Biomedical Engineering Reference
In-Depth Information
named resin-modified glass ionomers (RMGICs). From a chemical
perspective, there are two ways to obtain an RMGIC:
-
by adapting the matrix resin to the GIC matrix so that both lead
to an interpenetrating network [ANT 87];
-
by partially modifying the polyacid by grafting it, namely
polymerizable groups (by esterification with HEMA), while the
residual carboxylic groups facilitate the acid-base reaction with the
glass [MIT 91].
The RMGICs activated by photo and chemical polymerization
(Figure 11.3), in addition to the acid-base reaction, have been
described as “dual-cure” or “tri-cure” to indicate a continuing
polymerization under the light source.
Figure 11.3.
The polymerization reaction
High viscous (or condensable) glass ionomer cements (HVGICs)
were also developed. These materials set faster and are of higher
viscosity because of fine glass particles, anhydrous polyacrylic acids
of high molecular weight and a high powder-to-liquid mixing ratio.
The setting reaction is the same as the acid-base reaction of typical
conventional GICs [FRA 97].
