Glass Ionomer

 It is a Dental restorative material used as Filling material, Luting agent (including orthodontic brackets). GIC is based on the reaction of silicate glass powder (calciumaluminofluorosilicate glass) and polyacrylic acid. This reaction produces a powdered cement of glass particles surrounded by matrix of fluoride elements, chemically called (glass polyalkeonate).

GIC is primarily used in the prevention of dental caries. It has good adhesive bond properties to the tooth structure, as it forms a tight seal between the tooth and the environment. GIC acts as a sealant when pits and fissures in the tooth occur and release fluoride to prevent further enamel demineralization and promote re-mineralization. Fluoride hinders bacterial growth by inhibiting their metabolism of ingested sugars in the diet. It is recommended that the use of Fluoride varnish alongside glass ionomer sealants in practice further reduces the risk of secondary dental caries.

Clinical uses:

1. Cermets: Metal reinforced glass ionomer cement.

The development of cermets is an attempt to improve the mechanical properties of GIC, i.e. Brittleness, abrasion resistance by incorporating metals such as silver, tin, gold, titanium.

2. Dentine surface treatment:

GIC has adhesive properties, useful when placed in undercut cavities. The cavities should be adequately prepared before placement of the cement by removing the precipitated salivary proteins, the most effective way is by applying the GIC liquid i.e. Polyacrylic acid. It is applied for 30 seconds and washed off.

3. Fissure sealants:

Involves the use of glass ionomers with fluid consistency that allows the cement to flow into the pits and fissures of posterior teeth.

4. Orthodontic brackets:

Involves the use of glass ionomers as an adhesive cement which forms strong chemical bonds between enamel and many metals such as stainless steel.

5. To restore Cervical abrasions on the buccal surfaces of the teeth, which may occur due to wrong brushing techniques etc.

Handling: Starter materials of glass ionomers are supplied either as

1. powder and liquid or
2. powder mixed with water or
3. mixed form can be provided in an encapsulated form. A paper pad and a plastic spatula should be used for mixing the cement and to derive the desired consistency.

This chemical reaction involves 4 overlapping stages: Dissolution, Gelation, Hardening, Maturation. Important to note that glass ionomers have longer setting times and need protection from the oral environment to prevent dissolution and contamination.

RMGI: Resin modified glass ionomer cement. The addition of resin to the glass ionomer improves the handling properties significantly, i.e. Mixing and placing. They allow equal or higher amounts of fluoride release and there is evidence of higher retention, higher strength, and lower solubility. Resin modified glass ionomers have two setting reactions,

1. Acid-Base setting,
2. Free radical polymerization.

Only the material properly cured by light will be optimally cured. Due to the shorter working time, it is recommended that placement and shaping of the material occur as soon as possible after mixing.

Thank you For Reading this, Do reach us in case you have any queries or have any doubts

By Dr. Abhilash dandy

Qualification: B.D.S

I graduated as a Dentist from Sibar Institute of Dental Sciences, Guntur. I have done my externship program at Rutgers school of dental medicine, New Jersey, USA. I have a clinical experience of 3 years and currently working as Administrative head — Dental wing in MediCub India, Hyderabad.