Composite fillings (sometimes called composite-resin or white fillings) don't have these problems, because they're made from plastics mixed with ceramic particles. Although they look more natural than amalgam, they're harder to fit and don't last as long: while amalgam fillings might last 10–20 years, composite fillings last more like 5–10 years and then need replacing.
Cermet fillings combine the advantages of amalgams and composites. They're stronger than composites and as quick and easy to fit as amalgams (always a concern for nervous patients, especially young children), but contain no harmful mercury. Typical cermet fillings are made from a mixture of a ceramic composite and metal (silver) particles, so they're silver-colored, and look more like traditional amalgam fillings than white fillings. The ceramic composite, which is called glass ionomer, sounds complex but is simply a composite of glass particles (calcium-aluminium-fluoride-silicate) and a plastic polymer (polycarboxlate acid); it has the added benefit of releasing fluoride to help strengthen teeth. Cermet fillings have been less popular since the 1990s, following the development of another new type of filling called resin-modified glass ionomer (RMGI), which proved to be stronger, longer-lasting, and quicker to fit, and more closely matches the natural color of teeth.