dental02.jpg (11342 bytes)Fundamentals of
Dental Materials

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Restorative Materials

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1-17. CHARACTERISTICS OF GLASS IONOMER CEMENT

a. General. The primary use of glass ionomer cement is for permanent cementing of inlays, crowns, bridges, and/or orthodontic band/brackets. In addition, it can be used as a cavity liner and as a base.

b. Clinical Uses. Glass ionomer cement is used in the same way as zinc phosphate cement, both as an intermediate base and as a cementing medium.

c. Chemical Composition.

(1) Powder. The composition of glass ionomer cement powder may vary slightly depending on the manufacturer. It generally contains a mixture of aluminosilicate glass with dry polymaleic acid.

(2) Liquid. Glass ionomer cement liquid consists of an aqueous solution containing an accelerator. (A chemical accelerator shortens the setting time.)

d. Properties. Glass ionomer cement is free from phosphoric acid and has very low solubility. It adheres chemically to enamel and dentin and, readily, to wet tooth structure, leaving minimal film thickness. It is well tolerated by the pulp and remains rigid under a load, exhibiting no creep. Glass ionomer possesses high compressive strength. It releases fluoride ions to tooth structure. It is simple to proportion, mix, apply, and clean up.

e. Setting Reactions. For glass ionomer cement as for other dental cements, the working time is reduced if a higher powder to liquid ratio has been used. Higher temperature shortens working time and lower temperature extends working time. Glass ionomer cement should always have a glossy appearance. When the surface becomes dull, the setting reaction has started, and the mix should be discarded. Exceeding the working time will result in loss of adhesion to enamel and dentin.

David L. Heiserman, Editor

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Revised: May 22, 2017