Which characteristic of amalgam is improved by the presence of zinc?

The presence of zinc in amalgam significantly enhances its corrosion resistance. Zinc acts as a scavenger, which can help to minimize the production of corrosion by-products that typically occur when mercury reacts with the amalgam components. This improved corrosion resistance is particularly important because it contributes to the longevity and durability of the restoration in a moist oral environment.

Corrosion is a critical factor that can lead to failure of dental materials, as it can cause the degradation of the material structure and the release of harmful by-products. Thus, amalgam with zinc provides an added layer of protection and stability, making it suitable for a wider range of clinical applications, particularly in areas prone to moisture and oral fluids.

In contrast, the other characteristics such as strength, setting time, and thermal conductivity are affected by different factors related to the composition and handling of the amalgam rather than the inclusion of zinc.