Biomedical Engineering Reference
In-Depth Information
11
Glass Ionomer Cements:
Application in Pediatric Dentistry
11.1. Introduction
Glass ionomer cements (GICs) are polyalkenoates cements. The
term “glass” refers to the nature of the particles used, based on fluoro-
alumino-silicates, often as a milled fine powder. It can be decomposed
by acid attack and can then release the ions forming the cement,
typically calcium and aluminum ions and, optionally, strontium,
lanthanide or zinc ions, according to the composition. The term
“ionomer” refers to a polymer composed of macromolecular chains,
with a small proportion of ionized or ionizable groups (usually 5-
10%) cross-linked by ionic bridges. This is often polyacrylic acid, but
it may also contain polymers and co-polymers of acrylic, itaconic,
maleic or vinyl phosphoric acid. All GICs are the result of an acid-
base reaction resulting from the mixing of the fluoro-alumino-silicate
glass powder (base) and an aqueous solution of polyacrylic acid
(acid), forming a polysalt which surrounds the glass particles which
have not completely reacted (Figures 11.1 and 11.2).
This composition and structure give GICs unique properties such
as a spontaneous adhesion to dental tissues, a dimensional stability to
moisture, a coefficient of thermal expansion similar to the dental
