A Method to Monitor Corrosion of Chromium-iron Alloys by Monitoring the Chromium Ion Concentration in Urine

Abstract

Binary alloys of chromium-iron (Cr-Fe) are no longer used in dental and orthopaedic applications, and were used only for comparative purposes in the present study. Four kinds of Cr-Fe binary alloys, namely, 10 mass%, 15 mass%, 20 mass% and 30 mass%Cr in Fe, and 100%Cr and SUS316L were prepared. These metals were subcutaneously implanted into rats for four months. There was no significant difference in body weights and organ weights among control (sham-operation) and implant-groups, and no significant accumulation of Cr and Fe in the blood, liver or kidney of the alloy implant groups. To clarify the usefulness of urinary monitoring, the Cr and Fe concentrations in rat urine after implantation were analyzed. Alloy implant groups, including the SUS316L group, intended to excrete higher urinary Cr amounts than the control group during the 3 weeks after implantation. Urinary Cr and Fe amounts of the 15%Cr-alloy group showed especially high values in comparison not only with the control level but also the other alloy groups. The visual corrosion extents of the retrieved implants showed the following order: 10%Cr > 15%Cr > 20%Cr > 30%Cr > 100%Cr, SUS316L, and did not always correlate with the levels of the urinary amounts of Cr and Fe. From these findings, monitoring of urinary metal amounts is considered to be useful to monitor the in vivo elution property non-invasively.

Tissue Reactions and Sensitivity to Iron-Chromium Alloys

“…25) Hamanaka and Tsuchiya et al studied in vivo release of metallic ions from each material when implanted into animals, and measured Cr and Fe contents in the urine at regular time interval. 5,6) In early stage until 14-21 day after implantation, the urine Cr content from the animals implanted 15%-20%Cr-Fe alloy was higher than those implanted a 30%Cr-Fe alloy, 100%Cr or SUS316L. For Fe concentration in urine, similar tendency of release was observed.…”

“…The rust deposition on the surface of each metal sample after implantation was correlated with in vitro Cr and Fe elution pattern from the alloy and the urine Cr and Fe concentrations in early stage. 5,6,25) These suggest that the release of Cr and Fe ions occurred in the body as the results of corrosion during implantation in the case of 10-20%Cr-Fe alloys.…”

“…The elevated level of metal ion was found in blood, urine and tissue of the patients and animals those received metal implants. [3][4][5][6] The corrosion products and highly concentration of metallic ion, for example nickel (Ni), may cause inflammatory reaction surrounding the implanted alloys. [7][8][9][10] The components of these alloys, such as Cr, Co and Ni, are known to be contact allergens.…”

Improved Biocompatibility of Titanium–Zirconium (Ti–Zr) Alloy: Tissue Reaction and Sensitization to Ti–Zr Alloy Compared with Pure Ti and Zr in Rat Implantation Study

“…We previously observed that animals became sensitized by the high amount of Cr ion released from the easily corrosive CrFe alloy implanted in them. 5,26) The stable oxide complex layer that formed on the surfaces of Ti, Zr, and their alloys allowed little release of their ions. 16,18,25) Although highly unusual, cases of contact sensitivity to pacemakers which are made of Ti have been reported.…”

“…2,3) Elevated levels of metal ions have been found in blood, urine, and tissues of patients and animals that have received metal implants. [2][3][4][5][6] Metallic ions, such as nickel (Ni), Co, and Cr, are known to cause adverse tissue reactions and allergy. [7][8][9][10][11][12][13] Titanium (Ti) and its alloys are currently considered the most attractive metallic materials for orthopedic and dental surgery.…”