Dental Problems

Glass Ionomer Cement

Glass ionomer material was developed by Wilson et al in the early 1970s. It can be used as a luting cement for indirect restorations, a lining under another restorative material, or a restoration in its own right. Read on know more about the glass ionomer cement.

ToothAdvantages of glass ionomer cement:

  • It is a tooth colored material.
  • It will adhere directly to tooth enamel and the inner dentin tissue through an ion exchange mechanism.
  • It is biologically active, as it is capable of releasing calcium, fluoride and phosphate ions.

Disadvantage of glass ionomer cement:

  • Its physical properties are not sufficient to enable it to withstand heavy occlusal loads in large restorations.

Classification:

The accepted classification is mentioned below:

  • Type I -Luting

    • Cementation of bridges, crowns and orthodontic devices.
    • The approximate ratio of powder and liquid is 1.5:1.
    • Radio -opaque radio
  • Type II -Restorative

    Type II. 1 restorative aesthetic

    • All types of aesthetic restorations
    • Resin modified or auto-cure
    • Powder : liquid ratio 3:1 or greater
    • High physical properties
    • Generally radio opaque

    Type II. 2 restorative

    • Restorations under high occlusal load
    • Resin modified or auto-cure
    • The ratio of powder and liquid is 3:1 or greater
    • Radiopaque
    • Used as a interim restoration or dentin substitute.
  • Type III -Lining or Base
    • Simple lining under a metallic restoration
    • Powder : liquid ratio 1.5:1 only
    • Auto cure
    • Radiopaque
    • High strength base for lamination technique
    • Powder : liquid ratio 3:1 or greater

Constituents:

Powder:

The powder is essentially a calcium fluoroaluminosilicate glass. It is possible to substitute the calcium with strontium and the percentage of fluoride in the formula can also be varied. Phosphate can be added to decrease the melting temperature and modify the setting characteristics. Fine colloidal silver can be added to the mix in an attempt to enhance the properties.

Liquid:

The liquid is essentially a poly alkenoic acid. The usual acid is a 40 -55 percent solution of 2:1 polyacrylic or itaconic acid copolymer of maleic acid and poly acrylic acid. The use of copolymers improves storage. The inclusion of tartaric acid will retain the working time so that the mix will be clinically workable.

The above article discusses briefly about the glass ionomer cement.

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