Glass ionomer cements

Glass Ionomer Cements

Glass ionomer cements (GICs) are a class of dental restorative materials used in dentistry for filling cavities and as luting cements. They are known for their ability to release fluoride, which can help in the remineralization of tooth structure and prevention of caries.

Composition

Glass ionomer cements are composed of a mixture of fluoroaluminosilicate glass powder and an aqueous solution of polyacrylic acid. The setting reaction involves an acid-base reaction between the glass powder and the polyacid, resulting in a cross-linked gel matrix that binds the glass particles.

Properties

GICs have several advantageous properties:

• Fluoride Release: One of the most significant benefits of GICs is their ability to release fluoride ions over time, which can help in preventing secondary caries.
• Biocompatibility: GICs are generally well-tolerated by the pulp and surrounding tissues.
• Adhesion: They chemically bond to both enamel and dentin, reducing the need for extensive tooth preparation.
• Thermal Expansion: Their coefficient of thermal expansion is similar to that of natural tooth structure, which minimizes stress at the tooth-restoration interface.

Applications

Glass ionomer cements are used in various dental applications, including:

• Restorative Dentistry: For filling cavities, especially in non-load bearing areas.
• Luting Cements: For cementing crowns, bridges, and orthodontic appliances.
• Base or Liner: Under composite restorations to protect the pulp.
• Fissure Sealants: To prevent caries in pits and fissures of teeth.

Advantages and Disadvantages

Advantages

• Fluoride Release: Provides an anti-cariogenic effect.
• Chemical Bonding: Reduces microleakage and enhances retention.
• Biocompatibility: Minimal irritation to the pulp.

Disadvantages

• Mechanical Properties: Lower strength and wear resistance compared to composite resins.
• Aesthetic Limitations: Less aesthetic than composite resins due to opacity and limited color matching.
• Moisture Sensitivity: Sensitive to moisture during the initial setting phase.

History

Glass ionomer cements were first introduced in the 1970s by Wilson and Kent. They were developed as an alternative to silicate cements and zinc phosphate cements, offering improved properties such as fluoride release and chemical adhesion to tooth structure.

Recent Developments

Recent advancements in GICs include the development of resin-modified glass ionomer cements (RMGICs), which incorporate resin components to improve mechanical properties and aesthetics while retaining the benefits of traditional GICs.

Also see

• Dental composite
• Dental amalgam
• Fluoride therapy
• Dental restoration