Development of novel elastomer/methacrylate monomer soft lining materials.

An earlier study identified a formulation comprising a butadiene/styrene copolymer (PBS) gelled with ethyl hexyl methacrylate (5 + formulation) as a potential denture soft lining material. It had good mechanical properties but water uptake was high as a result of the presence of a separating agent. This study has compared the tensile and water absorption properties of four elastomers free from separating agent (three butadiene/styrene, HBS, EBS, SBS, and one isoprene/styrene, SIS) with those of PBS all using the 5 + formulation. HBS is emulsion polymerized; the others are solution polymerized. SIS5 + had the better tensile properties whereas HBS5 + had the lowest water uptake. All the other 5 + formulations had higher uptakes than PBS5 +, which is thought to be due to the presence of hydrophilic groups from the solution polymerization process. All materials showed some sign of oxidation. Emulsion polymerized elastomers are regarded as less suitable for medical uses than the solution polymerized alternatives. Of these, SIS5 + seems to be less prone to oxidation and has the better mechanical properties so was considered to be the most suitable material for further development.