The effect of an elevated level of residual monomer on the whitening of a denture base and its physical properties.

It has been suggested that incomplete or faulty processing leading to a high level of residual monomer is a factor in denture whitening. Laboratory tests which simulate the cleaning procedures used by patients presenting with whitened dentures have been carried out on specimen strips of acrylic denture base material with high or low levels of residual monomer. The results show that these samples exhibit similar changes and that the high level of residual monomer had no effect on the whitening process, this being attributable to the cleaning method. The major factor responsible for whitening is confirmed as a high water temperature irrespective of the presence of the denture cleaning agent. However, some physical properties were adversely affected by a high residual monomer content (due to the processing method) which has serious consequences for denture-wearing patients. The use of short/low temperature curing cycles now common in many dental laboratories should be avoided.