Soft acrylic resin materials containing a polymerisable plasticiser II: water absorption characteristics

The main disadvantage of soft acrylic resin denture lining materials is the loss of plasticiser leading to gradual hardening. One possible solution to this problem is the use of a polymerisable plasticiser. A material based on such a plasticiser failed in clinical trials due to a combination of prolonged water uptake and low strength. Similar materials with improved strength have been developed and it is the aim of this study to investigate their water uptake characteristics. Water uptake from distilled water, an artificial saliva and 0.9 M saline has been determined for three experimental materials and 'Supersoft', a commercial plasticised acrylic resin denture lining material. Solubilities were determined after 6 months and diffusion coefficients calculated where appropriate. All the experimental materials had a lower uptake and solubility than 'Supersoft' in all solutions. For each material uptake was lower from solution than from distilled water. All diffusion coefficients were in the range expected for this type of material. The water uptake of the experimental materials was influenced by the relative hydrophilicity of the monomer used.