Why does high copper amalgam last longer than low copper amalgam?

High copper amalgam lasts longer than low copper amalgam primarily due to its increased corrosion resistance. In dental applications, corrosion can lead to the degradation of the material and compromise the integrity of the dental restoration. High copper amalgams contain additional copper, which significantly reduces the formation of corrosion products that can occur in low copper amalgams. This is because the copper in high copper amalgam interacts with the silver and tin present, leading to the formation of stable phases that are less susceptible to corrosion.

In contrast, low copper amalgams often have higher levels of tin, which can react more aggressively with moisture and other elements in the oral environment, leading to higher rates of corrosion and wear. Thus, the improved corrosion resistance in high copper amalgam leads to longer-lasting restorations that maintain their structural integrity over time.