[Change of ion precipitation and surface roughness of three dental alloys coexisting]

To study the change of ion precipitation and surface roughness of three dental alloys'coexisting in standard electrolyte solution, in order to provide a reference for the selection of clinical alloy materials.

Standard samples of Ni-Cr alloy, Co-Cr alloy and Au-Ag-Pd alloy were prepared and divided into 5 groups: Ni-Cr alloy(group N), Co-Cr alloy(group C), Au-Ag-Pd alloy(Group A), Ni-Cr alloy contact with Au-Ag-Pd alloy(group NA), Ni-Cr alloy contact with Co-Cr alloy(group NC). All groups of alloys were soaked in standard electrolyte solution (T=37 ℃, pH=2.31) for 7 days. Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the amount of ions released from each group. The surface morphology of each group was observed and the surface roughness(Ra) was measured using atomic force microscope（AFM）. SPSS 18.0 software package was used for statistical analysis.

The amount of nickel ions released from group N, NA, NC was (1.32±0.03) μg/cm², (2.13±0.07) μg/cm², (1.53±0.08) μg/cm², respectively. Nickel ions of group NA and NC was significantly more than that of group N(P<0.05), nickel ions of group NA was significantly more than that of group NC(P<0.05). The amount of chromium ions released from group N, NA, NC was (0.06±0.01) μg/cm², (0.08±0.01) μg/cm², (0.05±0.01) μg/cm², respectively, the amount of chromium ions of group NA was significantly more than that of group NC(P<0.05). The surface roughness of Ni-Cr alloy in group N, NA, NC was (4.60±0.16) nm, (5.37±0.08) nm, (5.04±0.15) nm, respectively. The surface roughness of Ni-Cr alloy in group NA and group NC was significantly larger than that in group N (P<0.05). When contact with Au-Ag-Pd alloy or Co-Cr alloy, the amount of nickel ions released and the surface roughness of Ni-Cr alloy both significantly increased. Compared with Co-Cr alloy, Au-Ag-Pd alloy caused Ni-Cr alloy to release more nickel, chromium ions and formed a rougher surface.