What is the effect of longer trituration time on amalgam expansion?

Longer trituration time generally results in a decrease in the expansion of amalgam. Trituration is the process of mixing dental amalgam alloys with mercury to create a workable mass. During this mixing process, achieving the right balance of time is crucial; too short a trituration can lead to incomplete mixing and a product that may retain more moisture or dissimilar particle sizes, which can promote more expansion.

On the other hand, longer trituration times tend to lead to a more homogenous mixture. This thorough mixing can reduce the tendency for the amalgam to expand excessively because adequate incorporation of the alloy particles with mercury ensures better inter-particle bonding. Furthermore, excessive trituration can actually break down the alloy particles and reduce the formation of proper crystalline structures, which can also influence expansion properties negatively.

In essence, the correct choice indicates that with increased trituration time, the control over the physical properties of the amalgam improves, thus leading to decreased expansion during the setting process.