Casted titanium for dental applications: an XPS and SEM study

Casted titanium for dental crowns has been investigated by means of X-ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The samples were prepared according to the Ohara process. XRD analysis revealed that the investment consisted essentially of SiO2, Mg2P2O7, SiO2 x H2O and Mg2SiO4. SEM experiments combined with EDX analysis revealed the following atomic concentrations Si (62.6%), Mg (19.7%), P (17.1%), and Ca (0.6%). After casting, the titanium samples exhibit a rough and irregular surface, and XRD analysis indicated that titanium contains essentially the alpha phase and traces of the beta phase. After demoulding titanium samples, the investment side which was in contact with titanium was black colored, proving the reaction between titanium and the investment. XPS analysis performed on this side of the investment indicated that the Si 2p peak presents a shoulder on the low binding energy side and thus suggest that SiO2 has been transformed into metallic Si.