Ion release from Ni-Cr-Mo and Co-Cr-Mo casting alloys

Area of Science:

• Biomaterials Science
• Corrosion Engineering
• Materials Science

Background:

• Nickel-chromium-molybdenum (Ni-Cr-Mo) and cobalt-chromium-molybdenum (Co-Cr-Mo) alloys are widely used in dental and medical implants.
• Understanding their corrosion behavior in physiological environments is crucial for long-term device performance and patient safety.

Purpose of the Study:

• To quantitatively assess and compare the substance loss (corrosion) of commercially available Ni-Cr-Mo and Co-Cr-Mo alloys.
• To determine the range and variability of corrosion rates for these alloy types under specific laboratory conditions.

Main Methods:

• Four commercial Ni-Cr-Mo and four Co-Cr-Mo alloy samples were exposed to a corrosive solution (0.1 mol/L lactic acid and 0.1 mol/L sodium chloride).
• Substance loss was measured over a 5-week period.
• Dissolved ions were quantified using atomic absorption spectroscopy.

Main Results:

• Ni-Cr-Mo alloys displayed a broad spectrum of corrosion rates, with average values after 35 days ranging from 0.54 to 3,261 µg/cm².
• Co-Cr-Mo alloys showed a narrower distribution of corrosion rates, ranging from 0.43 to 34.9 µg/cm².
• Significant variability in corrosion resistance was observed within the Ni-Cr-Mo alloy group.

Conclusions:

• Co-Cr-Mo alloys generally demonstrate more predictable and lower corrosion rates compared to Ni-Cr-Mo alloys in this simulated oral environment.
• The wide variation in Ni-Cr-Mo alloy performance highlights the importance of alloy selection for demanding biomedical applications.
• Further research into factors influencing Ni-Cr-Mo alloy corrosion is warranted.