What are Giomers

Giomers are a relatively new type of restorative material. The name "giomer" is a hybrid of the words "glass ionomer" and "composite", which pretty well describes what a giomer is claimed to be. Although glass-ionomer restorative materials such as Ketac-Fil (3M ESPE) and Fuji Type II (GC America) have some very important properties, such as fluoride release, fluoride rechargeability, and chemical bonding to tooth structure, they also have well-known shortcomings. Their esthetics, for example, are less than ideal and make them a poor second choice to resin composites for restoring esthetically-demanding areas. Also, they are sensitive to moisture contamination and desiccation, which can present the clinician with challenges during their placement. In the 1990s manufacturers improved these shortcomings by adding resins to glass ionomers to produce resin-modified glass ionomers. These products (e.g., Fuji II LC, GC America; Vitremer, 3M ESPE; Photac-Fil Quick, 3M ESPE) have much better esthetics and handling characteristics than glass ionomers. Importantly, they also retain many of the glass ionomer's beneficial properties, such as long-term fluoride release and the ability to be recharged with topically-applied fluoride. They tend, however, to discolor over time. In another attempt to "better" the glass ionomer restorative materials, compomers were also developed. They were touted as being similar to glass ionomers but having much better esthetics and being easier to place and polish. Unfortunately, some of the manufacturer's claims were not confirmed by published research. Although they handled better than GICs, they released much less fluoride and could not be recharged.

In the continuing quest for improved glass ionomer-like restoratives, manufacturers have developed and introduced a new class of materials called "giomers." As noted earlier, the term implies they are combinations of glass ionomers and composites. Their manufacturers claim they have properties of both glass ionomers (fluoride release, fluoride recharge) and resin composites (excellent esthetics, easy polishability, biocompatibility). Giomers are distinguished by the fact that, while they are resin-based, they contain pre-reacted glass-ionomer (PRG) particles. The particles are made of fluorosilicate glass that has been reacted with polyacrylic acid prior to being incorporated into the resin. The pre-reaction can involve only the surface of the glass particles (called surface pre-reacted glass ionomer or S-PRG) or almost the entire particle (termed fully pre-reacted glass ionomer or F-PRG). Giomers are similar to compomers and resin composites in being light activated and requiring the use of a bonding agent to adhere to tooth structure. Only one giomer is commercially available at the time of this writing, Shofu's Beautiful, (see at right) which uses the S-PRG technology. According to Shofu, Beautiful is indicated for restoring Class I through V lesions as well as for treating cervical erosion lesions and root caries. It is available in 13 shades and is supplied in syringes.

Little published research is available on the properties or performance of giomers. One recently published study compared the fluoride release of a glass ionomer, a resin-modified glass ionomer, a giomer, and a compomer. It found that while the giomer released fluoride, it did not have an initial "burst" type of release like glass ionomers, and its long-term (i.e., 28-day) release was lower than that of the other materials.¹ Another study found that a giomer, after polishing with Sof-Lex disks, had a smoother surface than a glass ionomer, and one that was comparable to that of a compomer and a resin composite.² A three-year clinical study comparing the performance of a giomer with that of a microfill resin composite in Class V erosion/abrasion/abfraction lesions has also been done. After measuring eight performance characteristics, no significant differences between the two materials were found.³

Almost assuredly, many other giomer products will become available in the future.