Glass ionomer cements are fluoride-releasing materials that chemically bond to tooth structure, used for direct restorations, cavity liners and bases, luting crowns and orthodontic bands, and pit-and-fissure sealing. Their self-adhesive nature and moisture tolerance make them useful in pediatric dentistry, high-caries-risk patients, and situations where isolation is difficult, while resin-modified variants add improved strength and esthetics. Continuous fluoride release provides an anti-cariogenic benefit that distinguishes glass ionomers from other restorative and luting materials, making this category a mainstay in preventive and minimally invasive restorative dentistry.