Amalgam (dentistry) and other metals may be present in some alloys. This combination of solid particles is known as amalgam alloy. The composition of the alloy particles are controlled by the ISO Standard (ISO 1559) for dental amalgam alloy in order to control properties of set amalgam such as corrosion and setting expansion. It is important to differentiate between dental amalgam and the amalgam alloy that is commercially produced and marketed as small filings, spheroid particles, or a combination of these, suitable for mixing with liquid mercury to produce the dental amalgam. Amalgam is used most commonly for direct, permanent, posterior restorations
Amalgam (dentistry) or longer to reach a reasonably high value. At the time when the patient is dismissed from the surgery, typically some 15–20 minutes after placing the filling, the amalgam is relatively weak. Therefore, dentists need to instruct patients not to apply undue stress to their freshly placed amalgam fillings. In addition, amalgam restorations are brittle and susceptible to corrosion. The alloys are broadly classified as low-copper (5% or less copper) and high-copper alloys (13% to 30% copper). The solid particles of the alloy are either spherical or irregularly shaped microspheres of various sizes or a combination of the two. The