A comprehensive review of recent work on hydroxyapatite and glass ionomer cement: properties, limitations and synergistic dental applications

The regeneration and regrowth of hard tissue are challenges in the biomedical field of the 21st century. Even though there are several synthetic implants, researchers sought effective bioactive and biocompatible implants, which do not form any cross-reactions after implantation. For a few decades, hydroxyapatite (HAp) gained more attention in synthesizing implantable materials. Although polymer-doped hydroxyapatite, some metals, including titanium and platinum-doped hydroxyapatite were prepared to enhance the mechanical properties of nanohydroxyapatite (nHAp). Besides, Glass ionomer cement is essential for dental restorations because of its strong attachment to the tooth's enamel and fluoride release, which inhibits decay. Presently, the researchers are focused on preparing the complex of metal-doped nHAp with GIC (glass ionomer cement). The integration of GIC with HAp promotes biocompatibility, mechanical strength, durability, remineralization, and sustained fluoride release for better dental health. The combination improves bonding to tooth structure. This review provides insight into the special features of hydroxyapatite, metal-doped hydroxyapatite, and the complex of metal-doped HAp, essential features of good implants, and challenges of using pure HAp as bioimplants. The composition of GIC, various nanostructures added to enhance its properties, and the bioactivity mechanism of GIC are reviewed. Also, the review emphasizes the incorporation of above said materials into the GIC, and suitable mechanisms are discussed. The factors modulating GIC attributes after implantation are discussed. It also aids in selecting better quality material for making dental restoration.