Under standard conditions, ammonium can form a metallic amalgam with mercury. Restorative materials include dental amalgam, composite resin, porcelain, and gold. This is typically the case in amalgam restorations and endodontic treatment. This contributes to a daily mercury exposure for those with amalgam filling. Corrosion may significantly affect the structure and mechanical properties of set dental amalgam. The gold is produced by boiling away the mercury from the amalgam. The placement of amalgam restorations can potentially cause sensitivity post-operatively. Silver is also a component in dental amalgam. The corrosion however is still much lower than conventional amalgam. This effect is reduced by incorporating copper into amalgam alloys. This was the beginning of what is known as the first dental amalgam war. There are circumstances in which composite serves better than amalgam. One popular route entails reduction of benzoin using zinc amalgam. These particular individuals may experience adverse effects caused by amalgam restoration. The process occurs via the formation of an amalgam of the aluminium.