Galvanic interaction between titanium and gallium alloy or dental amalgam

Area of Science:

• Materials Science
• Biomaterials Engineering
• Electrochemistry

Background:

• Titanium (Ti) is widely used in dental implants.
• Dental restorations often involve alloys placed in proximity to titanium.
• Understanding galvanic interactions is crucial for long-term material stability.

Purpose of the Study:

• To investigate the in vitro galvanic interaction between titanium and dental filling alloys.
• To assess the influence of varying area ratios on galvanic effects.
• To correlate observed interactions with alloy electrochemical properties.

Main Methods:

• Tested cast titanium, high-copper amalgam, and gallium-based alloys.
• Recorded polarization curves for individual alloys.
• Formed galvanic couples at Ti/filling alloy area ratios of 1:1, 2:1, 4:1, and 6:1.
• Measured galvanic currents and potentials in synthetic saliva at 37°C.

Main Results:

• Titanium initially anodic, then reversed polarity upon exposure.
• Galvanic potential and current density increased with higher Ti/alloy area ratios.
• Gallium alloy exhibited larger current increases and smaller potential increases compared to amalgam.
• Galvanic current densities were ~10⁻⁸ A/cm² for Ti/amalgam and 10⁻⁷ to 10⁻⁶ A/cm² for Ti/gallium alloy.

Conclusions:

• Galvanic interaction between titanium and direct filling alloys is generally small.
• High-copper dental amalgams are unlikely to suffer significant galvanic corrosion with titanium.
• Gallium-based alloys may face more detrimental galvanic effects due to their lower inherent corrosion resistance.