[Photopolymer shrinkage and its interaction with cavity liners]

Comparative in vitro trials concerning the problem of cavity liners detaching from the floor of the cavity when combined with photopolimerizable filling material demonstrated that gap formation occurred only if slowly setting glass ionomer cement was used. No such effect was seen with fast setting glass ionomer cement or phosphate cement. Gap formation is due to the curing process of slowly setting glass ionomer cement.