# Electrochemical Interactions of Titanium and Cobalt–Chromium–Molybdenum Alloy in Different Solutions

## TL;DR

This study examines how titanium and a titanium-magnesium composite interact electrochemically with a cobalt-chromium-molybdenum alloy in common oral solutions, revealing significant differences in corrosion stability.

## Contribution

The study introduces a novel Ti–magnesium composite and evaluates its electrochemical behavior with CoCrMo in various oral solutions, revealing greater susceptibility compared to pure titanium.

## Key findings

- Galvanic potential differences of ~983 mV were observed for BIACOM TiMg-CoCrMo in Coca-Cola.
- CP4 Ti-CoCrMo couples showed 830 mV in Coca-Cola, indicating electrochemical instability.
- Both materials showed significant potential increases in Elmex fluoride gel.

## Abstract

Pure titanium (Ti) and its alloys are the gold standard for dental implants because a stable titanium dioxide passive film provides excellent corrosion resistance in physiological environments. In this study, we aimed to examine electrochemical interactions between Ti and cobalt–chromium–molybdenum alloy (CoCrMo), and between a novel Ti–magnesium composite (BIACOM TiMg) and CoCrMo, when immersed in everyday solutions representing beverage or oral hygiene exposure. Test solutions included Coca-Cola®, lemon juice, Elmex® fluoride gel, Listerine® Cool Mint, and Sensodyne® fluoride paste. Immersion experiments paired Ti sticks with CoCrMo sticks and, separately, BIACOM TiMg with CoCrMo sticks, with three measurements per configuration. When galvanically coupled with CoCrMo, immersion in Coca-Cola produced galvanic potential differences of ~983 mV for the BIACOM TiMg-CoCrMo couple and 830 mV for the commercially pure grade 4 (CP4) Ti-CoCrMo couple, indicating significant electrochemical instability. Both materials showed significant potential increases in Elmex fluoride gel. Listerine Cool Mint and Sensodyne fluoride exposure produced electrochemical interactions exceeding 200 mV. Significant differences in corrosion stability were observed between CP4 Ti and BIACOM TiMg. These findings indicate that material pairing and electrolyte environment significantly influence galvanic behavior, with the Ti-Mg composite showing greater susceptibility than CP4 Ti, informing dental/biomedical material selection in oral environments.