American Board of Orthodontics (ABO) Practice Exam

The inclusion of chromium in wire composition significantly enhances corrosion resistance. Chromium is known for its ability to form a passive oxide layer on the surface of stainless steel, which protects the underlying metal from various forms of corrosion, including pitting and stress corrosion cracking. This quality is particularly valuable in orthodontic applications where wires are exposed to the moist environment of the mouth and must endure exposure to different pH levels and potentially corrosive substances found in food and beverages.

While other materials and compositions might influence tensile strength, thermal conductivity, or elasticity, the primary and most impactful property enhanced by chromium is its resistance to corrosion. This durability ensures that orthodontic wires maintain their performance and longevity under the demanding conditions of oral environments, making them safer and more effective for patient use over time. Thus, the presence of chromium serves a crucial role in extending the service life of orthodontic appliances.