Medental Glass Ionomer cements (also called polyalkenoate cements) are a category of the cements group used by Dentists. They are made by diluted polyacrylic acid and fine glass powder without lead. Polyacrylics form with the glass a strong matrix chemically compatible with dental composite, metal, and dentine. They do not shrink, which is why these cements are successfully used as luting, liners or restorative depending on the thickness of the polyacrylic acid liquid in the mixture with the glass. Glass Ionomer is a “long term cement” of use from one week to four months but also, they can be used as definitive cements.