Glass Ionomer Filling Cement
A glass ionomer cement is a dental restorative material used in dentistry for dental fillings and luting cements. These materials are based on the reaction of silicate glass powder and polyalkenoic acid, an ionomer.
Glass Ionomer Cement
Main article: Glass ionomer cement
The concept of using “smart” materials in dentistry has attracted a lot of attention in recent years. Conventional glass-ionomer (GI) cements have a large number of applications in dentistry. They are biocompatible with the dental pulp to some extent. Clinically, this material was initially used as a biomaterial to replace the lost osseous tissues in the human body.
These fillings are a mixture of glass and an organic acid. Although they are tooth-colored, glass ionomers vary in translucency. Although glass ionomers can be used to achieve an aesthetic result, their aesthetic potential does not measure up to that provided by composite resins.
The cavity preparation of a glass ionomer filling is the same as a composite resin. However, one of the advantages of GI compared to other restorative materials is that they can be placed in cavities without any need for bonding agents (4).
Conventional glass ionomers are chemically set via an acid-base reaction. Upon mixing of the material components, there is no light cure needed to harden the material once placed in the cavity preparation. After the initial set, glass ionomers still need time to fully set and harden.
Advantages:
1. Glass ionomer can be placed in cavities without any need for bonding agents .
2. They are not subject to shrinkage and microleakage, as the bonding mechanism is an acid-base reaction and not a polymerization reaction.(GICs do not undergo great dimensional changes in a moist environment in response to heat or cold and it appears heating results only in water movement within the structure of the material. These exhibit shrinkage in a dry environment at temperature higher than 50C, which is similar to the behavior of dentin.
3. Glass ionomers contain and release fluoride, which is important to preventing carious lesions. Furthermore, as glass ionomers release their fluoride, they can be "recharged" by the use of fluoride-containing toothpaste. Hence, they can be used as a treatment modality for patients who are at high risk for caries. Newer formulations of glass ionomers that contain light-cured resins can achieve a greater aesthetic result, but do not release fluoride as well as conventional glass ionomers.
Disadvantages:
The most important disadvantage is lack of adequate strength and toughness. In an attempt to improve the mechanical properties of the conventional GI, resin-modified ionomers have been marketed. GICs are usually weak after setting and are not stable in water; however, they become stronger with the progression of reactions and become more resistant to moisture. New generations: The aim is tissue regeneration and use of biomaterial in the form of a powder or solution is to induce local tissue repair. These bioactive materials release chemical agents in the form of dissolved ions or growth factors such as bone morphogenic protein, which stimulates activate cells.
Glass ionomers are about as expensive as composite resin. The fillings do not wear as well as composite resin fillings. Still, they are generally considered good materials to use for root caries and for sealants.
Resin modified Glass-Ionomer Cement (RMGIC)[edit]
A combination of glass-ionomer and composite resin, these fillings are a mixture of glass, an organic acid, and resin polymer that harden when light cured (the light activates a catalyst in the cement that causes it to cure in seconds). The cost is similar to composite resin. It holds up better than glass ionomer, but not as well as composite resin, and is not recommended for biting surfaces of adult teeth.
Generally, resin modified glass-ionomer cements can achieve a better aesthetic result than conventional glass ionomers, but not as good as pure composites. It has its own setting reaction.
