Glass ionomer cement (GIC) is one of the materials used in the field of dentistry as a filling material. This binding material is also known as dental cement. It also finds application in the luting process. It is commonly used in restoration and repair of teeth, filling cavities, and as a liner in other types of fillings, and was first introduced for dental care in the year 1972. Chemical bonding takes place between dental hard tissues and this material. GIC also releases fluoride which prevents further decay. Preparation and Application Preparation of GIC is achieved through mixture of a powder and a liquid. The material is set due to a acid-base reaction. The materials used in making GIC filling are fluoroaluminosilicate (powder) and polyacrylic acid (liquid). Glass Ionomer Liquid The liquid form of glass ionomer was earlier available in the form of aqueous solutions.The disadvantage of using the aqueous solutions was that they were highly viscous. Over time, these liquids used to gel. Nowadays, this liquid is available in the form of co-polymers. These co-polymers are available with maleic, itaconic, and tricarboxylic acids. These acids decrease the gelation tendency and viscosity of today's glass ionomer liquids, and also increase the reactivity of liquids. Glass Ionomer Powder The powder form is chemically composed of calcium fluoroaluminosilicate glass. The aluminosilicate proportion in powder form is high, and therefore, the reactivity too is greater. The fluoride present in this chemical also is useful, since it plays the role of ceramic flux. Additives like zinc oxide, barium, strontium, and lanthanum are responsible for radiopacity. The raw materials used in the preparation of glass ionomer are heated at a temperature ranging from 1100 °C to 1500 °C. A large cavity in the teeth requires to be filled with some kind of sealant/filling material. Glass ionomers prove to be useful for the purpose of such fillings. If the cavity is big enough (i.e. it reaches below the gum line) this material proves to be especially helpful. These fillings can also be used for the front teeth. Advantages The benefits of using glass ionomer sealants are enlisted below:

• The procedure doesn't require any kind of prior preparation.
• There are less chances of occurrence of problems like tooth decay and leaking. Firm bonding of this filling material with the teeth is the reason why these problems do not occur.
• The filling, apart from binding firmly to the teeth, also helps maintain dental health. This is because fluoride is released by this material over time.
• This material shrinks very less in comparison to other sealants.

Limitations Here are the disadvantages/limitations of using glass ionomer cement.

• GIC does not match the color of the tooth very accurately
• The fillings alternative to glass ionomer such as composite ceramics are much stronger. It undergoes wear and tear quite easily.
• GIC filling doesn't require much preparation. However, the treatment procedure itself is a lengthy one. Each and every layer of this filling has to be bonded separately, and it takes time to fully set and harden; the time required for the whole process is therefore, greater.
• Sensitivity to water can be observed during the setting phase.
• The other limitations like susceptibility to abrasion; brittleness, and solubility make it prone to damage.

GIC is very useful owing to the benefits being offered. However, the limitations of the material should also be taken into consideration.