Advantages And Disadvantages Of Glass Ionomer Cements

After amalgam, glass ionomer cements are the most widely used restorative materials for fillings and as luting agents in dentistry. This is because they have several major advantages over other filling materials.

Glass ionomer cements are based on polyacrylic acid and filler particles such as quartz. The setting reaction involves the acid attacking the filler particles releasing ions and the formation of a gel -like matrix.

Glass ionomer cements can be mixed by adding water to freeze dried powder or it can be presented as a light cured material which is mixed in a machine. In addition, glass ionomers are available which are dual cured. Finally, glass ionomer cements are available which include metallic particles for extra-strength and also resin modified cements adding composites are available to increase aesthetics.

Here Are The Main Advantages Of Glass Ionomer Cements

1. Out of amalgam, composite and glass ionomer cement, only glass ionomer cement has the inherent ability to bond onto enamel and dentine. The mechanism of the bond is both chemical and micro-mechanical.
2. Glass ionomer cements also release fluoride when it has fully set. This is especially useful in deep cavities where remaining caries can be halted by promoting fluoride release into the dentine plus the adhesion with enamel and dentine makes sure that carries can remain inactive.
3. Although glass ionomer cannot be used in posterior cavities, it is extremely useful as an intermediate filling material such as cases where you want to stabilise a carious dentition such as in rampant caries.

Glass ionomer is also available as a silver reinforced material which is able to withstand occlusal forces better so will have increased longevity. In this regard, it is useful for deciduous teeth which have a limited lifespan in the mouth.

1. The aesthetics of the early glass ionomer cements were not particularly good enough for them to be used as anterior filling materials but at least they were tooth coloured to some extent.

However, over time, the glass ionomer cement range has improved considerably and one of the earliest improvements was from Fuji which has a wide range of glass ionomer cements today.

The aesthetics have much improved as a consequence. Furthermore, aesthetics have come closer to composite due to the advent of composite resin modified glass ionomer cements, RMGIC.

1. The above advantages of glass ionomer are evident in certain circumstances such as a core build-up material under a crown preparation and to provide a good seal for the access cavity following root canal treatment.

They have major advantages as a luting cement for crowns and inlays. This is due to their ability for chemical and micromechanical bonding. This is because of their strength and their biological abilities. Finally, glass ionomer cement is an excellent biomimetic material to replace lost dentine in deep cavities.

1. A major advantage of glass ionomer over composite is that glass ionomer cements are not overly technique sensitive. Composites are extremely technique sensitive and many pitfalls are there for the unwary practitioner. Even moisture from a patient’s breathing will cause contamination of the cavity as a dry field is essential.

Glass ionomer however can be used in situations where composite would be impossible such as buccal class V cavities where there is little enamel and presence of some moisture with residual caries.

This area will have gingival crevicular fluid and gingival bleeding. If the caries is slightly sub-gingival, composite will be impossible to use. Glass ionomers are absolutely ideal in these situations and they have a good long-term track record.

Here Are The Main Disadvantages Of Glass Ionomer Cement

1. They do not have adequate wear resistance for use in posterior occlusal loading situations. Having said that, they are perfectly fine to use as a temporary or an intermediate filling material.
2. As above, they do not have the strength to use in posterior occlusal loading situations however are good to use as a temporary or an intermediate filling material.
3. The aesthetics of glass ionomer cement are not as good as composites which are far superior but the gap is narrowing all the time. Fuji is the main company that has driven the advent of glass ionomer cements.
4. Glass ionomer cement restorations can sometimes be difficult to discern in radiographs as they are less radio-opaque than amalgam and composite. Their radiolucency is similar to dentine which makes it difficult to pick up secondary caries on the radiograph.