 Glass ionomer cements are a type of dental material that's set through an acid-base reaction within two to three minutes and form hard, reasonably strong materials with acceptable appearance. They release fluoride and are bioactive, forming a strong interfacial ion exchange layer at the interface with the tooth responsible for their adhesion. Modified forms of glass ionomers, such as resin-modified glass ionomers and glass carbamer, have good physical properties but may compromise biocompatibility due to the presence of resin components. Glass carbamer has slightly inferior properties compared to modern conventional glass ionomers and more information is needed to determine their bioactivity. This article was authored by Sharon Burkay-Sidoux and John W. Nicholson.