e. Precautions. The following precautions should be observed.
The interior of restorations and tooth surfaces must be free of saliva.
The mix should be used while it is still glossy, before the onset of
(3) The powder and liquid should be stored in stoppered containers under
cool conditions. Loss of moisture from the liquid will lead to thickening.
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.
(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.