text: Dental sealants were first introduced as part of the preventative programme, in the late 1960s, in response to increasing cases of pits and fissures on occlusal surfaces due to caries. This led to glass ionomer cements to be introduced in 1972 by Wilson and Kent as derivative of the silicate cements and the polycarboxylate cements. The glass ionomer cements incorporated the fluoride releasing properties of the silicate cements with the adhesive qualities of polycarboxylate cements. This incorporation allowed the material to be stronger, less soluble and more translucent (and therefore more aesthetic) than its predecessors.
  Glass ionomer cements were initially intended to be used for the aesthetic restoration of anterior teeth and were recommended for restoring Class III and Class V cavity preparations. There have now been further developments in the material's composition to improve properties. For example, the addition of metal or resin particles into the sealant is favoured due to the longer working time and the material being less sensitive to moisture during setting.
  When glass ionomer cements were first used, they were mainly used for the restoration of abrasion/erosion lesions and as a luting agent for crown and bridge reconstructions. However, this has now been extended to occlusal restorations in deciduous dentition, restoration of proximal lesions and cavity bases and liners. This is made possible by the ever-increasing new formulations of glass ionomer cements.
  One of the early commercially successful GICs, employing G338 glass and developed by Wilson and Kent, served purpose as non-load bearing restorative materials. However, this glass resulted in a cement too brittle for use in load-bearing applications such as in molar teeth. The properties of G338 being shown to be related to its phase-composition, specifically the interplay between its three amorphous phases Ca/Na-Al-Si-O, Ca-Al-F and Ca-P-O-F, as characterised by mechanical testing, differential scanning calorimetry (DSC) and X-ray diffraction (XRD), as well as quantum chemical modelling and ab initio molecular dynamics simulations.