What are the advantages of Glass Ionomer Cement?
Glass ionomer cement, or GIC, as it’s often abbreviated to, is a dental restorative material that can be used as a filling material, sealant, liner or luting cement.
On the rise in popularity due to the growing demand for teeth coloured restorations, glass ionomers provide unique advantages over alternative restoratives, most notably the ability to release fluoride.
But like all restorative materials, it’s important to look at the pros and cons of the material’s composition, uses, physical and mechanical properties.
What is glass ionomer cement?
Glass Ionomer ingredients
In general, glass ionomer cements are classified into three main categories: conventional, metal-reinforced, and resin-modified.
These variations mean glass ionomer cement can have a range of compositions, but the chief ingredients of conventional glass ionomer are basic glass and an acidic water-soluble powder that sets by an acid–base reaction between the two components.
It is this composition which gives glass ionomer its unique abilities to release fluoride, a mineral that can reduces cavities and tooth decay, and physically and chemically bond to tooth structure with no need to etch or prime.
Glass ionomer cement can be supplied as powder and liquid (which are hand mixed on a glass slab using a spatula), pre-dosed capsules (for mixing in an amalgamator), or ready-to-use capsules (dispensed directly into the cavity using an injector gun).
One of the more recent glass ionomer advances is a resin-modified GIC that combines traditional GIC ingredients with the addition of light-curing resin to increase strength and wear resistance, thus bringing together the advantages of composite resins and glass ionomers.
Before resin-modified glass ionomer was introduced, metal-reinforced GIC featuring a silver-amalgam alloy power was the hybrid of choice, as it increased the strength of the cement and provided radiopacity.
Glass ionomer uses
Due to its much desirable easy bonding and fluoride-realising qualities, there are several popular uses and indications of glass ionomer cement.
Glass ionomer filling: Glass ionomer cement can be used a restorative material alternative (or complement) to dental composites or amalgam. Two of Kent Express' most popular GIC filling materials are the DEHP Glass Ionomer and Dentsply Chemfil Superior Glass Ionomer.
Depending on its composition, GIC may be used for abrasion and erosion cavities, restoration of deciduous teeth, restoration of class III and class V carious lesions, and tunnel restorations,
GIC is especially favoured in primary dentition as it requires less time to fill the cavity and minimal speed of application. It also has the potential to leech fluoride into the tooth which can prevent secondary caries from occurring under the filling. This is why glass ionomer cement has been especially indicated for Atraumatic Restorative Treatment.
Because non-modified glass ionomer is generally not considered strong enough to withstand masticatory forces due to a tendency to be brittle and wear easier, it is usually used for small restorations in or areas that are not used to bite or chews, for example cervical cavities.
Glass ionomer liner: Modified glass ionomers can be used to line the dentine walls of a deep cavity in a sandwich technique that uses the resin-modified glass ionomer to seal the dentin and provide the benefit of fluoride release. A surface later of resin composite is then used to the fill the remainder of the cavity
Some advocate the use of the glass ionomer as a liner under class I and II composite restorations to relieve stresses that result from shrinkage of the composite during cure.
Fissure sealants: To protect the occlusal surfaces from caries, a glass ionomer coating can be applied to seal the fissures and act as a smooth barrier. This preventative measure is often offered to children and the sealants are applied as soon as the permanent teeth erupt.
Though typically used on emerging molars in children, GIC can also be beneficial for adults as a means of protecting teeth from bacteria and tooth-attacking acids. Though some dentists will prefer composite resins as a sealant, glass ionomer provides major benefit of releasing fluoride which can even repair the early stages of tooth decay.
Luting and bonding: Glass ionomer is commonly used for cementation of crowns, bridges, inlays, onlays and orthodontic appliances. The best glass ionomer luting cements will have high erosion resistance and excellent biocompatibility, such as DEHP Glass Ionomer Luting Cement.
Glass ionomer advantages
- Requires minimal removal of healthy tooth structure
- Decent match to tooth colour, especially in the case of resin-modified glass ionomer cements
- Ease of placement
- Versatility of use
- Bonds exceptionally well to tooth surface without the need for a bonding agent
- Hardens immediately by light curing
- Releases fluoride over time
- Relatively low durability – more prone to fracture and wear than composites
- Lower tensile strength than composites
- Limited shade ranges in comparison to composites
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