ABSTRACT
The problem of maintenance of water balance led to the development of a resin-modified form of glass-ionomer as an alternative (Mitra 1994). The main difference is the addition of further resins and photo-initiators to the auto cure materials so that they can be light-cured on command immediately after placement in the cavity. The two phases will cross-link, and this apparently has no untoward effect on the normal acid-base auto cure setting reaction, which continues as usual; but it does provide an immediate resistance to early water uptake. There is clinical convenience in this, because the restoration will have a moderately stable water balance
Figure 4.1
Diagram illustrating the water balance of the auto cure Type II.1 restorative aesthetic glass-ionomers. Note that water uptake is a serious problem in the early stages following placement. Water will penetrate through the entire depth of the restoration very rapidly and downgrade both physical properties and, more importantly, translucency. It is also important to be aware of the potential for water loss for up to 6 months after placement.
