 Glass ionomers are a type of dental material used in restorative dentistry. They are composed of glass powder, phosphate glass, and acrylic monomer, and when mixed together, they form a hard, durable material. The material is biocompatible and releases fluoride, making it ideal for use as a filling material. Glass ionomers are known for their quick setting time, two to three minutes, and ability to bond to teeth. Additionally, they can be modified to increase strength and improve physical properties. This article was authored by Sharon Burkay-Sidoux and John W. Nicholson.