title: [Effect of investment for titanium crown and bridge on reactive layer of castings].
abstract: OBJECTIVE
  To investigate the effect of self-developing investment (FUS-invest) on the reactive layer of titanium castings.
  
  
  METHODS
  Three 10 mm x 10 mm x 1 mm pure titanium castings were founded using FUS-invest. Metallographical structure of reactive layer was observed. X-ray diffraction (XRD) and scanning electron microscope with energy-dispersive spectrum (EDS) were used to analyze the status of composition of the casting surface. Micro-Vickers hardness was measured.
  
  
  RESULTS
  The metallograph indicated that the reactive layer was composed of coarse flake-shaped alpha phase of grains. The value of micro-Vickers hardness with the range 243 to 314 MPa had not significantly difference under the depth of 105 microm beneath the surface. The XRD pattern clearly showed the peaks of ZrO2, SiO2, Mg2TiO4 and TiO2. EDS analysis demonstrated that the main elements were Al, Si, Zr and Cl.
  
  
  CONCLUSIONS
  FUS-invest is suited for pure titanium casting because of the thin reactive layer and less change to metallographical structure.
authors.affiliation: Dept. of Stomatology, The Chinese PLA General Hospital, Beijing 100853, China.
authors.forename: Se-Fei
authors.initials: SF
authors.lastname: Yang
authors.forename: You-Xu
authors.initials: YX
authors.lastname: Wang
authors.forename: Tian-Wen
authors.initials: TW
authors.lastname: Guo
authors.forename: Hong-Chen
authors.initials: HC
authors.lastname: Liu
mesh_terms: D003442:Crowns; D003734:Dental Casting Investment; D003735:Dental Casting Technique; D006244:Hardness; D006801:Humans; D007449:Investments; D012822:Silicon Dioxide; D013499:Surface Properties; D014025:Titanium
chemical_list: D003734:Dental Casting Investment; D012822:Silicon Dioxide; D014025:Titanium