magnets fusion were detected by flow cytometry Annexin V/PI double staining method. The ratios of normal cells, early apoptosis, advanced apoptosis and necrosis cells were calculated. The results were analyzed for paired t test using SPSS11.5 software package.
  
  
  RESULTS
  The toxic levels of N48 NdFeB coated with titanium-nitride were ranked as 0-1. The toxic levels of bare magnets were ranked as 2. The cell scatter diagrams showed that there was no significant difference in living cell, early apoptosis and necrosis between magnets coated with titanium-nitride and control group. But there was significant difference between the bare magnets group and control group.
  
  
  CONCLUSIONS
  The N48 NdFeB magnets coated with titanium-nitride have good biocompatibility.
authors.affiliation: Department of Orthodontics, School of Stomatology, China Medical University, Shengyang, Liaoning Province, China.
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Cao
authors.forename: Zhi-Ming
authors.initials: ZM
authors.lastname: Hou
authors.forename: Ming
authors.initials: M
authors.lastname: Chu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D005347:Fibroblasts; D059346:Magnets; D051379:Mice; D014025:Titanium
chemical_list: C041500:titanium nitride; D014025:Titanium