Zirconomer and Zirconomer Improved ( White Amalgams ) : Restorative Materials for the Future . Review

Dental caries has been considered as a historically important component of the global oral disease burden. Thus, the quest for an ideal restorative material with optimum physical properties and durability exists. There was a lack of availability and development in the field of restorative materials. Though amalgam has many drawbacks, such as postoperative tooth sensitivity, susceptibility to fracture of the restored teeth, microleakage, mercury environmental pollution, and high incidence of development of secondary caries, it has been used for more than a century as a successful restorative material. Many tooth-colored materials have evolved to replace amalgam in the recent past. The popularity of resin based composite restoration has increased because of its excellent esthetic and other favorable characteristics. However, failure is also seen in composite restoration in posterior dentition as excessive wear, polymerization shrinkage, open inter proximal contacts, tooth sensitivity, secondary caries, irreversible pulpitis, and restoration fracture. The unique properties of glass ionomer cement (GIC), such as adhesion to moist teeth, anti-carcinogenic character, lack of exothermic polymerization, excellent adhesion to dentin, close thermal expansion to tooth, satisfactory biocompatibility, make it an important material in dental applications. One of the major drawbacks is its weak mechanical properties like brittleness, low strength, and toughness. Hence GICs were mostly used for the restoration of anterior teeth and in areas without any load due to their poor mechanical strength. Several modifications have been introduced with the purpose of enhancing their mechanical properties. The introduction of resin-modified GICs with superior mechanical strength was used in the posterior restorations. Several strategies are followed to enhance the mechanical properties, such as addition of zirconia, hydroxyapatite, N-vinyl pyrrolidone, fluoroapatite, and HA/ZrO2 is a well-known method to enhance the mechanical properties of GIC. New GIC formulations called as Zirconomer® and zirconomer improved® (white amalgams) are novel materials, composed of ceramic and zirconia reinforced glass ionomer cements that could overcome the drawbacks of previously used amalgam as well as other tooth-colored restorative materials. They exhibit the strength of amalgam and at the same time maintain the fluoride releasing capacity of GICs. The aim of the current review was to present the new zirconomer family regarding their composition, properties, mechanism of zirconia toughening, previous researches about them. This is to ensure the right choice of the material for clinical purposes.