Trace Element (TE) Release from Two Different Base Alloys Unde Conditions Imitating Oral Saliva

Electrochemical conditions in the oral cavity lead to a release of metal ions into the patient\u27s saliva. The aim of this study was to examine and compare the types andquantities of metal ions released from two base alloys: Co-Cr-Mo alloy (WironitR, Bego, Germany) and Ni-Cr alloy (Wiron 99, Bego, Germany) under in vitro conditions imitating artificial saliva. We soaked ten sets of each alloy having 497 mm2 exposure surface for 1, 2, 3, 4, 5, 6, 7, 14, 21 and 30 days (six pieces each set) in phosphate buffered saline (pH 6.0). TE in the phosphate buffered saline (saliva) were assessed by ICP-AES (JY 50P, Jobin-Ywon, France) with the detection limit of 10 mg/L. We found detectable amounts (mg/L) of TE (Mean SD) released from Co-Cr-Mo alloy (Mean SD): Co 337 (170), Fe 21 (15) Zn 87 (56), Ni 41 (68), and Cr 49 (42) and detectable amounts of TE released from Ni-Cr alloy (Mean SD): Co 265 (300), Fe 247 (256) Zn 92 (46), Ni 542 (668), and Cr 396 (410). The manufacturer did not indicate the presence of Fe, Zn, and Ni in the Co-Cr-Mo alloy and the presence of Fe, Co and Zn, in the Ni-Cr alloy. A significantly higher amount of Fe, Ni and Cr was released from Ni-Cr alloy (p<0.05), and a considerably higher amount of Co was released from Co-Cr-Mo alloy, although it did not reach a statistically significant level (p>0.05), while there was no significant difference between the two alloys for Fe ion release (p>0.05). We must keep in mind that the amount of the released TE may be much higher than the reported values in this study, after the laboratory procedures (casting, polishing, etc.) and allergenic essential TE Cr, Co, and Ni may be present locally in a considerably higher amount