Modifications of Glass Ionomer Cements Using Nanotechnology: Recent Advances

Glass ionomer cements (GICs) are dental materials that were invented by Wilson & Kent in 1972. They can chemically bond to enamel and dentin and can exhibit anti-cariogenic activity that allows the release and uptake of fluoride ions. They also possess the ability to render color. The setting reaction of GICs is a neutralization reaction that results in the formation of polycarboxylate salts. The most important GIC modification process involves the addition of resin components, resulting in the development of resin-modified glass ionomer cements (RMGICs), which contain self-and photo-curing systems. Modification of conventional GICs and RMGICs can be achieved by the incorporation of nano-sized fillers into the materials. This helps reduce the size of RMGICs. Conventional GICs and RMGICs can also be modified by introducing nano-sized bioceramics to the glass powder. It has been previously reported that the incorporation of nano-sized particles helps improve the mechanical properties of conventional GICs. Conversely, the commercially available nano-filled RMGICs do not hold any significant advantage over conventional RMGICs as far as the mechanical and adhesive properties are concerned. Glass carbomer is a novel glass ionomer material, and the bioactivity of which is better than the bioactivity of the conventional GICs. However, it is more brittle and less strong than the modern conventional GICs. Additionally, clinical techniques that can be used to transfer external energy on the surface of a GIC have also been used for modification. These techniques can be used to reduce the duration of the initial setting stage and improve the rate of the setting reactions, resulting in faster development of the mechanical properties. Premature failure of the restorations can be avoided under these conditions. The lack of long-term clinical studies limits the use of nano-modified glass ionomers and glass carbomers in daily clinical practice. More randomized clinical trials are required to justify the use of these modern modified materials.