What can excessive expansion of an amalgam restoration be caused by?

Excessive expansion of an amalgam restoration is primarily caused by over trituration. When amalgam is over triturated, it becomes more plastic and can be packed too tightly into a cavity, leading to an increase in mercury content, which in turn can cause expansion. This is a crucial factor because over triturated amalgam may not only expand excessively, but it can also affect the consistency and handling of the material, leading to compromised restoration integrity.

Moisture contamination does indeed affect the performance of dental materials, but it is more commonly associated with issues such as a reduction in bond strength or compromised setting efficiency rather than direct expansion. While oxidation can impact the surface of amalgam, it doesn’t directly influence the expansion. Over condensation refers to the improper compaction of amalgam, which might lead to high density but does not usually result in excessive expansion. Therefore, focusing on the effects of over trituration emphasizes the importance of proper mixing techniques in maintaining the stability and longevity of amalgam restorations.