What is the result of exposing amalgam to moisture during placement?

Exposing amalgam to moisture during its placement can lead to excessive expansion. This occurs because moisture can cause the amalgam to undergo a reaction that affects its dimensional stability. The presence of water can interfere with the setting process of the amalgam, leading to an increase in the volume of the material.

When amalgam is mixed with moisture, the zinc in the material can react with water to produce hydrogen gas, which may lead to a cloudiness in the material and create voids or expand the amalgam more than usual. This excessive expansion can result in complications such as pressure against the tooth structure, which may ultimately compromise the integrity of the restoration, leading to postoperative sensitivity or failure of the amalgam restoration.

In contrast, minimal expansion or excessive contraction would not adequately describe the effects of moisture exposure. Improved strength is unlikely when amalgam is compromised by moisture during placement, as this could weaken the bond between the amalgam and the tooth structure, leading to a less effective restoration overall.