[Studies on the course of polymerization shrinkage of self-cured and light-cured composites]

The dilatometer method was used to study the linear polymerization shrinkage of five different composite filling materials which, although of similar composition, are available in both the self-curing and the light-curing form. The shrinkage of these materials has been recorded for 5 minutes after setting was initiated. While rapid length changes occurred in the light-cured materials usually within the irradiation period of 20 seconds, the process of polymerization shrinkage lasted longer in the self-cured materials, extending beyond the period of observation. After 5 minutes linear polymerization shrinkage varied between 1.1 and 1.8%.